texts: Braking a small hall sensor BLDC motor on a ballscrew

texts:
I want to create a simple circuit (or better, add software change for the existing circuit) for deceleration of a small BLDC motor connected to a ball screw. Exact stopping at zero is not a requirement.

Motor is 48V, max 3000rpm, rated 220W. Ball screw is 1605 type, 400mm long, no gearbox so max linear speed 0.25m/s, mass attached approx 3kg - so not a huge amount of momentum. Power is from a 300W SMPS PSU.

The current motor design is by 3 phase commutation with PWM on the high side and continuous on the low side with the PWM approximating a sine wave based on the last rotation period adjusted by a lookup table to be based on empirical measurement of acceleration and current speed. It is a fairly trivial setup on a homemade controller.

What I want to achieve is braking at an inverse to the motor's acceleration (so that the motor's velocity approximates a sine wave)

Options:

1) Freewheeling: If I cut the power I expect that while it will slow, it would be at a lower rate then desired.

2) Regenerative braking: Not an option. I do not need or want this complexity in the circuit as it would require adding a large store.

3) Dynamic braking: A possibility, but it would require adding a large resistor and the associated circuitry, I would like to avoid if possible.

4) Reverse the engines Mr Scott!!!: If I understand the term correctly this is known as "plugging". In practical terms that is to set the MOSFET states based on the hall sensor lookup as if the motor were rotating in the opposite direction. As is probably obvious this is the solution I would like to go for - but I have a collection of known unknowns and expect there are unknown (to me) unknowns.

So known unknowns:

a) This causes stress on the electrical components - how much and how to limit it?... Specifically is the PSU or anything else on the board going to be exposed to over voltage or excess current?

b) This causes stress on the mechanical components. I assume this is in therms of rapid declaration on all parts and waste heat in the motor and probably the ball nut.

Is it possible by using a lower duty cycle on the high side PWM while in this state to moderate the excess voltage/current/heat effects? If so at what maximum levels compared to normal? 10%? 50%? or inversely proportional to the speed?

5) Lastly am I missing something else obvious that would achieve the desired result but in a simpler way?

Constraints:

i) Extra hardware is possible but "expensive"

ii) Changes to software control of the PWM states for any of the 6 MOSFETs is trivial.

iii) Changing to an off the shelf control is not an option I wish to consider.

iv) Please describe answers in terms of MOSFET states A, B, C high and low. (Ah, Al, Bh, Bl, Ch, Cl) or by providing circuit diagram where suggesting relevant changes.

Thanks


texts: Rated vs. actual power usage of a linear fluorescent lamp

texts:
After having some power issues, I've decided to investigate the largest power drains in our company, and I've arrived at a realization that 128 lights adds up to a lot of power (and that's not even all of them!).

Overall, I'm looking at the feisability of replacing all lamps with LEDs, but I'd like to avoid surprises of actual power usage being significantly higher than rated. As I started calculating the power usage, I've realized that there is a fairly large difference between the actual power draw and rated power.

The measured current at the grid connection was 0.31667 A / lamp - lowest result was used as "currently most efficient", though there might have been a busted lamp among them. Measurements were made in different areas for reliability and I made sure all other power users were accounted for. In this case, all lamps are linear fluorescent lamps, T8 58W 150cm, using starters.

Using the "standard" 220 V, I get the following result:

  0.31667 A * 220 V = 69.6674 W

Using the calculated 233.33 V from the 35 kW, 3 x 50 A grid connection, I get this instead:

  0.31667 A * 233.33 V = 73.8886 W

However, both are a far cry from the lamps' rated 58 W

  0.31667 A * 183.1560 V = 58 W

Am I calculating something wrong? Is the discrepancy due to lamp deterioration or starters? Is there something else obvious that I'm missing?

Is this discrepancy also something I should worry with the planned LED replacements? Considering current lamps are 58 W and LED replacements would be 24 W.

I'm no expert and although I'm well aware that A * V = W isn't how it always works, I presumed that it should be accurate enough for lamps.


texts: How does one use more than one device requiring the same input voltage on one/same power supply?

texts:
Lets say I want to power a high output LED powered by the appropriate/included driver as well as a heatsink fan; they both expect a 12V input voltage, but the LED driver expects 900mA meanwhile the fan expects 90mA.  The desired power supply would be AA batteries.

What would I need to add to my circuit to work under the same power source, how would I wire it, would I still power it off of 12 volts (therefore 8xAA batteries)?


texts:
I am calculating the transfer function of a system. I reached a deadlock:

$$L\{f(t)\cos(\theta t)\}$$

Laplace transform of the product of any function by cosine. For a few days I have been searching for a way to solve this, unfortunately without success. Could anyone help me?


texts: 555 and output amplifer with different Vcc supplies

texts:
I want to increase the power of the push-pull amplifier in this circuit. The left 555 generates a square wave and the righthand 555 is triggered by it, and the output of both is amplified by the pairs of transistors. (image below).

While the 555 has a maximum Vcc of 18 volts, the maximum Collector-base voltage and Collector-emitter voltage is 80 volts for both the NPN and PNP Darlington power transistors.

Question: Can I increase the supply voltage to the amplifier transistors to 30 volts in order to increase the audio output while keeping the 555s at +12 volts so I don't fry (highly technical term) them? (image below.)

So:

1) Do I need a capacitor between pin 3 (the 555 Output) and the base of the NPN/PNP pair? Or use some other method of isolating the 555 output from the amplifier input? If so, do I need a capacitor or something else between the output of the left 555 and the input of the right 555?

2) How to I calculate the resulting wattage on the speaker? The speaker is a piezo tweeter, rated 200 watts, and the manufacturer suggests a 30 ohm resister in series to "prevent amplifier burnout." With an ohmmeter, the speakers show no resistance when out of the circuit, so they are not traditional 4 or 8 ohm speakers.


texts: What multi/many-core (micro)processors/controllers should I use for "embarrassingly parallel" computations?

texts:
This is my first question ever on this site, so I hope I don't mess this up. :D

I'll try to be as specific as possible.

What I need:

Something that I can program in C (or a C-like language).
I need a processing unit that can be connected in an array for massively parallel computations.
The unit should have a many/multi-core architecture (32-bit RISC is good enough) and the cores as well as the units should be able to communicate with each other.
All units should be simultaneously programmable. I don't want to program every one of them by hand.
Every core will run the same simple algorithm, but with a different nonce.
Cores times speed divided by price should be as high as possible.
The resulting array should be able to outperform a standard desktop computer by several orders of magnitude regarding highly parallel computations.
The solution shouldn't be too complicated.
I don't really care for power efficiency. As long as it doesn't require ridiculous amounts of power (such as a private nuclear power plant per cpu) it shouldn't be a problem.

What I need it for:

Neural Networks & various other implementations of Machine Learning
Finding prime numbers, as well as other math-related problems (such as Collatz conjecture, etc.)
Hashing & other brute-force applications
Among other parallel programs.

What I've found so far:

GPU accelerated computing:
This solution seems to be the best I've found so far. Using CUDA & OpenCL I can use the hardware shaders of a GPU as individual cores. This is how Bitcoin mining was done in the past.
The upside of this approach is that I can have hundreds of threads running simultaneously. Also there is a lot of online support using this method.
The downside of this approach is that GPU shaders are terrible at conditional branches, thus hindering me of writing any such programs with many nested conditions.
XMOS chips
One of the first family ICs I've stumbled upon that seemed appropriate was the xCORE product range. They are microprocessors that are relatively cheap (~20USD each) and can have up to 32 cores.
What is a bit off-putting is the fact that the only indication of speed is in MIPS. Looking at a hookup guide, they use a 25MHz external crystal. Also there isn't too much online support.
The Parallella Board
This is a very interesting little board that is marketed as a "credit card sized supercomputer". It runs a derivative of Ubuntu and has a Epiphany-III co-processor with 16 cores (I think). They say it can execute 90 GFLOPS.
The downside is that I need more cores.
Epiphany-IV (E64G401)
This microprocessor seems perfect. It is made by the same company as the Parallella board and features 64 RISC cores at a whopping 800Mhz.
The only downside is that this IC is discontinued. :'(
Kalray processors and PCIe cards
Again a very interesting solution for parallel computation, where the processors have up to 256 cores. Kalray also offers training in using their products.
The downside is that one has to request for a price and it seems like one can only buy these components from them directly. Also it seems to me that they are more focused on networking.
FPGAs
FPGAs have also come into consideration, as they can perform entire algorithms in single clock cycles.
What I'm looking for though is something that can also perform very large algorithms, while FPGAs don't have that many logical elements.

Budgetwise I'm really flexible. So let's say 10'000USD.
I'd prefer to design my own computing array pcb with an ic you guys recommend, however I'm open to other solutions. Maybe I've already found the best solution but I don't know it yet. What do you ladies and gentlemen think?

Thank you very much in advance!

-- Linus

Changelog:

Added that I'd like to program in C
Added FPGAs
Added that I don't care for power consumption
Added that I'd prefer to make my own pcb
Added budget of 10 000 usd


texts:
I'm working on passion project that would allow me to control laser and mirror galvanometer (galvo in further text) using Arduino board.

Laser and galvo that I've bought are encased in plastic housing unit and galvo can direct laser beam only horizontally, it was spare part from laser printer and came without any wires.

Photo album of galvo in question:
https://photos.app.goo.gl/yYuCsytvfRXX8Vnv8

Since I don’t have experience with electronics I need help figuring some things out.

What kind of wires (input jacks) do I need to buy for laser and galvo circuit boards (designated in the images above)?
What kind of power supply do I need?
What kind of Arduino board do I need?
Any additional equipment?

It should be taken into consideration that I plan to add camera so I can manipulate laser through optics instead sight, after I finish this first part of the project.

