texts: Help Identifying a CMOS optical mouse sensor?

texts:
I'm working to repurpose the trackball assembly of a Logitech Trackman wired mouse for use in an experimental rig. I assumed that Logitech would use Avago's ADNS series of optical flow sensors, but it doesn't appear that way. I've managed to carefully disassemble down to the sensor, but still can't find a part number. One side of the chip reads "M8aSN" but this returned nothing from Google. The sensor assembly had 6 leads running to a PIC, while the sensor itself has four pins.

I'm hoping that some sleuths here might have some ideas. Thanks in advance.

Logitech mouse specs:
https://support.logitech.com/en_us/product/trackman-marble/specs

Avago ADNS series sensors (seemingly not what I'm looking at due to the difference in pin-out) [PDF!]:
http://media.digikey.com/PDF/Data%20Sheets/Avago%20PDFs/ToolKitSelectionGuide.pdf

Lastly, here is the most similar-looking component I've been able to find so far. It has four pins though it is surface-mount:
https://www.vishay.com/ppg?84286

Photos of what I've got:

chip-side:

mysterious "M8aSN":

full assembly of LEDs, chip, components-- this has 6 leads


texts:
I've been trying to figure out the various logic gates and am currently looking at a NOR gate as in the picture above. After reading various sites, I still don't get how this works as far is the output is concerned.

Based on this picture and what I know, A and B being what they are in the pic... A goes through the pMOS which gives an 1 since A is 0, and B goes through another pMOS which gives a  0 since B is 1... so you've got a 1 and a 0 going to the out put from that side, then on the other the nMOSs just take A and B and give what they are, so you have another 1 and 0 going to the out put from that end... What I don't see is how that translates to 0 for the output. I understand the meaning of NOR, that it's only true, 1, if both A and B are zero but I don't understand what's going on has far as the results of each input going through the MOSFETs to the output.


texts: Making a PMOS act as a low voltage drop diode

texts:
I would hope to replace my Schottky diode that is acting as a as or diode. I do not like how high voltage drop the Schottky diode is making thus I would like to switch to a MOSFET. And the simplest circuit I could with a MOSFET kind of like this. I do not know if this MOSFET will work

Correct me if I’m wrong on these points which I think is correct.
The MOSFET I have chosen will have a voltage drop of 0.01 V assuming I have a current of 250 mA (the expected current of the load).
With the circuit I have protected both my inputs from reverse voltage inputs. When both inputs are present the higher voltage input cannot go back through the other input.
Is my circuit sufficient? Would there be complimentary components needed?


texts:
In the following circuit, in order to obtain negative feedback, shouldn't we need A2 to be positive?
Also, is the correct feedback topology current-current?


texts: Prevent Raspbebrry Pi reboot from brief voltage interrupt using capacitors

texts:
My goal is to power a Raspberry Pi Zero W using an IP5306 charging IC which would receive its power input from a 3.7v 18650. The Raspberry Pi Zero requires 5V and can draw as much as 120mA without HDMI running.
The IP5306 should be able to power the raspberry pi from its battery source in theory. The issue I am running into is the following scenario...
The Raspberry Pi Zero W is currently on and is being powered by the IP5306 Charging IC. The 18650 is running out of juice so it is now time to charge the battery using an external 5V power supply. As soon as the external 5V is applied to the IP5306 to charge the 18650, there is a VERY brief interrupt in the voltage output of the IP5306. This interrupt is brief enough where you wouldn't even see an LED flicker but it is long enough to cause a Raspberry Pi and even an MCU to reboot.
This brief voltage output interrupt is a trait of the IP5306 itself.
I would like to know what I can do to prevent the Raspberry Pi Zero W from losing power when the external 5V is applied to the IP5306.
Would I need to add a shottkey diode with some ceramic capacitors in parallel between the IP5306 and the Pi?
If so, how many capacitors and what would their values have to be.
I don't know the exact duration of the output interrupt in ms.


texts:
Using LinkSwitch AC-DC converter as shown.

Output voltage is 12V, 120mA.

Converting 12V to 5V using a regulator will dissipate a lot of power as heat.

Is there any way to adjust the component  values to get 5V output?

Datasheet of Linkswitch


texts: Why did my transformer explode? Was it faulty?

texts:
I purchased a dual-voltage step-down transformer. It had 3 input leads for either 115V or 230V and could output either 12V or 24V on the center-tapped secondary. I taped off one of the input hot wires and connected the other two to a wall plug. I then connected the three outputs to a screw terminal so I could safely test them with my meter, but they were otherwise unconnected.
I went to plug the transformer in (to 120V) and it buzzed loudly for a second and then violently exploded with wisps of some pleasant-smelling magic smoke. On the primary side I could see that it had spewed some copper from the primary winding onto the insulation of the wires (I could scrape it off to see insulation below, so the hot/neutral wires weren't shorted because of cracked insulation). The transformer was hot to the touch even after sitting unplugged for a few minutes. Testing the resistance of the primary now I get an open circuit between one hot and neutral and about 1 Ohm between the other hot and neutral.
Why did my transformer blow up? The first thing I thought of is that it was defective and the primary winding was shorted somewhere. Is there something else that I'm missing? Did I need to connect the primaries in parallel? The wiring diagram on the datasheet is very simplistic but doesn't seem to indicate such - it quite literally has 3 lines coming from the primary side that say 0V, 115V, and 230V.


texts: State diagram for 2-bit parity generator

texts:
So the question I need help with is: Design a minimal moore state machine for a 2-bit parity generator that outputs ‘1’ if the number of 1s in a 2-bit sequence is odd, and outputs ‘0’ otherwise. Overlap is allowed. (Hint: this can be done with 4 states.)