Thank you.


texts: What is the purpose of external terminals on a logic probe?

texts:
I have an LP-3500 logic probe. In addition to the normal connectors to power and ground at the bottom, it comes with two external terminals (one red, one black), which can be connected on the side near the tip:

What is the purpose of the external terminals, and how are they used?


texts: I once found out that basis of this circuit looks like a Royer oscillator. What makes this circuit oscillate?  Especially, it is still not clear in my mind that what is the function of capacitors and the diodes at the bases of the NPN transistors. Is there a way to tune the passive elements in the base drive?


texts: How to measure the delay of one single inverter in ASIC?

texts: In practice, is it feasible for a chip manufacture to reliably and accurately measure the delay of one single inverter in ASIC? If it is, how can one go about doing it?


texts: I want to make a compact, high volume fan, in an enclosed box. Weight, noise, and air volume are important. Can I power a 12V 1.0A; Speed: 3000RPM; Air flow: 38.5CFM; Noise:45dBA fan with a 12V and 2 AA batteries?


texts: Burned cable while trying UPS transformer with no load

texts:
I have this big transformer taken from an old UPS. I wanted to use it to build a linear high current 12V power supply, so I was testing if it was suitable for the task. Unfortunately it has no ratings, but I assume it would be capable of delivering at least 10A.
Here are a couple of pictures of the transformer: https://imgur.com/a/PEsIrfS
These are the resistance of the windings:

grey-violet 1.61 ohm
brown-blue 5.22 ohm
black-red(right) 0.15 ohm
white-red(left) 0.15 ohm

I connected brown-blue to the mains (230V) using a regular PC cable (rated 2.5A 250V) and took some measurements. In this configuration, both black and white with the respective reds were 13,8VAC, but grey-violet was out of range with my multimeter (UT61E).
Then I tried to connect grey-violet to the mains, and this is where the PC cable immediately burned.
My question is, why there was this big current absorption if there was no load connected (just my multimeter)? And why only when I connected grey and violet? Is this transformer still safe to use, provided that the resistance measurements remained the same and its cable show no signs of burning (maybe the 2.5A cable acted as a fuse)?


texts: I've designed the following circuit for a battery charger. With the PIC just turning the output on and off when it is charged. For the program design what would be better, to have the analogue input constantly checked? Or to have the output on for the charge time then to move to the second?


texts: Would this be a legal VHDL architecture?

texts:
I want to design a basic BCD to XS3 converter using VHDL. I am fairly new to
conditional and behavioral architecture implementation, but I was wondering if this would be a legal program, especially my assign statements

entity bcd2xs3 is
    port (bcd : in std_logic_vector(3 downto 0);
          xs3 : out std_logic_vector(3 downto 0));
end bcd2xs3;

architecture behav of bcd2xs3 is
    begin
    case bcd is
        when X"0"|X"1"|X"2"|X"3"|X"4"|X"5"|X"6"|X"7"|X"8"|X"9" => xs3 <= std_logic_vector(unsigned(integer(unsigned(bcd))+3));
        when others => xs3 <= X"0";
    end case;
end behav;


texts:
How does one use a standard PHYS Ethernet controller? The datasheets do not give any schematics and mainly just give the pin descriptions.

I would like to serialize a TDM data stream, or a bit stream, through the Ethernet control to benefit from all of it's transmission methods rather than have to create these methods myself.

Since I want to stream the data as fast as possible I do not want to use packets.  From the datasheets of a few PHYS Ethernet transceivers from TI they connect the inputs of the controller from a MAC and say use the term MII.

The best I can tell is that MII is a very minimum packet wrapper of the data. Does this mean I can't simply stream bits to the Ethernet control but must package them first?

Also, since I am bit dumping the data rather than using packets I need to tell the receiver in some way where the frame of data starts(it is repetitive) so it knows where "bit 0" is. I was going to use a separate TP for this but this seems like quite a waste. I think I use the 8b/10b to signal the first packet using one of the control words or something similar? But this assumes I can actually program this to the Ethernet controller?

This would be rather easy to do in FPGA as far as I can tell(I don't have a lot of experience with it though)? Would it be better to use an FPGA to encode the bit stream into 8b/10b and use control words to signal the start of the stream and still be able to get high speeds data transmission? (obviously still use differential signaling and magnetics like ethernet/RJ-45)

An FPGA would be suited ideally as a front end for my application and I imagine one could easily implement an ethernet controller on an FPGA. I do not want to implement a full controller though but simply use the FPGA to send data down TP or even FO. What are the draw backs to using an FPGA in this case to "emulate" an ethernet controller ignoring the "programming" issues(I assume one can probably download them)?


texts:
I have built a DTMF decoder which offers relay closures corresponding to the digits received. Everything works great, except the equipment I am interfacing to is slow.

The office telephone system gives a pulse of tone whenever a digit on the telephone is held down. From what I've read, the pulse lasts 300ms. The equipment my DTMF decoder is interfacing to cannot detect a pulse that quick.

I am working on getting the tone pulses extended to 1s, but need a plan B. Can anyone think of a way to take a 300ms pulse and extend it to 1s?

I've tried using a 74LS123 (retriggerable multivibrator) but I dont think the IC is designed to go that long.

I've thought of using a JK Flip Flop to latch in the signal that eventually closes the relay contacts, but haven't worked it out yet. I have a limit on the amount of real estate I can use.

I'm looking at some kind of RC charge/discharge circuit to hold the relays on. But I cant figure out a way to have the capacitor charge in 300ms and discharge over 750ms - 1second.

Any input would be appreciated.

Very simplified schematic attached.


texts: Connecting two electromagnets against each other to study self-inductance

texts:
In one article explaining the self conductance a figure like this was used: I added the field lines by myself, what I have noticed in it is the way the two electromagnets are connected by, and I asked myself why they are not connected like this:I mean to make the wire coming from the left electromagnet pass behind the core of the right electromagnet, and then the field direction would change. I, to some extent, understand self-inductance, and I wonder if connecting them as in figure 1 is only the right thing to have an induced emf, could you please help me understand the self inductance in this case, and to tell me whether the two connections are right?
Notes: Neon lamp in the circuit is put to prove that a high induced emf will be produced, because that lamp needs 180V, and the battery is only 6V, so the Neon lamp would glow when there is an induced emf.


texts: 24VAC LED flood with 12VAC driver works on 12VDC—how?

texts:
I bought some cheap RGB flood lights from aliexpress.com. They were supposed to be DC24V (I intend to run them off a solar/battery setup) but I ended up with AC24V instead. What clued me in was the brown/blue connecting wires, when I was expecting red/black for DC.

Opening the thing up though, I find this:

An AC12V LED driver! And, curiouser and curiouser, when I hooked it up to a DC12V power supply it lit! I could only get red light and the IR remote control didn't work, but the magic smoke didn't leak out.

What is going on?

Why does something sold as an AC24V device contain an AC12V driver?
Why did applying a DC voltage to an AC device not blow it up?
Why could I only get red out of the LED and not any other colours, and why did the IR/control circuitry seem to not work?


texts: Load curve control via differential pair

texts:
Last few weeks I have been designing a circuit, which is inputted with saw wave and outputs (amplification fairly linearly if possible) amplified voltage across two loads, where load voltage/current signals are symmetric but inverted - this is done via differential pair.
This is fairly simple, but what is not is gaining control over the setting of meeting point - the point at which two load curves intercept (have equal value of voltage/current at that time) while having range of output load voltage unaltered (that is 0 to \$V_{peak}\$). The current setup of adjusting meeting point is kind of unpractical, since multiple parameters need modification.
As conclusion I could say that I'm trying to achieve adjustment of one of circuit's parameters in order to modify load curve meeting point while load voltage swings from 0 to \$V_{peak}\$ (whereas \$ V_{peak} \$ value stays constant for all possible settings of meeting point).

Here are some of my side notes to this design (as extra):

Modifying meeting point means changing voltage level at which two load curves meet, as one increases and other decreases. In achieving such task I have been trying to somewhat adjust \$V_{bias}\$ and \$V_{src}\$ (in some cases also adjusting \$R_2\$ slightly in order to achieve symmetrical peak values).
As it can be seen from my notes, I tried coupled and uncoupled approach of input source. In both cases \$V_{bias}\$ and \$V_{src}\$ need modification in order to alter meeting point of load curves, but also \$V_{peak}\$ changes with each modification.
Here is what I refer to meeting point modification (from left to right; decreasing meeting point):

Should I either try a different approach (not with differential pair), add some kind of additional circuit to this one or is such circuit sufficient for stated requirements but should meeting point be adjusted somehow differently?
*P.S.: I'm almost certain that coupled design might not be best idea, since input capacitor should be very high, which makes \$ \tau=R_{input}*C_{coupling} \$ high and that is a problem since in takes a lot of time for output load curves to become symmetrical (due to \$ C_{coupling} \$ slowly charging and bias of \$ Q_1 \$ slowly approaching desired bias voltage, where both collector DC voltages of differential pair are the same).
Also, this circuit is meant to be operating at VLF (output saw wave period not less than 1 \$ s \$).
\$ EDIT: \$ As mentioned in the comment section, my real intention is to vary slope of modified saw signal while maintaining signal's frequency - analogy of such signal somewhat similar to PWM, where one controls OFF and ON time of square wave. Imagine this signal similar to PWM, instead of progressively shortening ON time, one could shorten part of period, where signal's amplitude is increasing but so would increase the signal's slope in order to maintain signal's frequency. The idea is visualized in a time graph above (observe only one curve of three different situations and you can see, how period of signal remains unchanged when OFF time is "implemented" but slope of the period, where signal's amplitude increases, also increases).
Here is how I imagined this signal to be generated, as OFF time would be increased:

Such circuit would then be a part of a system, where saw wave at the input is generated with microcontroller via DAC and modified signal of saw wave is driving the load. Also there is an option of controlling certain parameters of a signal conditioning circuit (the one that is shown above) like amplitude swing of input saw wave and its offset, plus tail current of differential pair with bias voltage of \$ Q_5 \$.


texts: Let's say I placed a peltier on the stove, at what temperature will the device fail? Would a temporary failure happen, if so what temperature and is there a permanent failure temperature, whereas the device is permanently destroyed.


texts: Which winding is the auxillary winding in a permanent split capacitor motor?

texts:
I have an induction motor, I'm very sure its a permanent split capacitor motor. One winding is 16 ohms, the other is 4 ohms. I have seen that the higher resistance winding, the 16 ohm one, is the auxillary winding connected through the capacitor, but someone also told me otherwise. How should I connect it?

This is an expansion of Unknown induction motor wiring?


texts: Connfly 50-mil IDC mating part (types of socket/connector pairs)

texts: I am unable to find the right mating part (connector) for this 50-mil contact pitch (supposedly) IDC socket. The groove in this particular socket has an offset, and I am unable to find any connector that fits this. The connfly website is rather unhelpful in this regard, as I am not even able to find this socket in their product list, let alone a mating part. It would be great if somebody could point me in the right direction, or has used similar sockets before.


texts:
I recently purchased this item to use with an arduino:

http://www.sparkfun.com/commerce/product_info.php?products_id=9105

My problem is that I realized after the fact that this wasn't attached to the breakout board. Are these connections too small to be soldered by hand? What is the smallest distance between connections that can realistically be soldered by hand?


texts: Custom photodiode symbol in LTSpice 'syntax error in transmission line statement: ".."'

texts:
I want to simulate different opamps for use in the transimpedance amplification stage in a position sensing device (PSD) photodiode.

The equivalent circuit for the PSD photodiode is saved in psd.asc.

The transimpedance amplification schematic is saved in opamp.asc.

From the standard library I copied diode.asy and added the two light arrows. Furthermore I adjusted the input and output labels and changed the prefix, name letter from D to P.

I was able to select psd as a component in opamp.asc. However when I want to run some transient analysis I get the error message:

  Syntax error in coupled transmission line statement: "p1 n0001 0 pd"

I configured the current source in psd.asc to emulate a triangle current response if it matters.

The corresponding LTSpice files are available as Gist.


texts: Finding the touching angle on a touch-screen?

texts:
I am wondering if it is possible to detect from which direction (or at which angle) a human touches a touchscreen.

Imagine something like this:

Is there any technology out there (e.g. special capacitors) that can determine the angle resulting from touch B (approx. 45 degrees) and that resulting from touch A (approx. 135 degrees)?

I think I am missing the correct keywords to research this.


texts: Working of INA826 instrumentation amplifier for Pt100 RTD

texts:
The schematic below contains an INA826 used to amplify the resistance of the Pt100 RTD across J1.  Gain is set to 10 through the 5.49K ohm resistor.

Is this ciruit amplifying only the voltage across the RTD or are any other voltages involved?
Why not connect -IN to GND, and +IN to a junction of a 5V voltage divider consisting of known resistance and the RTD?
What is the advantage of the present schematic over the one mentioned above?


texts: Can anyone tell me why can the author just write the formula of Thevenin equivalent voltage of this circuit?

texts:
How to find the thevenin equivalent resistance and voltage?

simulate this circuit – Schematic created using CircuitLab

The solution for calculating the thevenin resistance is

\$(5//20)+2+1+2=9\$,i can understand this methodm,just let the current source become open circuit,and let the voltage source become short circuit

However,i can't understand the solution for calculating the thevenin voltage

\$V_{th}=5 \times 2 +25-25\times \frac{20}{20+5}=15V\$

Can anyone tell me why can the author just write the \$V_{th}\$ formula above?


texts: wiring a 3 position toggle switch for two devices?

texts:
I am building a plastic vacuum molding device that requires a heating source and a vacuuming source.  For safety reasons I want to install an On/Off/On toggle switch so I, or whomever, am forced to have either the heating element on OR the vacuum source on...and in the middle position both devices are Off.  In this mode...after the heated plastic is ready for molding, I must switch on the vacuum...and by doing so I am automatically turn over the heating element. (I have read too many times where people leave their heating source on and forget about it...I want to eliminate this hazard).

Both heating element and vacuum each use a standard 110 plug and each is connected to a separate single standard 3 pronged home wall-outlet.  The wall-outlet is not the 2-in-1 type outlet you find in homes, mine are separate, single plug outlets - one each.

My 3-position toggle switch has 6 connectors at the base.  And lastly, I am using a 6ft extension cord that will connect to the 3-position toggle switch on one end and into the a wall-outlet on the other end.  The exposed wires on the toggle-switch end of the extension cord are black/white/green.  I also have 3 feet of 16 gauge copper stranded wire (3ft of black/white/green each) to connect between the two outlets and the toggle-switch.

A.  How do I wire each single port/plug outlet to the toggle switch to achieve the desired outcome?
B.  How do I wire the exposed end of the extension cord to the toggle switch?

Toggle Switch Diagram:

Designation:      Heat     OFF     Vacuum
TOP 3 Toggle:       ON     OFF     ON
Bottom 6 Pins:       o      o      o
                     o      o      o

Here is a link to the toggle switch I am using:  Home Depot Toggle Swtich

Here is the link to the crude image of what I need to accomplish. Crude Drawing

Could you please fill in the blanks of which wire connects to which toggle switch pins?

Thanks in advance.


texts: How do I solder that? The solder won't stick

texts: I have those four holes and I need to somehow make a good connection with them and the Arduino. I'm using a jumper wire and I'm trying to solder it but the solder won't stick. I don't know what to do. Is it possible to do with household items (because coronavirus doesn't allow me to go out and shops are probably closed)? I don't have a solder paste.


texts: A friend of mine came up with an idea for something dealing with a micro-processor running C natively.  Problem is, we need to be able to know if there is a processor out there already before we spend our time and money on something.  Does anybody have any clue about such a processor?


texts: USB single chip ESD protector for two connectors through a power switch

texts:
How to connect USB protector against Vdd line with a single chip ESD protector?

I have a USB power switch for VBUS (MAX1564ETE+) and I plan to use DALC208SC6 for both USB connectors. I connected temporarily V+ of protector to main 5V (which is before USB MAX1564 power switch) but I am not sure this is right.

More appropriate in my case seems to keep V+ of DALC208SC6 connected to a zener, but what value?

Thanks for advices.


texts:
I am designing a board for my project which is powered from 4.2V Li-Ion Battery. I am using a buck-boost converter ADP2504 for powering the board which outputs 4.0V constant voltage. I have buzzer on my board for alarm applications. Whenever I turn on my buzzer I get a huge drop of 1.4V in my regulator output (attached is my drop waveform) and comes back to 4.0V in 33 microseconds.

When I turn on buzzer, current shoots up by 200mA (buzzer current = 200mA). Question is

How to calculate a capacitor to handle this transient with the above input? Currently I don't have any capacitor in my board. Above observations are without capacitor.

If the calculated value is very high in 100's of micro Farads, how to handle inrush current caused by that?


texts: ISP programming W25Q32 SPI flash memory chip

texts:
I have Sofi SP8 programmer for serial flash memory, with ISP interface for In-System programming.
I want try it to read/write memory chip WINBOND 25Q32BVSIG-1246 on board, without desoldering.
Manual have notes about this, but it's not clear a few points: if use programmer to provide power supply for the chip (device is power off), how to connect WP and HOLD pins to VCC? ISP interface have VCC pin(#2) that need be connected to VCC pin of chip, so, additionally WP & HOLD pins on chip must be connected to ISP VCC pin too? Should I use some 1 to 3-pins male header adapter for this to split programmer VCC pin to 3 pins?

The other method is to use Power supply from target board (so device should be power on).
Which way is preferable?

Here is ISP programming description from programmer Manual.


texts:
I came across this image, showing an apparently working motherboard soaked in cooking oil, using the heat from the electronics to deep fry potatoes.

Like most of the internet, the content is of course not trustable. That is why I am asking this question to see if such a thing is at all possible.

I found this question regarding the temperature at which electronics can work, whose answers hint at a maximum of 70C. That doesn't seem true about computers though, as the CPU at least may get even up to 85C and working.

In the image, there is also a thermometer that shows 115, but I can't make out the unit.

So, first of all, can electronics be drenched in oil and still work? If so, is it possible for them to be drowned in oil (which absorbs the heat from the electronics) heated up to such a high degree?


texts: What is the ac collector resistance for the transistor Q1? I am having trouble finding which resistors are in parallel with each other in the circuit above. I want to find the voltage gain and power gain for the circuit in terms of beta,i.e beta parameter of transistor


texts: Does audio OP-AMP circuit needs output capacitors?

texts:
I saw schematics with and without output capacitors. So in the end - do you really need capacitors in the output?

I am using OPA2134 operational amplifier.  I plan to use it both as headphone and line amplifier.

Schematics without output capacitors:

*

*


texts: ST-Link cannot software reset my STM32 MCUs over SWD

texts:
I've been working on a problem with two different boards (one using an STM32F7 and the other using STM32F3). When attempting to program the boards (using an ST-Link provided on Nucleo/Discovery boards) i get various errors revolving around resetting.
Basically, when trying to "run" a program from STM32CubeIDE, with "Software system reset" selected, depending on the debugger I use, I get:

for ST-Link GDB:

STM32_AppReset(), failure reset target.

for OpenOCD:

undefined debug reason 8 - target needs reset
Info : accepting 'gdb' connection on tcp/3333
undefined debug reason 8 - target needs reset
Error: timed out while waiting for target halted
Error executing event gdb-flash-erase-start on target STM32F373CCTx.cpu:
TARGET: STM32F373CCTx.cpu - Not halted
Error: Target not halted
Error: failed erasing sectors 0 to 10
Error: flash_erase returned -304

The only way to program the MCUs is to use ST-Link Utility, set it to Hardware Reset (because it won't even connect to the MCU when using Software System Reset), program the MCU and then manually power cycle it. If there is already a program in MCU memory, the ST-Link Utility will fail. The failures are different for the F3 and F7. On F7 it will just say that it cannot reset target, and on F3 the output is:

13:06:09 : Device ID:0x432
13:06:09 : Device flash Size : 256KBytes
13:06:09 : Device family :STM32F37xx
13:06:26 : The elf loader Program function fails.
13:06:28 : The elf loader Program function fails.
13:06:28 : Memory-Loader error
13:06:28 : Error occured during program operation!
13:06:28 : Programming error @ 0x08000188!

I am not sure whether it's a software problem or a hardware one. Regarding my connections, on both boards I'm only using SWDIO, SWCLK and GND. The MCU is getting stable 3.3V on both boards. There is no reset button, on both boards the NRST pin is connected directly to 3.3V. I've tried adding a 100nF capacitor between NRST and GND to make sure there won't be a drop from 3.3V but that didn't change anything.
As input protection there are 100 ohm resistors on SWDIO and SWCLK lines, there were also TVS diodes but I have removed them while trying to find a solution (and it didn't change anything). I've also tried several different ST-Link devices, but it did not have any impact.
I hope I have provided all the necessary details, cause I've been pulling my hair out over it for hours and could not find a solution. I have designed several other boards with the exact same connection scheme (only SWDIO and SWCLK, 100 ohm resistors etc.) and had no problem programming and debugging them. At first I thought that one F7 board was faulty, but the same problem persists on different PCB with a different MCU which suggests that I might be making a bigger mistake.
Thank you very much in advance.


texts: How do I calculate the max pwm frequency my h-bridge can handle?

texts:
my configuration:
H-bridge with 4 n-ch mosfets (IRF1405) with a gate capacitance of 5480pF and turn on delay time 13nS. I am using a hip4081 as my driver which has a peak current of 3.8A! This is how I am calculating the max pwm frequency my circuit can handle:

V=IR---(1)
t=RC---(2)

from (1) R=V/I plug in (2) => t=(V/I) * C
where
V=Gate Voltage (10V)
I=Max gate current (3.8A)
C=Input gate capacitance (5480pF)

plugging these values I get t = 14.4 nS. now this is the time it will take to charge the gate capacitance and so my pwm frequency should be < 1/t?

does this sound right? Please add your insights.

EDIT
Load is a wheelchair motor
Power = 150 - 450 W
Voltage = 24VDC
I = P/v = 7A - 19A


texts: Split current load through different wire

texts:
I have to power an electronic board with this flat wire band. But the problem is, the maximum current load is way more than a simple wire can held (1.7A). Each wire of the band is 28AWG with a current rating of 0.7A according to this file.