Sample input: 0 1 0 0 1 1 0
    output: 0 0 1 1 0 1 0 1

a) Describe the states.
b) Draw a state diagram.

I've covered three pages trying to figure out how to draw the state diagram and I can't seem to get it to work. A 1-bit parity generator seems easy, but for some reason I can't figure it out for 2 bits. Any help is greatly appreciated.


texts: Cross Sectional Area of 132kV cable carrying 109A

texts:
How to calculate the cross sectional area for 132kV cable which have 109.35A?
What formula we must use?


texts: I've attached a picture from a data sheet(RN42 Bluetooth module) that I've been looking at. The amount of current specified for transmit is 45mA, is this per a packet of data sent ? So to send 1 Mbyte of data it would draw 45A !?!?! Sounds stupid but what is the 45mA relational too?


texts: Tactile switches to meet EMC standards and IP67

texts:
I'm designing a handheld device that has just a few buttons that will make some configuration changes. (Very much like a game controller) I'm currently making a set of 3 prototypes - a production run if any will be less than 25 units.

I want to use a SMT tactile switch on a small pcb and a switch cap that I'll have made (machined out of Delrin or 3D printed). The enclosure (plastic or a thin aluminum sheet) will have holes for the switch caps.

Why type of membrane should I used to make the enclosure watertight (to IP67)?

How do I shield for EMC?


texts: Very curious to know the range of 50 W transmitter of UHF range in nautical miles? The antenna used is 1/4 wave antenna of Jaybeam company. Can someone tell the exact formulation to find out the answer? Just to add further, height of Tx and Rx antenna is around 60 meters.


texts:
Is it safe to connect any 5V I2C slave device to 3.3V host?

I know, that DS1307 realtime clock can be connected to Raspberry Pi (3.3V IO), because DS1307 just pulls down data lines and 5V voltage never "comes out" from DS1307 SDA and SCL pins.

When I'm connecting pullups to 3.3V - it's not a problem for DS1307.

But what about other I2C devices, like MCP3421 ADC or ADT7420 temperature sensor for example?


texts: Routing the main power supply across a PCB and choosing vias for it

texts:
I have a board that uses several different switching converters with 33uH ferrite beads that take up a fair amount of space. I'd originally intended to keep them all at the top of the board (not top layer, top from a bird's eye view) and keep the 12V main power supply rail isolated near the edge of the board. However, I can cut down on about 25% of the board size if I move one of switching regulators to the bottom of the board where there's more space. In order to do this I have to route the 12V rail to another layer of the board. I'm using a 4 layer board where the top layer is a signal plane, the 2nd layer is a ground plane, the 3rd is a power plane and the 4th is mixed signal/ground plane (about 3/4 ground). I was going to route the 12V trace on the power plane. That trace would have unbroken ground planes above and below it. Additionally, the 12V rail is filtered by a ferrite bead pi filter the moment it enters the board. However, it would go beneath a noise-sensitive ADC on the top layer. Is there any danger to this?

The other part of my question relates to via selection. I'm intending to use one larger-sized via (calculated using the Saturn PCB toolkit) with an identically-sized adjacent via for the return path. I could use several smaller vias instead, which, for the same current carrying capacity, should have lower inductance and capacitance, but I don't see why this should matter for a DC supply rail.

Am I missing anything big here? I don't see why this should cause any problems, but I'd like to avoid any surprises...


texts: Systematic ways to design a finite automaton whose input-output function or relation is a given one?

texts:
Given a function or relation, are there some systematic ways to design a finite automaton whose input-output function or relation is the given function or relation, assuming there is at least one such finite automaton?
If I am not mistaken, this is used a lot for designing Moore or Mealy machines in digital design.
Thanks.


texts: Will relays work to build a physical ethernet "killswitch"

texts:
In order to incorporate a networked device into an automated test framework, I am looking at building a small number of ethernet "killswitch" boards that will simulate physically disconnecting the device.
In order to keep things simple and cheap, I'm hoping to use either a single or pair of relays to switch one core of one of both of the ethernet pairs. Normally the entire board will be unpowered. Application of a 5V signal will switch the relays(s) to the NO position and break the connection.
My questions are:

Are the relays in their NC state likely to interfere with normal ethernet signals?
This question suggests the answer is yes, but I'm wondering if there are particular things I should be aware of.