How many wire for VCC and GND do I need? \$ \frac{1.7}{0.7} + 1 = 3 \$ wires? Or is there more calculations to do?


texts: How does fluorescent lamp produce audible sound when blinking?

texts:
A fluorescent lamp will often blink near end of its life. Each time it blinks it likely produces a clearly audible sound which is hard to describe but it's something in between a water dip falling onto water surface and a mouse chirping.

How does it produce the sound?


texts: How to remove buzz from piezo speaker pickup?

texts:
I am using piezo speakers as pickup for my guitar. In one setup, for an amp,  I have a 25 year old Philips powerhouse aw636 stereo, which has a mic in. The problem is that when I connect the piezo to the mic in on the stereo, there is a buzz, and it goes away if I touch the negative tip of the jack.  A microphone from Philips works fine, without any hiss, but not the piezo by itself.

I was trying to remove the buzz/hiss from the setup using capacitors (trying to create grounding) but that never worked...

What can I do so that I don't have to connect my body to the jack -ve to remove the hiss?

The piezo pickups work fine without hiss when I connect them to the computer's mic in jack for amplification. The piezo in use a 35mm one.

EDIT:

One of the comments was an answer, that by Tony Stewart.

It says:

Use a large CM choke which balances the 2 wire impedance by raising CM Z while not raising differential Z.


texts: use craftmans 19.2 volt batteries for laptop?

texts: I invested in an Asus laptop for downloading and as a source for my music - From USB to spidif to DAC to amp.It sounds much better using battery power then the power supply.I would like more battery life-so was thinking of investing in a couple of craftmans 19.2V lithium batteries and charger and going that direction.Any opinions,information orideas would be appriciated.


texts:
i'm trying to create an airtight soldered mount for a pipe on a pcb depth sensor board I'm designing. To do this I am trying to create a custom pad in Altium that is a ring and is also plated. I've tried converting the ring to polygons, regions and cutouts. I've not been able to get any of them to become plated.

The picture might make this easier to understand. I want to put a plated ring of some sort in the empty ring as seen above.


texts: Are USB's Data+ and Data− needed when just charging?

texts:
Are the data + and − wires in a USB cable needed if you just want to charge something?

Also what are the benefits and drawbacks of removing the data + and − wires?


texts: Transistor activation / deactivation voltage in

texts:
The capacitor was allowed to discharge completely when the transistor was activated with the 3.4 V.

The capacitor is allowed to charge again when the conduction from the 5 V line through the resistor to the ground of the IC is open circuited because the transistor deactivated.

The transistor must deactivate at 0V to have the 5 second cycle. In the case that the transistor deactivated at 1.4 V across the capacitor, the 5 s cycle would be reduced to the time it takes to charge the capacitor from 1.4 V to 3.4 V.

So my question!:

If the transistor was activated at 3.4 Vin (3.4 V across the capacitor) and allowed the capacitor to discharge through it, then the voltage at the capacitor would be decreasing. V in of the transistor would not be 3.4 V anymore..

There is the mystery.

If The transistor activates at 3.4 V, then when does it close as it has current running through it from the capacitor to ground. The voltage across the capacitor would be 1 V at some time 't' , therefore the V in of the transistor would be 1V, which is less than 3.4 V, which is when it activates.

Does it deactivate at 0 V in - ~0 V in  AFTER it has activated (opened/activated), and only activate at 3.4 V in?

A second question: If I replaced the cap with a resistor the IC would switch rapidly correct?

The schematic on the top left is the one I redrew on the wide ruled paper.


texts: How to Find value of Early voltage of output characteristic curve of BJT?

texts:
I have this graph from data that I have. This is the output characteristic curve of BJT.
I want to find the value of early voltage VA?


texts:
So if I have AM, then to transmit information, I modulate the amplitude of energy peaks in a wave that has a frequency of say 10 kHz.

So normally, the individual peaks in the wave occurring at regular interals would be say 1 Volt high.  But by changing the height of the peaks to half volt quarter volt and every thing in between, and having someone tune in to the right frequency, they can hear my voice, because I am now changing their speaker energy output by changing the peaks in my carrier wave.

So SSB says, you can just change the troughs depths instead, or just the peaks height or whichever, it's all the same.

But then suppressed carrier SSB.  how can you suppress the carrier?. What are you modulating or changing the peaks of then? And how does the receiver separate your signal from other random noise, without a carrier to check for modulations on?


texts:
I have placed my first BGA on a PCB. I have followed the instructions from this video:

How to fanout a BGA - Altium Designer 16.1 - Joao Beck

The overall footprint of the BGA is much larger than the pad area and so my room does not totally encompass the entire component footprint. Regardless, my BGA fanned out nicely.

However, now when I run my DRC, I get the following error:

  Room Definition: Between BGA Component on Top Layer And BGA_Room (Bounding Region) (All)

Note: I also removed the default room from the schematic using this method.

What does this error mean? How do I resolve it?


texts: Are reference designs assumed to be license free?

texts: Can I use a reference design from a data sheet in a commercial product without attribution/licensing of any sort?


texts: Error in the minimum value of the operational amplifier output

texts:
I designed a circuit to control the speed of a 24V coller. For this I used the operational amplifier TCA0372DW.
As I am going to control the output voltage through a PWM signal that comes from the STM32, it was necessary to create an RC filter to convert the PWM signal into analog.
0% duty cycle = 0V
50% duty cycle = 1.65V
100% duty cycle = 3.3V
I determined the gain of the amplifier as follows: Vo / Vi = (R30 / R27) +1
With that I have a gain of approximately 7.3.
Theoretically for:
Vi = 0V ------ Vo = 0V
Vi = 1.65V ------ Vo = 12.045
Vo = 3.3V ------ Vo = 24.09
But this is not happening for input voltages near 0V. With the minimum input value I have at the 4V output and this affects the functioning of my system.
I know that there is a saturation in the amplifier that makes it never reach the maximum value of 24V. But I couldn't understand why for values close to 0V the output remains at 4V.


texts: Using step-up converter in metering instrument?

texts:
I am designing a pressure calibrator (my first Real project), which is supposed to measure from 0-200.00 mmWC (20000 counts) using Silabs C8051F350 (inbuilt 24-bit Sigma delta ADC). Sensor used is a typical Wheatstone bridge type Differential Pressure sensor.

This is the schematic to generate Bridge voltage (Vbridge) for the sensor.
ADC-Vref seems to very be noisy on DSO (few mVp-p).

In almost all our instruments, previous Engineers have freely used AD620 to condition differential pressure signal, however cost of that INA has now increased too much for us to throw it randomly in our circuit so we have resorted to following arrangement. Common mode rejection to be dependent on ADC's PGA's CMRR, which is stated to be typical 100 dB at 50/60Hz BW.

simulate this circuit – Schematic created using CircuitLab

So here's my first question: Is this ADC driver, Vbridge generation a viable method.
I mean is it going to give me good, less error, less noisy performance (because my step size with a 5mV full span sensor would be 0.25uV/step).

Sorry for using words like good and less, I can't speak actual number since noise voltage calculations and stuffs are above my head.

And my main concern is: We are deriving 5V from a single cell Li-ion and Boost converter(MCP1640) which also has few mVpp of ripple.

So is it an intelligent idea to use such a switching power supply in Analog sensitive instrument.


texts: What's the relationship between DC braking torque and AC turning torque for a given current on a BLDC motor

texts:
Given a 3-phase AC motor, it will have a torque vs AC current curve

The same motor will also start braking with a constant DC current through any two of the wires, again with the amount of braking torque proportional to the current

My question is for a given current, what is the relationship between the spinning torque caused by the AC current vs the braking torque caused by the DC current? is it a factor of 3 because only one of the three "phases" is being energized? does it involve a RMS-offset because of a constantly changing AC current? will it vary from motor to motor, or will it remain proportional across different motor configurations (# poles, magnet strength, etc.?)


texts: What are the technical specifications of Tesla "cell level fuses" one fuse per cell

texts:
How do Telsa cell level fuses work?

Can they protect against short circuits and internal cell fusing?

How is the current distributed throughout so many fuses? A total of 200 amps could pass through the 400 volt end, devided between all the fuses up to the 0 volt end?

What are the physics of that kind of electrical specification?

Are there fuses on the + and - of all cells?

What is the ideal specification of fuses for that use?

For the Tesla Model S:

7104 cells.
Panasonic 3400 mAh at 3.6V. capacity of 7104 * 3400 * 3.6 = 86.95 kWh.
The cells are arranged in 96 groups of 74 cells each.
The 74 cells in a group (also called a "brick" in the Roadster are wired in parallel so that the batteries are balanced amongst
themselves. Each group as one large approximately 4.1V cell with a
current capacity of approximately 230 Ah.
The 96 groups are connected in series, rendering a pack output of 403v at 230Ah.

perhaps unreliable: "Model S' optimal speed in comparison is about 140-160 km/h, with 118 kW peak power and 76 kW average to 80 %"


texts:
I have a question regarding local fiducials so as to achieve proper alignment of the board, during the soldering of a 0.4mm pitch chip. As I have seen the best practice for local fiducials is to place 2 of them, one on the upper right corner of the chip and one down and left. Due to lack of space I can only place one fiducial at the down left corner. Is this going to be helpful or useless? I have also placed 3 global fiducials for general board alignment.

Thank you


texts:
Wikipedia says that it is a idealized or physical device that implements the Boolean function.

By this definition I tend to think every digital circuits (say a counter or encoder) as a logic gate.

But it also says that "Logic circuits include such devices as multiplexers, registers, arithmetic logic units (ALUs), and computer memory, all the way up through complete microprocessors, which may contain more than 100 million gates". So according to this every complex digital circuit is not an logic gate but they are made up of logic gates.

Then I confused by the definition of logic gates. If multiplexer is not a logic gate then I tend to think XOR gate also not as logic gate. Can anyone explain this?


texts: Problems with dividing a clock with 2 command bits

texts:
I am trying to make a clock divider commanded by 2 bits :DTPS.
For instance if DTPS is:

"00" we get the clock as output(2^0)
"01" we divide the clock by 2 (2^1)
"10" we divide the clock by 4 (2^2)
"11" we divide the clock by 8 (2^3)

So i had 2 problems the first is when DTPS is "10" divison becomes 11111111111111111111111111100 I don't know why.
and the second problem is that I manged to get an impulse when the DTPS ="01" but i could not make a full signal which the division of clk.

Please review my code and tell me what I i did wrong and how could the right thing that I did be improved as well as my coding style.

Thank you very much.

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
Use ieee.std_logic_unsigned.all;
USE ieee.numeric_std.ALL;

entity diviseur2n is
     Generic (Nbits : integer := 8);
    Port ( rst : in STD_LOGIC;
           clk : in  STD_LOGIC;
           DTPS : in STD_LOGIC_VECTOR(1 downto 0);
           tc : out STD_LOGIC);
end diviseur2n;

architecture architecture_diviseur of diviseur2n is

signal cpt : std_logic_vector(Nbits-1 downto 0);
signal division : integer;
signal cpt_full : std_logic;

begin
    process(clk)
      begin
        if DTPS="00" then
            division <= 1;
        else
            division <= to_integer(signed(DTPS))*2;-- value of DTPS into decimal then *2 to get 2^n= divison
        end if;
    end process;

  -- compteur 0 a division
  comptage: process(clk,rst,division)
  begin
  --cpt_full <= '0';give this error: Signal cpt_full cannot be synthesized, bad synchronous description. The description style you are using to describe a synchronous element (register, memory, etc.) is not supported in the current software release.

   if rst = '1' then
     cpt <= (others => '0');
      cpt_full <= '0';
   elsif rising_edge(clk) then
    if cpt < division then
        cpt <= cpt + 1;
     else
        cpt <= (others => '0');
          cpt_full <= '1';
     end if;
    end if;
  end process comptage;

  -- impulsion de sortie a division
  retenue: process(cpt_full)
    begin
        if cpt_full='1' then
            tc <= '1';
        else
            tc <= '0';
        end if;
    end process retenue;

end architecture_diviseur;


texts: Testing a video transmitter for video bandwidth

texts: I need to test the bandwidth of a variety of video transmitters to figure out the maximum resolution I can safely output without losing detail. To this end, I came up with a solution using a TV pattern generator to generate a proper PAL or NTSC video signal with colour bars or with just blackness, and a 10 MHz signal generator, to generate a pixel clock. However, the 10 MHz signal generator is too expensive for a student like me - about £300 here. The TV pattern generator is only £75, which I can afford. I need a way to generate an adjustable square wave signal from 5 MHz to about 12 MHz, synchronised with a video signal. The frequency doesn't have to be precise, because I can verify it with an oscilloscope. I just need to see the point at which a typical video TX can handle no more pixels, because I have the opportunity to make a high resolution on screen display - but it doesn't matter if no-one can see the pixels!


texts:
Consider the following circuit where i(t) is sinusoidal and exists across both components. (1) is an inductor and (2) is a capacitor. The ideal voltmeters measure effective value. What is the value measured by V2:

The correct answer should be 2V

My attempt.
I know we can only apply KVL using phasors. The current phasor should be $$Ie^{j\theta}$$

The voltage across the inductor is $$\omega LIe^{j(\theta+\pi/2)}=V_1e^{j(\theta+\pi/2)}$$
The voltage across the capacitor is $$\frac{I}{\omega C}e^{j(\theta+-\pi/2)}=V_2e^{j(\theta-\pi/2)}$$

And the voltage across both components $$(\omega L-\frac{1}{\omega C})Ie^{j(\theta+-\pi/2)}=Ve^{j(\theta+\pi/2)}$$

And so applying KVL we get to

$$Ve^{j(\theta+\pi/2)}=V_1e^{j(\theta+\pi/2)}+V_2e^{j(\theta-\pi/2)}$$
$$Ve^{j\pi/2)}=V_1e^{j(\pi/2)}+V_2e^{j(-\pi/2)}$$

And dividing everything by $$\sqrt{2}$$

$$V_{eff}e^{j\pi/2)}=V_{1eff}e^{j(\pi/2)}+V_{2eff}e^{j(-\pi/2)}$$

Substituting by the known values

$$1e^{j\pi/2)}=1e^{j(\pi/2)}+V_{2eff}e^{j(-\pi/2)}$$
$$0=V_{2eff}e^{j(-\pi/2)}$$

And so $$V_{2eff}=0$$.

However the correct answer should be +2V.

Can someone help me to figure out my mistake? It's probably a conceptual mistake.


texts: How do we measure capacitance by change in vibration

texts:
A capacitively based MEMS affinity glucose sensor.

link to the IEEE paper, from where I've got this doubt.

The gold electrodes are separated with some distance and the permalloy is vibrating with the help of solenoid(it generates a time-varying magnetic field[solenoid is not shown in the image]). Glucose comes inside through the semipermeable membrane and makes the liquid in which the cantilever is there more viscous which reduces the vibration in the cantilever. We measure the capacitance created by the gold electrode.

Question: How does the capacitance changes when the vibration of the permalloy slows down?


texts: How to analyze this diode circuit for a resistance?

texts:
I'm sorry for posting a textbook question, but it does not provide any explanation and I am pulling hair trying to make sense of this.

I tried converting each of the diodes to a 0.7V DC source with positive terminals up. Then I thought I found the equivalent resistance of the 3 diodes by

Rd = Vd/Id = (0.7 * 3 V)/(1 mA) = 2100 ohms

Then I did a voltage divider

Vo = Vin * Rd / (Rd + R)

Rearranged for R

R = Vin * Rd / Vo - Rd

Plugged in the values

R = (10 - 0.7 * 3) * 2100 / 2.4 - 2100
R = 4812.5

Which isn't even remotely close to the supplied answer of 139.

I've been at this for over an hour and I'm too stubborn to ignore it but obviously not learned enough to figure it out yet. Can you help me see what I'm missing?

EDIT: Full Solution

$$ I = I_s e^{\frac{v}{v_t}} $$

$$ I_s = \frac{I}{e^{\frac{v}{v_t}}} = \frac{0.001}{e^{\frac{0.7}{0.025}}} \approx 6.914 \cdot 10^{-16} $$

$$ I = I_s e^{\frac{v}{v_t}} = (I_s) e^{\frac{2.4 / 3}{0.025}} = 0.0546\, A $$

$$ R = \frac{v}{i} = \frac{10 - 2.4}{0.0546} = 139 $$


texts: Can I make my USB to serial adaptor imitate a null modem cable with a straight cable?

texts:
Is there a way in software to make a USB to serial adaptor work like it is using a null modem cable while it is actually using a straight through cable?

(Using an off-the-shelf USB to DB9 adaptor for RS232 under windows).


texts: Converting Bin-to-BCD code from VHDL to Verilog

texts:
Hello guys I am trying to translate following VHDL code to Verilog, however it does not work even if they look like pretty same. I get no errors however it is not working with Verilog one but works with VHDL one. Can you guys please help me to work out this problem?

VHDL Code (working)

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.std_logic_unsigned.all;
use ieee.numeric_std.all;
entity binbcd8 is

port(
b: in unsigned(7 downto 0);
p: out unsigned(9 downto 0)
);
end binbcd8;

architecture Behavioral of binbcd8 is

begin

bcd1: process(b)
variable z: unsigned(17 downto 0);
begin
for i in 0 to 17 loop
    z(i):='0';
end loop;

z(10 downto 3):=b;

for i in 0 to 4 loop
    if z(11 downto 8)>4 then
        z(11 downto 8):=z(11 downto 8)+3;
    end if;
    if z(15 downto 12)>4 then
        z(15 downto 12):=z(15 downto 12)+3;
    end if;
    z(17 downto 1):=z(16 downto 0);
end loop;
p<=z(17 downto 8);

end process;
end Behavioral;

Verilog code (not working):

 module binbcd8(input[7:0] b,output reg[9:0] p);
 reg[17:0] z;

 integer i;

 always@(b)
     begin
         z <=17'b0;
         z[10:3] <=b;
         for(i=0;i<4;i=i+1) begin
             if(z[11:8]>4)
                 z[11:8]<=z[11:8]+3;
             else
                 z<=z;
             if(z[15:12]>4)
                 z[15:12]<=z[15:12]+3;
             else
                 z<=z;
             z[17:1]<=z[16:0];
         end
         p<=z[17:8];
     end
 endmodule

It does not work. Can you please help me?:


texts: Combining an Audio Signal and 9 VDC on the same Trace

texts:
I have a backplane where 4 individual modules plug into it and provide various sound effects. To control which module is powered and to route the input signal to it, there is a 2-pole, 5-way mechanical switch so the power and signal are sent to the desired module. However, the output signal from each module shares the same trace going to the amplifier.

This is a problem because when more than 1 module is plugged, in the output signal goes south. Individual modules work great, but with more than one module installed, not so good. I thought that since the other 3 modules were not powered they would have no effect on the active module, well, I was wrong.

So I was trying to think of a way to route the input signal and power to the appropriate module and separate the output signals so they are not in parallel. That led me to see if I can use one of the poles of the switch for both power and input signal and the other pole for the output signal.

Two other thoughts were to add a diode to each of the output traces or an audio transformer. I just don't know, I already have hardware built so I am stuck trying to make what I have to work.

Do you think this will work or have any suggestions about the idea of adding the power to the input signal?


texts: a strand of usb cable is yellow not black

texts:
I cut the wire of a USB keyboard to supply 5V power to my Arduino. I expected to find Red wire for +5V, Black for GND, White for D-, and Green for D+. However, there is no Black, instead, there is a yellow wire! (I cut off the mouse cable too, but it has the same colors.)

I suspect that yellow wire is playing a role of black.  So I connected the yellow wire to a LED's short leg (cathode) and red wire to LED's longer leg (anode).  But, no light was emmitted.

When I tried yellow wire as -5V and white one for +5V, it works, but it is blinking.  I understand this to mean that this is not stable power.

If I want to take stable 5v power from a USB port to illuminate an LED, what colors should I use?


texts: Why does my ground pour cover up everything else? (Eagle)

texts:
Platform: Mac OS X 10.13.5
Eagle Version: 9.1.1

For some reason, when I apply my ground pour (draw polygon with name GND and hit ratsnest), the ground pour covers my other components as well as air wires in the Eagle board view.

I don't think I experienced this with other board designs.

Is there something that I'm doing wrong?

Edit:
This is what it looks like in an Eagle tutorial:


texts: True replacement for MOSFET Infineon SPD04N50C3

texts:
I have built many 240V AC dimmers with back-to-back Infineon SPD04N50C3 N-channel MOSFET transistors without any problems. Unfortunately they are not manufactured anymore.

I found a replacement from ST STD7NM60N. I believed that is a perfect replacement, not seeing any real differences in the specification.

Something must be different, because sometimes when I turn on the 200W bulb, using the same PCB and the same production software, one of the MOSFETS goes permanently short. This happens in about every 100 turn-ons.

Schematics:
https://www.dropbox.com/s/fdekeblcch6gt3f/dimmer_dev.pdf?dl=0

Looking with oscilloscope, the gate driving PWM signal looks pretty good. Same is true for the AC wave.

Can anybody tell me, why is that, more precisely, which parameter in the specification is weaker? Pinpointing it would help me to look for a better replacement.

Price is an issue. Both MOSFETs cost about $0.50/pcs, there is no budget to go much higher.