Will breaking one ethernet pair be sufficient to "disconnect" the device, or do I need to switch both?

I'm a competent electronic engineer, but I don't really know anything about the details of ethernet. This is 100Mbps ethernet (not gigabit).


texts: Measure capacitance in softwire using Tina/Multisim/other simulators

texts:
Is there a way to measure capacitance of a capacitive network as shown below in Tina-TI, Multisim, or other simulators? I tried searching but I couldn't find any way to measure capacitance directly as compared to the DMM in the simulators. Our professor requires Tina-TI, but if it isn't possible, we'll just ask his permission if our group could use other simulators.

We are only limited to DC sources since it is the scope of our course. We also considered using frequency generator or oscilloscope but our professor did not allow us.


texts: Why does one of my HiFi speakers only start working after several minutes?

texts:
not sure if this is an EE question, it's the closest SE site I could see?

I have a Sony separates mini-system (HCD-SD1) I was given; it's quite old now but good. Except that for a while now, when I turn it on sound only comes through one speaker. After a few (~5) minutes the other speaker will kick in. Sometimes, whacking the volume right up to MAX seems to also remedy it but I prefer not to for obvious reasons.

It only happens when turning the device on and seems to be worse in colder weather so I think of it as the device "warming up" even though it's clearly solid state!

I already checked the cables aren't dodgy by swapping the speakers round - it's the same output that has the issue not the same speaker.

What could be the cause and is it something I might reasonably fix, or have fixed by someone more competent, without large expense? eBay suggests $50 (£30) or so would get me a replacement 2nd-hand unit.


texts: Is there any physical limitation to cell carries sharing the same frequency?

texts:
Currently in the U.S. certain companies are granted leases on certain frequencies for cell phone communication. I was discussing with a friend how this allows a company with a lower frequency to get a physical advantage over another cell service company that may only have the option to lease a higher frequency. (For building penetration and distance of transmission)

Ignoring the engineering problem of revamping their systems, are there any physical limitation to opening up the leases and allowing all the major carriers to operate on the same band/frequency?


texts: differential ADC with a potentiometer in the positive input and grounded negative input

texts:
i have a problem in reading values from ads1672(datasheet). i setup this circuit:

the Reference voltage is +3.V (REF5030-TI page)

when potentiometer is @ +1.6V (i measured this by multi-meter) this out +2.9V!!
and when potentiometer is @ +1.4 the ads1672 output is -2.9V!!
 and when potentiometer is beyond +3v ads1672 output is almost +0V also when potentiometer is zero ads1672 ouput is -0V!!

Why!! any body have any idea?

Firsts Question: are this setup (with a potentiometer in the positive input and grounded negative input)  is good for test and setting up a differential ADC??

Second Question: what is VCM role in my circuit? (with respect to Refrence Voltage=3.v)

i think (ReferenceVoltage/2 =1.5) is center of input ads1672. is it right. but why??

Thanks All


texts: Voltage Gain for Driver in Class AB Amplifier

texts:
Can anyone tell me how to calculate the Voltage gain for Q3 in the following schematic ?

Is it the same method (or partially modified) like the one used for Class A amplifiers for Voltage gain calculation?
Av = R1/R2 ?


texts: Rotary potentiometer angle to voltage relation

texts:
I have a 10k rotary potentiometer which turns from 0° to 270°. I wire it to an Arduino with the middle pin (2) connected to an analog input (A0) and the other two pins (1 and 3) connected to 5V and GND.

simulate this circuit – Schematic created using CircuitLab

I know the potentiometer is a voltage divider between pin 1, 2 and 3 as above so as expected I get 5 volts on pin 2 when the potentiometer is turned left (0°), 0 volts when the potentiometer is turned right (270°) and something in between in the middle. The problem comes when I try to calculate the angle - voltage function. I expected that it would be a linear function that can be calculated from the two given points (0°, 5V) and (270°, 0V) but when I turn the potentiometer to 135° which is supposed to be the middle point I don't get 2.5 volts instead I get something around 1.5 volts. I also noticed that when close to 270° a single ° in rotation corresponds to a bigger voltage change than when closer to 0°. So is this normal or is my potentiometer busted? And if it is normal why is it so?

EDIT

I did some measurements and came up with the table below as Umar suggested

Degrees   |  Ohms  |   Delta
   0°     |    3   |     -
   45°    |   480  |    480
   90°    |   972  |    492
  135°    |  1704  |    732
  180°    |  3423  |   1719
  225°    |  7280  |   3857
  270°    | 10300  |   3020

So Kevin White is correct it seems that I have a tapered audio potentiometer and the function is logarithmic (the blue curve in Kevin's answer). Thanks, everybody for your time and effort.


texts: Interference from well pump pressure switch and microcontroller

texts:
I am using the Parallax Propeller to start and stop timers for an auto racing timing system. Out of 250 cars there were timing issues with about 10 or so. It was very random and hard to diagnose. I knew that somehow the input pins were somehow reading high and causing timers to start and stop. I also knew that it was very quick because one chip polling via a loop didn’t show the pin was high and another chip polling at 12.5ns detected it. After creating a pin test program and using a scope I found the problem. When switching on, a well pump pressure switch caused the pin to read high. It wasn’t every time either. (Although the scope was showing the interference every time). The pump was cutting on and off about every 5 minutes. About 75% of the time when the relay clicked on it caused the pin to read high. The scope was showing upwards of 2.4 volts. This is enough to make the pin read high. I am not switching the relay via the microcontroller. The relay is in a separate room in the building but still causing interference into my timing system.