Gate is driven via 22 kohm resistors directly from PIC microprocessor. Because the low budget, and because the desire is to drive the gate with as high voltage as possible, we have PIC powered with 5.5V instead of normal 5V, thus gate voltage is also about 5.5V PWM control. MOSFET is switched ON at every AC zero crossing, and turned off within the half-wave dimming level dependent.

Thank you so much for your time.

Link to Infineon MOSFET:
https://www.infineon.com/dgdl/Infineon-SPD04N50C3-DS-v02_06-en.pdf?fileId=db3a30433f12d084013f19f2e04218fd

Link to ST MOSFET:
https://www.dropbox.com/s/9dxv59lpdu3vseg/tran_STD7NM60N.pdf?dl=0
or another
https://www.st.com/resource/en/datasheet/std7nm60n.pdf


texts:
I am designing an SPI system with one master and two slaves. In a normal SPI system, the master needs 2 outputs to control the slaves' chip select lines. I want to use only one output to drive both chip selects thanks to a classic NOT gate.

simulate this circuit – Schematic created using CircuitLab

I haven't tried this yet because I see one issue:

When the master command comes from HIGH to LOW, both chips will be selected for a short time due to the NOT gate delay.

Can this issue cause an overall problem?

Edit:

For this easy scenario, a "not" gate does the job, what is commonly used when there are many more slaves? MUX?


texts:
In the figure shown, Vi is a 100 hz triangular wave having a peak to peak amplitude of 2 volts and an average value of 0 volts.
Given that the diode is ideal, the average value of the output voltage Vo is ________.

My attempt.

I took an assertion that at the moment when the input voltage is 1v(it's maximum), the diode is reverse biased.
Then using voltage divider, the voltage across the resistor turned out to be Vi/2 i.e 0.5 volts.
Voila ! The assertion is indeed correct.

That means the output voltage will just be a copy of the input voltage dimnished by a factor of 1/2.

I.e a 100 hz triangular wave having a peak to peak amplitude of 1 volts.

Therefore, the average value of the output voltage is zero.

Is this answer correct ?
And if yes, can we also take the opposite assertion assuming the diode to be forward biased and then prove it wrong. If yes, how ?


texts:
This is my latest attempt to try building a ups ish system for my 3D printer
the printer is custom-designed with 5 meters (no, it's not a typo) on each axis.

we use MKS Gen v1.1 with custom marlin core.

this board can handle 12-24v.

with our calculation, our current draw is 20 to 60 amps when bed and nozzle are heating up.

so a commercial UPS is not affordable.

I came up with the following circuit as our power source.

I could use some tips to optimize it.

simulate this circuit – Schematic created using CircuitLab

I know it's not pretty

My charge controller is Arduino Mega with the following algorithm:

if the battery voltage drops below 11.5 the relay is connected to charge the battery up to 13 volts then the relay is disconnected.

V1 is a power source with 80 amps capacity.

V2 is 3 car batteries connected in parallel. (to handle the sudden current shock)

There is a backup generator behind V1 which starts if V2 drops below 11.2.

There are other loads on the printer side that are mission-critical and can not be turned off even for 1 second.

P.S: I was thinking about adding a capacitor to smooth out the voltage but I could use a bit of help to calculate its capacity.

P.S2: we are planning to add solar panel as V3 later this year...

P.S3:  I know, I know its idiotic, but we are tight on budget and cannot afford a big UPS we are pretty much out of money and this printer is our income source ...

( it took me around 35 days to build this printer, speed is 3mm/min, it's huge )


texts:
What current does it consume during serial programming? According to datasheet it’s about 6000uA at 3.3V. I have to power it from a 10mA ldo, but now I’m not sure that it will be enough.
To keep circuit simple I decided not to use external voltage source ( e.g from usbasp)
Would here be some problems if I connect two voltage sources without any protection - the internal ldo and an external source? With the same voltage of course.
Thanks beforehand.


texts: What does "Low density device" mean? About STM8 / STM32

texts:
STM32 and STM8 devices have some types:

Low density devices
Medium density devices
High density devices

About what "density" mean?
About quantity of periphery or about quantity of flash or something else?


texts: How can one increase the IP3 of a low noise amplifier (LNA)?

texts:
Is lowering the gain of an LNA the only method to increase IP3?
Is there any other technique to increase IP3 without sacrificing the gain?


texts:
Is there specific standard ways to generate clocks from oscillators? Referring to generating a square-wave clock from a sinusoidal oscillator output.

I can think of a few circuits involving diodes as well as using a chain of op-amps as comparators that could produce a square wave.

However, both have drawbacks, such as the voltage reference in a comparator drifting resulting in jitter on the output clock over a temperature range.

Are there industry standard schemes for creating clocks from an oscillator output?


texts: Why am I getting an error in my transfer function?

texts: I'm trying to solve part b here, and my transfer function is coming out as $$\frac{-1.25s}{s^2 + 2.05s + 1}$$ instead of the given $$\frac{-1.25s}{s^2 + 1.6s + 1}$$. Since there were no initial conditions, I just transformed the capacitors to impedance \$1/s\$ and applied KCL at the node. What am I missing? My working is below as well, I can't see where the problem lies.


texts: PWM Modes: Center Aligned and Left Aligned (current consumption)

texts: I have a question about PWM in STM32F051xxx Microcontrollers. I want to know if there is a difference regarding the current consumption of the microcontroller between the center aligned mode and edge aligned mode?


texts:
I followed some examples and I already managed to make a big S2MM (stream to memory-mapped) transfer via an AXI DMA.

However, now I'm trying the reverse, i.e. to make a simple MM2S transfer to a very simple IP block that I made and the result returned from the block is wrong. Note that the MM2S code is also almost a copy from examples that I found.

I tried debugging with the ILA(integrated Logic Analyzer) tool from Vivado and the result is in attachement.

Can you help me understand why I'm writing the following values:

static void initialize_parameters(u32 SrcAddress){
u32 *BufferPtr;
union float32 thisfloat;

BufferPtr=(u32*)(SrcAddress);
thisfloat.f32=10.0;
BufferPtr[0]=thisfloat.u32;

thisfloat.f32=0.0;
BufferPtr[1]=thisfloat.u32;

thisfloat.f32=10.0;
BufferPtr[2]=thisfloat.u32;

thisfloat.f32=20.0;
BufferPtr[3]=thisfloat.u32;

}

and making a transfer like this:

// Kick off DMA transfers
Status = XAxiDma_SimpleTransfer(&axi_dma, PARAMETERS_ADDR, 4*4, XAXIDMA_DMA_TO_DEVICE);

and the signal parameters_TDATA when tvalid=1 is that thing that we can see in attachement? Also, the final result is incorrect.
What am I doing wrong?

Also, here's a print screen of my block design in Vivado.
Note: I'm working on a Zedboard


texts: Efficiently decoding a four bit input pattern into one of 16 twelve-bit output patterns

texts:
I have a four-bit input pattern.  I have 16 distinct 12-bit output patterns.  Many of these output patterns have a bits which are set in 2 or 4 of patterns.

If I (arbitrarily) assign each pattern to a four-bit number, I can use various online Karnaugh map tools to generate logic circuits.

This arbitrary assignment of patterns to four-bit numbers adds unnecessary constraints to the problem.

Is there a way of solving this, to give the best pattern<->number assignments, other than by brute-forcing all 16! orderings?

(Where "best" is the pattern<->number assignment which requires least logic to decode the four-bit input one of the 12 bit output patterns.)

Update:

Here are the bit patterns I want to decode a 4-bit numbers to:

0  0  0  1  0  0  0  0  1  0  0  0
0  1  0  1  0  0  0  0  1  0  0  0
0  0  0  0  0  0  1  0  1  0  0  0
0  0  0  0  0  1  0  0  0  0  0  1

0  0  0  0  1  0  0  0  0  1  0  0
0  1  0  0  1  0  0  0  0  1  0  0
1  0  1  0  1  0  0  0  0  1  0  0
0  0  0  0  0  0  1  0  0  1  0  0

0  0  0  0  0  1  0  0  0  0  1  0
1  0  0  0  0  1  0  0  0  0  1  0
0  0  0  0  0  1  1  0  0  0  1  0
0  0  0  0  0  0  1  0  0  0  1  0

0  0  0  0  0  1  0  1  0  0  0  0
0  0  0  0  0  0  0  0  0  0  0  0
0  0  0  0  0  1  1  1  0  0  0  0
0  0  0  0  0  0  1  1  0  0  0  0

It does not matter which four-bit number decodes to which 12-bit pattern, provided there is a one-to-one relationship.

What are the fewest logic gates which will do the job?

While solving the above may be marginally useful, it is the general solution that I am looking for.


texts: Compiling Linux for an H8/532 microcontroller?

texts:
Can I compile and run Linux on an H8/532 microcontroller? From what I've read, it is possible for some of the models.

Family: H8

Specific Model: HD6475328CP10

Research

http://lkml.iu.edu/hypermail/linux/kernel/1506.2/05292.html
http://pdf.datasheetcatalog.com/datasheet_pdf/hitachi-semiconductor/HD6475328CP10.pdf


texts: How to simulate parasitic reactances in a circuit

texts:
Does parasitic capacitance of a microstrip trace add to the value of a physical capacitor on the same trace?

If one sees it as a series element, then it would seriously reduce the value of all capacitors that has a bigger capacitance value than the trace. If one sees it a parallel element, then the trace capacitance would add to the value of the capacitor. I guess the latter must be right, but I'd really like to get some opinions on how this works.

The same goes for inductors.


texts: Why can't a multimeter measure its own current and voltage?

texts:
Well I finally obtained another multimeter, so now I have a Mastech MS8226T and a Ben Electronic M92A. I decided to measure at which voltages would the low battery warning appear and how much current each of them consumes.

So here's my setup: Power supply->M92A->9V plug->MS8226T->other end of the 9V plug->power supply.

I used M92A to measure current and wanted to use MS8226T to measure voltage. Unfortunately, I couldn't measure the supply's voltage using MS8226T. I always got 0 V. When I swithched the meters, M92A would show voltage out of range for every scale.

So I decided to use the powered on meter to measure current and the second meter to measure voltage. I got zero as result on both meters, when I wanted to use them to measure their own curent consumption.

Why is that so?

EDIT
Here are the schematics.

 On this image, XMM1 is the meter measuring current and it is powered by its battery. Meter XMM2 is powered by the power supply V1. I used R1 as the meter's power plug. When I use MS8226T as XMM2 in such a set-up, I get zero volts on the supply. When I use the M92A, I get out of range on all ranges. The XMM1 meter shows expected values.

On this image meter XMM1 is powered by its internal battery, is measuring voltage and shows expected values. Meter XMM2 is measuring current and reads zero. I'm using resistor R1 instead of meter's power plug here.


texts:
I am using the L298N motor driver for a robotics project to control 4 motors. 2 in each input and output terminal. I have this connected to an arduino uno which is powered by about 7-8v from nimh batteries. This battery source also powers a servo with a 470uF capacitor and the L298 board. Finally i also a have a hc sr04 running of the 5v rail.

I have a program that makes the servo sweep left and right. When the servo is moving however ,very little current is going into the L298 and only one or two motors are moving when all 4 should. When the program is only controlling the motors and not servo the servo keeps twitching and turns to face the left (0 degrees) and slows the motors down. Why is  the servo conflicting with the dc motors?


texts: Red divider resistors for 5050 RGB strip coming from WS2811 chip

texts:
To split up a WS2811 data signal into discrete 5050 RGB 12V LED signals, I followed the example on the WS2811 datasheet and hooked up its outputs to a separate power supply.

This example shows one divider resistor on the red LEDs which is how I built my circuit. After doing research, I discovered that 5050 LED strips actually require a resistor for every color. So now I'm wondering if I built my circuit wrongly.

The 5050 LED strips are usually not very long, varying from 2 LEDs to 24 LEDs in total. Should I assume these components have their resistors built in already? Should I still add additional resistors and what value should they be? Or should I only add resistors to plain RGB LEDs which I will hook up?

Thanks in advance for any help!

Here's the electrical characteristics of the WS2811:

And here's that of the 5050 RGB spec:


texts: How to convert a wide voltage range (1 V-12 V) to 5 V?

texts:
I have an unusual application where the input voltage can vary from 1-12 V DC. This must be converted to 5 V @ ~200-250 mA.

Since there are no available buck-boost converters suitable for this wide input voltage range, I came up with this (simplified) circuit:

simulate this circuit – Schematic created using CircuitLab

The XC61CC5002MR-G is a voltage CMOS supervisory IC which:

Outputs VCC when VCC > 5 V - this enables the LDO and protects the
boost converter from the higher voltage.
Outputs 0 V when VCC < 5 V - this disables the LDO and biases the PMOS transistor to allow current to the boost converter.

The boost converter's absolute maximum voltage rating is 6 V, so it needs to be protected at the higher range of input voltage, whilst the LDO is OK up to 13 V.

The circuit worked as intended from 3-12 V, however the PMOS transistor couldn't switch when the input voltage was lower than 3 V, which shouldn't have surprised me since the VGS threshold was about 2 V at 250 mA.

I have also looked at high-side load switches and over-voltage protection ICs, but I cannot find any that will operate over the whole range of the input voltages after browsing for hours on Mouser and DigiKey.

Lastly I have explored using a N-channel MOSFET in the circuit above with an open-drain output variant of the same supervisory IC and a charge pump to bias the NMOS transistor when voltages are low, but to my surprise I couldn't find any charge pumps that work in the 1-5 V range.

I am looking for any suggestions to either make my circuit work with the lower voltages or how else I can achieve this 1-12 V to 5 V conversion without dramatically increasing the PCB footprint or cost. Unfortunately the input voltage cannot be changed, but the power supply can provide more than enough current to run the circuit.


texts:
I would like to design a system that produces -10 degrees and +10 degrees phase shifts at 409.6MHz (Basically BPSK).

The way I'm thinking about approaching this is by using a DDS to generate the BPSK at 12.8MHz and up-converting using a mixer to 409.6MHz, filtering, and amplifying to +10dBm.

Is this the best way to do this? I have also read that I can use a 32x PLL multiplier... would that be a better way?

Factors I am taking into consideration:

Complexity to design circuit/pcb
Cost of components
Low phase noise, low spurs, emi, etc.
Using a 12.8MHz ovenized oscillator (as 12.8 x 32 = 409.6)


texts: Flattening microphone's frequency response

texts:
It is typical for a microphone to have a non-flat frequency response like so:

Is it typical to flatten the response curve by weighting the signal in frequency domain to get the most accurate representation of measured sound?

If not, then why?

If yes, then why don't manufacturer ever provide the response curve in numerical form?


texts:
What's a reliable method of getting a clean measurement of the potentiometer in a hobby servo?

I've modified a servo for directly polling its position by soldering a wire onto its potentiometer's center lead, as described here. I then wired this lead to an Arduino's ADC pin, but I'm finding the readings to be extremely noisy even when the servo isn't moving. I tried using a moving average to smooth the signal, but even that results in jittery value.

Is this just the nature of a servo's potentiometer, so is there a better way to wire to clean the measurements?

Edit: By "noisy", I mean even when the servo wasn't moving, the ADC measurement taken by the Arduino could vary by ±50 units between readings.


texts: Time taken by an alternating quantity to reach a particular value for the second time within one cycle

texts: How do we find the time taken by the current i=20sin(314t) to reach a particular value( not 0 or the peak value) for the second time within one cycle


texts: ATmega328 decoupling caps: are they in right position?

texts:
I'm designing a PCB layout with an ATmega328 + NRF24. I know perfectly the need of the decoupling caps, C1 and C2 in my image.

My trouble is following: VCC coming from battery (with a 0.1 µF in parallel).

You note that VCC cross C1 (1206 ceramic 0.1 µF) and goes to pin 20. From C1 VCC goes to pin 7 and from pin 7 on the other decoupler capacitor (C2, again 1206 ceramic 0.1 µF).

Is it right OR I need divide the VCC in two branches, every one "going" to one cap?

To explain, this is other layout:


texts: Buck Converter Feedback Loop - Stability Criteria

texts:
Question 1 :
I am having some trouble understanding the Stability criteria of the Buck Converter Loop Stability which says, "The cross over frequency should be less than 1/8th or 1/10th of the switching frequency ".
Can someone tell me with the switching frequency pulse waveform and the cross over frequency waveform - on why the cross over frequency should be less than 1/8th or 1/10th of the switching frequency.
I think it would be clear if someone shows me the waveforms of the switching frequency and the crossover frequency and explain with the above criteria.


texts: Will this wall wart supply enough power?

texts:
I am building a little pen plotter.

It is powered by a 12V 1.0A wall wart, as well as by a standard USB connection.

There is an Arduino Duemilanove, which will draw 120mA for the Atmega328 as well as 50mA for the control pins.

Attached to the control pins are three Easydrivers, that are supposed to draw 150mA apiece, and they are connected to stepper motors with 6 Ohm windings. these easydrivers are powered from VIN.

Also powered from VIN is a 12V 2.08W fan, which will run continuously.

Will this run without blowing something up?


texts: How do I implement TDMA with basic 433 MHz transmitter receiver pairs?

texts: Is it possible to use TDMA or some kind of time synchronization / pseudo random coding for a number of transmitters so that they can be interfaced with a single master receiver without jamming?


texts: How can I determine how much power my solar panel outputs during winter?

texts: Hi I have a circular shape 7cm in diameter solar panel rated at 5.5V 80mA = 440mW. My question is how much power would it output on average during the winter when there is about 8 hours of day light? do I need to find out how much lumens there are per day in winter and convert it into Watts, if so could someone please assist me on doing so.


texts: What kind of power supply filter is this?

texts:
I found this filter in an inherited design. It is supposed to filter some noisy input (around 13V) coming from a generator.
I'm new to designing filters and coils but something feels off here - I kind of expected a resistor for a low-pass. Is this some kind of standard filter against voltage spikes? I did not find any documentation for this.
The reason I'm asking is that recently I got a board back where D1 was burnt and I'm looking for ways to improve this.


texts: Use and charge a Lithium battery at the same time

texts:
I have read this question and its answers : How a battery is being charged and used as the same time?
Question 1 : I would like to know if the same concept can be applied to Lithium battery.
Question 2 : Let's say that the battery is being used, I plug the charger, what happens at this special moment, electrically speaking ?
My use case is this : I built a portable speakers box, a Lithim battery is inside (24V and 18Ah). I have a charger that delivers 24V and 5A. The little amplifier inside can use up to 5A. I want to know if there is no risk from plugging ang unplugging the charger when the music plays.
Schematic diagram of my use case :

Constraint 1 : The vuemeter must not work when the system is OFF.
Constraint 2 : The charger must charge the battery when the system is ON and OFF.
Constraint 3 : The charger must provide the charge to system when it is plugged, instead of discharging the battery.


texts: How many layers at least for proper DDR3 fanout and routing?

texts:
I'm working on a project and have been banging my head against the wall for the past couple of weeks with the DDR3 fanout and wiring. I'm trying to keep the cost to the minimum, so I'm using the most cost-effective DDR3 IC's I managed to find, which is 512Mb x16 96-ball packages by Kingston and have four of them connected to an ARM Cortex-A7 CPU. Since I've entirely rerouted the memory subsystem abt a dozen times, trying to fit everything on a 4 layer board with components only on one side (for cost and aesthetic reasons), I decided to check how many layers other people have used for similar projects? As far as I can tell by the laminate of some SBCs I have, others have used at least 6 layers for this. Some seem to go for single chip twin- or quad-die 32x options, but that stretches the production costs by a lot, and I'm trying to keep the costs down.

Has anyone succeeded in routing 2 channels with 2 x16 chips each on a 4-layer PCB, with proper length and skew tuning? I would go for 6-layer PCB, but the price jumps almost twice, and I'm already stretching my wallet with the 4mils(0.1mm) track width and 8mils(0.2mm) via holes. Going to 6 layers, the price hike is significant regardless of the track widths and min drill sizes used.

Any suggestions how to do this better and more efficiently?

Thanks in advance!

vlex


texts: Battery to AC conversion of faucet IR sensor

texts:
I bought this faucet which includes a hand IR sensor, but it's battery powered. I wanted to convert it to AC power using this excellent Video as a guide. Since it takes 4 AA batteries, I bought an old Aiwa 6V cell phone charger and followed the instructions to use it as my power source. I wired white to + and black to - and carefully observed the polarities when connecting to the battery compartment.
Upon connecting it, the faucet IR sensor LED started blinking rhythmically and was not responsive to hand gestures. When I replaced the dummy batteries with real ones, it works fine. That is, the LED flashes once with each hand toggle action.
It's probably hard to know why without knowing the specifications for the faucet system, but is there an obvious explanation why my custom power supply would cause the box to respond this way?


texts: High Pass vs Low Pass simple Circuit (RC vs CR)

texts: In an RC circuit, where the resistor comes before the capacitor, the circuit acts like a low pass filter. Whereas in a CR (I don't know if that is how you say it) circuit, where the capacitor comes before the resistor, the circuit acts like a high pass filter. Why does using the same capacitor just in different order relative to the resistor change the filter type? Thank you!


texts: Are the USB-C D+ and D- shorted to its duplicate pair pin?

texts:
Is the usb type C connector Data + and Data - are shorted to its pair on the opposite side?
Are the Vbuses shorted to the other V buses?
And does the question above still hold true/false if the cable is type-C to type-A or if the cable is type-C to type-C?


texts: Control multiple LEDs using an IC and PC/Linux thru USB

texts:
I've already tried to search this topic but all Google results said that this isn't possible. Is there any chance of controlling multiple LEDs using a PC/Linux, through USB? The diagram might look like this:

This is just a made up circuit I created. Resistors, capacitors, Inductors, or any other components might be included in the real product.