I’m very inexperienced but I have a good knowledge of electronics. This high voltage stuff (the pump is powered with 220VAC) is not my thing though. The power supply for the microcontroller is connected in the same electrical panel as the well pump. I have tried using a 12 volt battery instead. No success. I have tried using capacitors on the power supply without success either. When checking the pressure switch I found that the 220 ground wasn’t connected. After connecting the ground it seemed as if it helped, but it still showed reading high about one time in 40 minutes with the well pump switching on and off about every 5. So I think connecting the ground helped but didn’t solve the problem.

Like I said I’m inexperienced, and don’t really know where to start. I have thought about taking a start capacitor off of a 220 air compressor and putting that on the load on the pressure switch. Would this help? Any other ideas on how to fix this problem?


texts:
I am explaining my question in detail now as I am realizing that I did not explain my question well.

I am a beginner in Verilog. To learn the language I am writing some sample applications.
At present I am writing Verilog code to convert 8 bit BMP image to half tone BMP image using Floyd-Steinberg algorithm.
Basically I am converting  8 bit pixels into 1 bit using the said algorithm.

I found the sample code for this algorithm in the book Advanced Digital Design with the Verilog HDL - Michael D. Ciletti on page number 555. I have successfully simulated the design in ModelSim.

The problem is the example is given for an image of size 6 x 8, but to learn and practice I am trying to convert this code for different formats and sizes. As a first goal I am trying to modify this code (which I have already understood well) to work for images of size 1000 x 1000. Since the example was for only 48 pixels (6 x 8), it was easier to write the instructions inside the module manually, as shown in the code given below.  But in case I have 10,00000 pixels (1000 x 1000) how do I change the code.
I cannot write such equations:

  PPDU a0(err_1,htpv_1[1],8'b00,8'b00,8'b00,8'b00,pixel_1);

10,00000 manually (kindly see the code given below).

I guess there has to be some way for automating this job.

In C I can use for loops for autoamting many things. But being a novice in Verilog I am unable to proceed. I will really aprecaite if somebody can point me to a useful link.

// pixel processor datapath unit//
module PPDU(err_0,htpv,err_1,err_2,err_3,err_4,pv);
output [7:0]err_0;
output htpv;
input [7:0]err_1,err_2,err_3,err_4,pv;
wire [9:0]cpv,cpv_round,e_av;
parameter w1=2,w2=8,w3=4,w4=2;
parameter threshold =128;
assign e_av=(w1*err_1+w2*err_2+w3*err_3+w4*err_4)>>4;
assign cpv=pv+e_av;
assign cpv_round=(cpv<threshold)?0:255;
assign htpv=(cpv_round==0)?0:1;
assign err_0=cpv-cpv_round;
endmodule

module image_converter (pixel_1,pixel_2,pixel_3,pixel_4,pixel_5,pixel_6,pixel_7,pixel_8,pixel_9,
   pixel_10,pixel_11,pixel_12,pixel_13,pixel_14,pixel_15,pixel_16,pixel_17,
   pixel_18,pixel_19,pixel_20,pixel_21,pixel_22,pixel_23,pixel_24,pixel_25,
   pixel_26,pixel_27,pixel_28,pixel_29,pixel_30,pixel_31,pixel_32,pixel_33,
   pixel_34,pixel_35,pixel_36,pixel_37,pixel_38,pixel_39,pixel_40,pixel_41,
   pixel_42,pixel_43,pixel_44,pixel_45,pixel_46,pixel_47,pixel_48,htpv_1,
      htpv_2,htpv_3,htpv_4,htpv_5,htpv_6
      );
 input [7:0]pixel_1,pixel_2,…..,pixel_47,pixel_48;
 output [1:8]htpv_1,htpv_2,htpv_3,htpv_4,htpv_5,htpv_6;
 wire [7:0]err_1,err_2,……., err_47,err_48;
 PPDU a0(err_1,htpv_1[1],8'b00,8'b00,8'b00,8'b00,pixel_1);
 ...
 PPDU a7(err_8,htpv_1[8],err_7,8'b00,8'b00,8'b00,pixel_8);
 PPDU b1(err_9,htpv_2[1],8'b00,8'b00,err_1,err_2,pixel_9);
 ...     PPDU b8(err_16,htpv_2[8],err_15,err_7,err_8,8'b00,pixel_16);
 PPDU c1(err_17,htpv_3[1],8'b00,8'b00,err_9,err_2,pixel_17);
 ….
 PPDU c8(err_24,htpv_3[8],err_23,err_15,err_16,8'b00,pixel_24);
 PPDU d1(err_25,htpv_4[1],8'b00,8'b00,err_17,err_18,pixel_25);
 ….
 PPDU d8(err_32,htpv_4[8],err_31,err_23,err_24,8'b00,pixel_32);
 PPDU e1(err_33,htpv_5[1],8'b00,8'b00,err_25,err_26,pixel_33);
 ….
 PPDU e8(err_40,htpv_5[8],err_39,err_31,err_32,8'b00,pixel_40);
 PPDU fi(err_41,htpv_6[1],8'b00,8'b00,err_33,err_34,pixel_41);
 ….
 PPDU f8(err_48,htpv_6[8],err_47,err_39,err_40,8'b00,pixel_40);
 end
 endmodule


texts: How do I capture past the visible area on the Rigol DS1054Z oscilloscope?

texts:
I'm using a Rigol scope in single-shot mode to capture a signal but it only captures the amount of signal that is visible on the screen. This results in a lot of zooming out to capture and zooming back in to view detail.
Is there a way to have single-shot just capture until the memory is full instead of until the screen is full?

For example when using serial decode the transaction you might want to capture is much longer than the zoomed in scale where you can actually see the decoding.

Is there a quick way to toggle between being zoomed out to capture, and zooming back in to the left hand side instead of the middle of the capture?


texts: Limit the current of a fixed voltage via MOSFET+PWM

texts:
I have a SMPS which I would like to current limit. The current limiter should have a negligible voltage drop when not limiting (say, <0.5%). I thought of inserting a MOSFET and a hall-effect current sensor in series, and switch the MOSFET on and off up to 20kHz to limit the current to a certain value when it is reaching that value. The output would be smoothed out by a capacitors.

Is it going to work? The SMPS is switching at about 50kHz, providing an adjustable voltage between 1.2V and 12V, and the current limit should be settable between 10mA and 5A.

What transistor should I choose for the job (what considerations etc.)?

simulate this circuit – Schematic created using CircuitLab


texts: Extending a switch mode power supply controller IC to work under higher input voltages

texts:
I have a AP6502 IC, which is a cheap DC-DC buck converter. It converts a DC voltage in the level of 4.7V-18V to a DC voltage of 0.925V-16V. I works under 2A current maximum.

Example Usage of AP6502 given in its datasheet.

But, I have a much higher DC voltage level; it goes up to 100V. The output voltage will be 18V. And I want to flow 20A current at maximum. I want to extend/improve the example circuit above, so that this IC would work under higher voltages.

My attempt on this is the circuit below:

Is it possible to do this kind of extension? If yes, would my circuit work, is my solution correct? If my circuit is wrong, what is the correct way of doing it?


texts: Why DC voltages in series do sum (or subtract, according to polarity)?

texts:
This is a newbie question.

It is clear that if you put two (or more) DC voltage sources in series like this:

simulate this circuit – Schematic created using CircuitLab

And you measure total voltage between A and D you get the sum of the two voltages.
I also realized that if you flip one of the sources, its voltage is to be subtracted from the total. So if I flip V1, I get a total voltage of 7,5 from A to D.

The point is, in short, is that I cannot understand why.

Voltage is the potential difference between two points.
As far as I have understood; when you take a single cell into account, that voltage is given by the fact that there is a difference in charge between one pole and the other of the cell.
So, when you close a circuit between A and B (or A and C whatsoever being nothing in the way from B and C), then electrical charge searching for its balance finds a way to, and it start flowing from one point to the other, according to the resistance it may encounter.
Same goes for Battery #2 of course, between C (or B) and D.

But when you put the batteries in series, what is going on between B and C if you close the circuit between A and D (with eventually any resistance in the middle)? Why is the overall potential difference increased (or decreased, according to the polarity?). How are electrons flowing between all the points? Why?


texts: Add a LiPo UPS without interfering with USB data

texts:
I have a device that accepts two power sources: 2 AAA batteries, and 5v via a micro-USB port. Because I loathe disposable batteries and I imagine plenty of other folks who have this device agree, I'd like to pop a LiPo battery and some kind of UPS circuit in line with the built in micro-USB port. The problem is, there's a maintenance mode function that uses that port and I'd still like to be able to access it. Am I going to get in trouble if I divert the power lines and leave the data lines intact? What can I do to improve this circuit?