In detail, an application is able to send data to the IC, and the IC in turn will turn on the LED. In the application, the user can choose which of the LEDs are turned on and off.

What IC or ICs do I need to use to receive data from the computer via USB? And what programming language do I need to use to control the IC? Or what other components do I need to use to make this possible?

***PS:
IT is more like a Raspberry Pi controlling LEDs to turn on and off thru its header pins. But in this mattter, USB will be the mode of connection and I will be the one who will create the circuit(and the application).


texts: Building a 7 Segment clock using mains frequency

texts:
As the title says, I want to build a clock using the mains frequency (50Hz). I only want to use digital integrated circuits from the CD4xxx series or something similar. (no microcontroller or do-it-all IC)

I plan on using a transformer and a comparator to generate the clock from the mains frequency and 6 CD4511 each connected to 6 common-anode 7 segment displays for HH:MM:SS.

My question is how to build the circuitry. I was thinking of using an 8 bit counter to count at 100 and when the output is 0110 0100 (100 deca) using AND/NAND gates to build a new clock which goes positive only at 100 deca. Next one CD4510 for every digit and make them reset at different values with AND/NAND gates again. This seems a bit cumbersome. Is it an easier way to hook the counters up?


texts: The effects of back-EMF to the output voltage from the DC-converters?

texts:
simulate this circuit – Schematic created using CircuitLab

From the basic buck-converter circuit, is V1(backEMF) opposing Vout like so: Vo - V1 = Vr(voltage at load)?

Likewise for the case of a boost-converter?

simulate this circuit


texts: Single supply analog gate current mode switching

texts:
I need to switch a bunch of analog signals, in the \$\pm10\$ volt range, with the control coming from a microcontroller. Since the signals are all ending up in the virtual ground node of an opamp, I'm using current mode switching, as that allows using an analog gate with a much smaller signal range than otherwise necessary. Putting an example of that into schematic form, where we're switching the gain of an opamp stage:

simulate this circuit – Schematic created using CircuitLab

In this circuit, SW1 determines whether the input resistor is \$100k\Omega\$ or \$1.5k\Omega \parallel 100k\Omega \$. Note that since the switch is connected  either to the virtual or the actual ground, voltage over the switch is always \$\frac{\mathrm{Vin}R_{on}}{R_2}\$, which is quite small.

So my question is: what happens if SW1 is an analog switch with a single supply voltage? For example, the TS3A5018. Looking at fig 1 of the datasheet, at least the on-resistance even at zero voltage is just a few ohms, and unless it rises essentially discontinously, the switch terminals shouldn't be more than \$100\$mV below ground. On the other hand, this is out of spec, and also the datasheet doesn't really give any data hinting at what \$R_{off}\$ is when the input is slightly negative.

The reason I'd want to do this is that single supply analog switches are more plentiful, available in a wider variety of packages, often cheaper for similar performance, and I've got a 3.3V analog rail anyway. With a normal \$\pm6\$V or so 4053 or similar, I'd have to generate the analog switch power rails separately from the main \$\pm 12\$V supplies.

The question: am I right in thinking that this is not going to work? If so, how does this fail to work? Is there any way around having to throw in two more regulators or using an expensive \$\pm12\$V analog switch?


texts: How do I get the msp430 EZ430-RF2500 to communicate with an MPU-6000 gyroscope over SPI?

texts:
What are the steps necessary to get

Device 1. MSP430 ez430-rf2500 to communicate over Serial Peripheral Interface (SPI) with

Device 2. MSP430 5528 and MPU 6000 gyroscope?

Goal to get Device #2 to send inertial position data over SPI to Device #1. Device #1 will analyze received position data and send a control signal over SPI back to Device #2(attempting to achieve a stable hover).  As the position of Device #2 changes this process repeats.

I have come up with an outline of what I think is the right answer to solve a problem like this, however I was hoping the community can help with modifying incorrect/inaccurate information, adding useful information, or removing unnecessary information from my outline.

I have included 3 figures below that I will refer to in my outline:

Figure #0 (F0) - Device #2 MSP 430 F5528 Processor which is on connected to Inertial Sensor (Figure #1)

Figure #1 (F1) - Device #2 Inertial Sensor Schematic containing MPU-6000 Gyro chip

Figure #2 (F2) - pg. 47 on page Device #1 ez430-rf2500 SPI Configuration

Outline

Figure out which (Device #1 or Device #2) is "Master" or"Slave".
1.1 The master is considered to be the microcontroller that initiates communication. Since the Device #2 - Inertial Sensor (Figure 1) is the one that generates position data Device #2 should be the master.

1.2 The slave is considered to be the microcontroller that responds to initial communication.  Since Device #1 ez430-rf2500 will need to figure out how to stabilize Device #2 shown in Figure 1 and send it a control signal Device #1 should be the slave.
Figure out where to store and how to send position data on the Device #2 Inertial Sensor

2.1 Determine where the output buffer that will store position data is located on Device #2 (perhaps somewhere in Figure # 0)

2.2 Determine how to initiate transfer of output buffer data to Device #1 over SPI from Device #2
Write code to receive position data over SPI from Device #2 on Device #1

3.1 Determine where the input buffer is located on Device #1 that will store incoming position data.

3.2 Determine how to copy input buffer into registers on Device #1
Write code Device #1 will execute to generate a control message to be sent to Device #2
Copy control data into Device #1's output buffer and send it to Device #2's Processor (Figure #0)

5.1 Determine where the output buffer is located on the Device #1

5.2 Determine how to send control data from Device #1's output buffer over SPI to Device #2's input buffer.
Determine how to copy control signal from Device #2's input buffer and send it from Device #2's processor to Device #2's motor/servos to execute (i.e. creating a new position and triggering a repeat of steps 1-6 above)


texts:
I'm trying to drive a solenoid with an arduino pro. I've assembled the typical MOSFET approach with a protection rectifier:

The circuit works, and the solenoid is triggered, but very weakly. In other words: it moves, but as soon as I attach what I want it to  move, it doesn't have enough force to move it anymore. It works perfectly fine if I connect it straight to 12V, though. What might I be doing wrong?

The MOSFET is a BUZ91A.

The Solenoid is a 12 V ZYE1-0530Z (there seems to be 12V and 24V versions with the same part number). I couldn't find any specs regarding the impedance of this things, but I've measured 5 of them and they were all between 10.5 and 11 Ohms.

R2 is 2Mohm, no complaints there.

D1 is an 1N4001

I've tried increasing the voltage up to 16V and it gets better, but still weaker than directly supplying 12V from my PSU.

I suspect I'm not providing enough current, probably related to picking the wrong MOSFET?

I've tried a similar approach but using a TIP122 darlington array pretty much with the same results.


texts: Effect of oxidation on solar cell bus-bars

texts: Does oxidation of bus-bars have a major effect on the performance of the solar cells? I've been trying to find some answers but no outcome yet.


texts: Is there a protocol like SPI that supports multiple MISO and MOSI channels?

texts: I need to implement a driver that uses clock-data protocol within the data link layer. It's just like SPI but with multiple MOSI and MISO channels. Is there any pre-defined protocol like that? (DMA will be used if there is no such pre-defined protocol)


texts: Cascaded Transfer Function Method for Frequency Response

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Multiplying the transfer functions of multiple cascaded circuit fragments to get the frequency response of the system doesn’t work because of loading between stages. However, I came across the following equation from here:

On page 7-14 it says that you can do this if you introduce load factors into the equation:

Say I break up their simple example circuit into three sections and use their method as follows:

However, the transfer function I get is different than the transfer function I get with simple circuit analysis of the entire combined circuit using the following:

Plotting the responses in Matlab they are similar, but not identical, and the transfer function in the second case is much simpler compared to the first.  Is there something wrong with my calculations? Or can someone verify if/when this method works?

I used the above 2 methods and compared them to a more complex circuit built on a breadboard, the second method bode plot is very close to measured, but the cascaded transfer function method is way off.


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To my knowledge, a voltage source just drive all free electrons of a conductor  in a closed circuit to complete a loop (after reaching positive end.. Again to the negative end  ... To repeat the cycle) Is that correct or wrong??
    Moreover electric current is the quantity of charge passing through a cross sectional area per unit time..
   I mean if current increases, how come the electrons quantity increase in a closed circuit conductor....
  Correct me if I was wrong....
Thanks in advance


texts: Patterns for using watchdog and ultra low-power constraints

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I am designing a power-constrained device that has to gather some data, run from a battery for a couple of years and send data periodically. I want to ensure high reliability, because the device will not be easily accessible.

The MCU is an EFM32. Most of the time all sensing is handled by hardware peripherals. RAM is retained. RTC is running and periodically waking the CPU (let's say once every 24h).

I can turn the watchdog on when the CPU is woken up. Maximum watchdog period is around 250 seconds, which is much shorter than my sleep time. I know that it may save the day if the application hangs while CPU is active, but are there any design patterns that improve reliability when the CPU is sleeping? I don't have power budget for another chip or a second MCU.


texts: Problem in Z-Axis motion acceleration with MPU6050

texts: I extracted motion acceleration with MPU6050 and removed gravity. Now, the problem is when I put the sensor in no-move status, I read nearly zero acceleration in z-axis but when I turn it 180 degree and then put it in the rest it shows nearly -2. There is a constant of 2 and I don't know how to remove it. I want the sensor to show me a zero acceleration when it is not moving.


texts: Routing audio signal with CMOS Analog Multiplexer

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I am quite new to electronics but I'm planning to build a device for routing analog audio inputs (cinch) to one output. I want to select one input channel (using a raspberry pi) to forward to the output channel.
After a lot of reading about the basics, I found an analog multiplexer (the DG409) that seems to be able to solve this.

My question is, can I just solder the left and right cinch channels to the S1a and S1b (and so on) and wire the grounds together or is there anything else I need to do?

Edit:

As @pjc50 pointed out, I also need to supply suitable V+ and V- for the device. Looking at the available pins of the raspberry pi, I can find a suitable +5V supply but no -V. The data sheet of the DG409 say that it can be operated in either single or dual supply. To run it with single supply, do I have to connect V- to the GND or leave it unconnected?

And @nick-johnson commented that my signal needs to stay between the positive and negative rails. My signals all come from line-out jacks and should have only minimal current according to wikipedia:

  Line outputs are intended to drive a load impedance of 10,000 ohms; with only a few volts, this requires only minimal current.

So that shouldn't be a problem, right?