Bonus question: The plastic molding for the female micro-USB port has a slack enough tolerance that it could fit a USB-C connector quite generously. I admit it's a bit silly but I'm tired of having a billion cables when one will do. Would there be any complications from swapping out the connector that I ought to be aware of? (USB-PD for the LiPo would be swell, but not really required)


texts: Which files are required to copy / version my Quartus project?

texts:
I created a 4-bit CPU in latest version of Quartus. Now I wonder which files are necessary if I want to put the files in source control? I understand that bdf, sof and qpf files should be versioned. Do I need to version the qsf, qwf and/or the files in /db ? The repository is github.com/montao/opencpu

$ tree
.
├── alu1bit.bdf
├── alu1bit.sof
├── alu4bit.bdf
├── alu4bit.sof
├── db
│   ├── system.db_info
│   └── system.sld_design_entry.sci
├── decoder2to4.bdf
├── decoder2to4.sof
├── fulladder.bdf
├── fulladder.sof
├── light.bdf
├── light.sof
├── mux4to1.bdf
├── mux4to1.sof
├── README.md
├── system.bdf
├── system.qpf
├── system.qsf
├── system.qws
└── system.sof

1 directory, 20 files


texts: How to test an atmega (arduino) i2c network

texts:
First of all sorry for my bad English and for this "theoretical" question on how is the best way to do things. I'm just out from university and no-one ever told me how problems can be resolved in a practical way.

I'm trying to develop a network of 4 atmega (I'm using Arduino platform), 1 master and 3 slaves. they are communicating via i2c.

I'm looking for a smart way to test it. right now my debug is happening via serial protocol: i have some

Serial.println(...);

and I'm reading them plugging the Arduinos via USB and reading serial incoming messages with serial monitor in Arduino IDE.

What i am doing now is:

Coding slaves having a test program (one for each slave) in the master (powered with a normal power supply).
When I'm "sure" that the slave is OK, unplug the USB of the slave, plug the master, coding the master.
Do this for each slave.
Pray.

This workflow has a lot of problems; it is a blind communication. When I'm working on the master, I don't really know what is happening on the slaves, and vice-versa. Then, if one Arduino crash causes the master to crash (because the I2C protocol does not provide for the fact that one slave does not respond or it is switched off) and I have to reset all slaves (I'm doing that by switching off the power supply of all slaves).

One more problem: Some slaves need real-time operation with stepper motors, and if a motor is running and some interrupts of I2C protocol library Wire.h occur (and this is happening each time the master require some message from the slave, I think), it eventually can happen while the motor is running and this cause the motors' movement (that must be as linear as possible) to be "trottered". To avoid this, I have only one-way communication: The slaves only receive commands. I don't know if this is the best solution but seems to work.

The blind one-way communication, the repeated plugging and unplugging of USB, plugging and unplugging the power supply and pressing reset buttons is making me feel stupid. Until now, I have done software development with IDE (Eclipse) that provides debug. If I have a some threads to be synchronized, I can have prints or whatever that make life simpler, and with software I'm doing unit testing that gives me a good tool for isolating the bug. Now with the Arduinos net, when something goes wrong, I don't have any idea how to find where is the problem. This is my first hardware network, and it is frustrating.

I need some advice on figure out a smart workflow, having a nice way to test my system, and to feel myself a coder.


texts: Can current flow in one circuit complete another circuit?

texts:
I have two circuits C1 and C2. The power supply for C1 is much lower-powered than the power supply for C2. How can I have C1 switch on C2?

I'm fairly new to circuitry, but I imagine I'm looking for a single component, whose name I cannot, for the life of me, figure out by Google.


texts: What is the role of the resistor at the input of the OpAmp?

texts:
Could anyone explain the role of resistor R1 in the circuit below?

Thank you.


texts: LTC5599: why are these baseband inputs passed through 49.9 ohms and the capacitor + SPI

texts:
I'm designing a radar transceiver board using the LTC5599. In the datasheet for the part, there is a schematic that shows the circuit configuration for the evaluation board. Here is an image of the layout given.

Here is a link to the datasheet:
https://www.analog.com/media/en/technical-documentation/data-sheets/5599f.pdf
Two questions:

For the SPI lines, why are there 1k resistors and 2.2pF capacitors? My best guess is that it is to reduce emissions, since the SPI bus can operate at a maximum 20 MHz and is likely to leak interfering signals. Is this correct? If so, should all SPI interfaces have the resistors and capacitors attached to them in a multidrop configuration?

Why are there 49.9 ohm resistors and a 100 nF capacitor to ground on the BBPI/BBPQ differential pair? For context, this pair of wires is the differential baseband input to the chip. The quoted baseband bandwidth for the chip is around 28 MHz. Are these resistors there for impedance matching purposes? And if I only plan on using baseband signals that are a few kilohertz in bandwidth, can I potentially ignore this part of the circuit?

Any help would be much appreciated.


texts: What is Subsampling in image processing?

texts: I was going through some image processing document. And I came cross this term "sub sampling". What does it mean? Is it sampling again already sampled data .. ?


texts: Switching high voltages with MOSFET at high frequencies

texts:
I need to rectify 220V 50Hz AC power to obtain 48V DC output voltage. Up to 40A current can be drawn from the DC side. 10% ripple is acceptable on the rectified voltage.

I am considering two different design options whose simplified circuit diagrams are drawn below.

simulate this circuit – Schematic created using CircuitLab

Option #1 is simpler. But the required transformer is freaking too expensive and huge. Also I need to use very bulky and expensive capacitors to achieve the desired ripple level.

Option #2 involves working at higher frequencies. It greatly reduces both size and price of the above mentioned components.

However, I can't make sure that the Option #2 would work as expected. Because I can't find any similar reference circuits anywhere, and I have never designed something like this before. Until now, I have switched high DC voltages by using both high side and low side MOSFETs several times. I have designed buck converters with up-to 40V input voltage running at as high as 2MHz frequency many times before. All of them worked as expected (if not any silly design mistakes were done). But this time, it is going to be both high voltage and high frequency and it is giving me the chills.

I need an experienced person to approve this (Option #2) design and give me some advice on it. I also need a suggestion on the switching frequency. How fast can I switch 310V DC voltage? Or, do you suggest a 3rd option?


texts: What does explain that the sum of voltage of the batteries connected in parallel is same?

texts:
Below is an explanation attached from my textbook:

It explained the batteries connected in series very well as seen. Honestly, I've been researching about batteries connected in parallel on my textbook. However, I couldn't see anything useful. Is there any chance that book didn't explain it? I'm out of my mind right now. What I mean is there should be something that explains what to do. Can you tell how to research or specify the reason?

My Kindest Regards!


texts: Choosing controller/processor when real time feedback control system is required

texts:
Currently, I am planning to work on a system, in which we will be gathering the data from the multiple sensor for more than 15 parameters,  based on the sensor value we will be controlling the actuators.

Some sensors  have higher priority than others, and the output from the sensor values should be displayed in the color LCD screen in real time.

When we have less sensor data I am comfortable using ARM Cortex-M4 based controllers, STM32 controllers from STMicroelectronics are my favourites. Now, as we are planning to have a feedback control system and the real-time display of the value of the sensor,  a real time operating system (RTOS) programming will be required. TouchGFX is a very good tool to display the value in the LCD display. I need your suggestion regarding which system should be selected for the above-mentioned project. (basic embedded, embedded with RTOS, embedded Linux, PLC, National Instruments controllers / LabVIEW etc, is there anything apart from what I have mentioned).

For a pneumatic based system, I have heard PLC based systems are very effective. Even Cortex-A based processors ( Linux based embedded systems) like Raspberry-Pi and Beaglebone can be used. If you could help in giving direction regarding which kind of system should be used for the above-mentioned application it would be great, and if there is any rule of thumb in selecting the one, please help with it.

I am curious about what kind of processors are used in standalone embedded devices such as ultrasonic machines and mechanical ventilators. How does an engineer program the touch screen, they must be using tools like QT?

If you have any knowledge regarding the industry-standard tool, please reply.


texts: How to protect Reset pin of MCU from ESD strikes?

texts:
We have been designing ESD protection circuits for MCU exposed pins. Here comes the reset pin protection:

The pin is connected with a ESD suppressor at the connector.
The pin is connected in serial with a 600Imp ferrite bead and is parallel with a 0.1uF capacitor.
The pin is pulled up with a 100kOhm resistor.

Here comes what happened when the reset pin is striked by ESD:

A. The system resets at 3.5kV contact.

B. The MCU is killed at 7.5kV contact.


texts: How many kilowatts (or amps) can I safely draw from the AC grid?

texts:
I rent a house in the SF Bay Area. The house is not exactly new, but it's in good condition; hopefully the AC installation is the same. Most AC outlets are without grounding; but fortunately, there are two outlets in the backyard that do have ground connectors.

I am thinking to build a kiln to fuse and slump glass. The problem is, these things draw a lot of power. I was told I may need 8 kW, perhaps more. Well, that's 72 A on a 110 V grid.

Is it safe to draw that much power from a regular outlet? If not, what other options do I have? Keep in mind, I rent this house, so I can't do any hacks.

The heating elements will probably be controlled via some nice hefty triacs (with an Arduino behind them, or something), which will open earlier or later during each AC cycle depending on how hot I want to make the kiln. Probably doesn't matter, but anyway, it's not a purely resistive load.


texts:
I'm thinking about a project similar to the home-automation systems etc...
Few problems came in the way,
The cost of the Arduino radio receivers/transmitters is huge, especially if I need few of them, cheap low qualities are available, although not reliable for long range.
my question is is it possible to make an AM / FM transmitter and receiver, connect them somehow to the Arduino, and make use of the received info?

making an FM transmitter etc... isn't that difficult but how to connect it to the Arduino and make the Arduino understand the incoming info?

any helpful infos are appreciated, thanks


texts: Need to build custom cable for Xilinx Programming

texts:
I need to build a cable that will connect 15 signals between two PCB boards. This will allow me to program a Xilinx FPGA over the select map interface (clock, data rw, cs).
Since these signals are all single ended and we have clock, I am concerned with signal integrity. In addition, one connector has Grounds while the other connector doesn't (actually going to span two connectors on the other side. I also do not have any termination on my clock. The clock rate will be in the MHz range. I was thinking of using a ribbon cable with modifications to do this. The connector without any grounds does have a couple of ground posts on the board I can attach to.
Both connectors are standard male .1" (.025 square post) connectors.
Any recommendations on how to connect this? I do have a block diagram as well.
Thanks!


texts: Using Lithium-ion Battery at -40 Celsius?

texts: Is it possible to use a 18650 cell Lithium-ion battery down to -40 Celsius, discharge only?  There would be no charging at this temperature (I've read that causes damage to the cell).  Curious if there is a rule-of-thumb for % capacity loss at this type of extreme temperature.  My current understanding that it will be specific to the electrolyte used by different manufacturers, but is there any potential for permanent damage or a complete freeze of the electrolyte preventing current flow?  I only see charts for some batteries down to -20 Celsius.


texts: dust sealed connectors for PCB to wire, and wire to wire

texts:
I am working on a solar car, and I have been going back and forth on what connectors to use to seal out the dust, and keep the wires together during extreme vibrations. I am looking for wire to board, and board to board connections. I have looked at the molex MX150L connections, but the durability does not seem to be high (only 25 cycles). Does anyone know of another product that would meet the specifications with a higher durability, and the ability to cary low level logic connections.

Thank you


texts: How can I accurately and precisely measure current in a 110V AC circuit, with a 1kohm-50kohm load, using an oscilloscope?

texts:
I need to measure the electrical resistance of a volume of ground.

To do this I need to cause a current to flow between two metal electrodes pushed into the soil (let's call them the "current" electrodes) and measure the potential difference created by this flow using a second set of electrodes connected to a voltmeter (lets call them the "voltage" electrodes).

Since the charge between the current electrodes causes ions in the soil-water to accumulate around the electrodes I need to use an alternating square-wave current source (in the 50-150Hz range - low enough so we don't get problems with complex impedance). And since I'm interested in the way in which the voltage between my measurement electrodes changes over time I will use an oscilloscope to make my measurements - which must therefore be voltages in a reasonable range (1mV to 10V).

The ratio of the current flowing between the injecting electrodes to the voltage between the measurement electrodes gives me a "resistance" value using Ohms law and a simple geometric modification. And that solves my original problem.

I can use an off-the-shelf 12vDC to 110V AC square-wave "mains" converter to supply the voltage to drive the square-wave alternating current powered by a simple 12v battery. 110v is high, I know, but the contact resistance of the electrodes with the soil is in the 1kohm to 50kohm range and to get a current flow high enough to measure with precision (at least 1mA) I need to drive the current with a voltage of tens to hundreds of volts - one commercial system I own uses voltages as high as 800v to measure ground resistance, though 100v maximum is more common.

The current will still be too low to measure precisely using a Hall-effect current sensor so I need an alternative.

So here's my problem: The off the shelf circuits I can buy to measure small current accurately and precisely, by conversion to a voltage of reasonable range, are DC only but the current flowing into the ground must be square-wave AC. So what simple circuit, perhaps a version of a shunt-plus-amplifier, can I use to convert the AC current to an equivalent (zero-crossing) AC voltage measurement in the <+/-10v range my oscilloscope can accept, without significantly affecting the current itself?


texts: Lightweight point to point communication protocols

texts:
I'm working on designing a point to point communications link for a cubesat.  I just want to confirm some of my understanding.

In my opinion it is only necessary to have physical layer and data link layer functionality.  Why would we need an IP address or a transport layer for a single point to point link?  But perhaps there is issues I am not aware of.  I understand that we need to be able to keep track of packets that arrive out of order, or don't arrive at all.  This is obviously an extremely challenging issue for a large network like the internet, but for a single point to point link, it seems reasonable to implement a simple packet reassembly scheme for ourselves.

Our mission is to monitor arctic sea ice using GNSS reflectometry data from GPS signals reflected off the surface of the earth.  The more data we can downlink, the better.  Hence, we are motivated to use protocols with as little overhead as possible.

Our transceiver is a microhard n290 transceiver, which has been flown on satellites in the past.  It is not compatible with existing amateur satellite stations, we had no intent to interface with these existing networks.  It provides FEC in hardware and a rate of up to 1.2Mbps uplink or downlink.

We know that we need a protocol that will expose a "packet interface" to us.  That is, we need a link layer protocol to packetize the serial data stream.

Since we don't have any kind of network, we don't need an IP layer.  As for a transport layer, we do need to be able to reassemble the data packets in the right order, and to ask for retransmissions.  Is it possible to put something like TCP directly on top of the link layer, and cut out IP?  This still seems like overkill to me though.  Our telemetry and status data will fit into a single packet.  As for the payload data, AFAICT all we need to do is break it up, label the data, and provide an order field.  Is there any reason not to do this ourselves?  It does not seem like a difficult task.  I've done it in Python using google protocol buffers - I'm able to serialize a file, shuffle the order, and then reassemble it.  I would need to put repeat requests on top of this, but everything else should be handled by the link layer.

I've been looking at the Saratoga protocol (http://saratoga.sourceforge.net/), but it is transport layer.  So, doesn't seem like a good choice.

Point to point protocol (https://en.wikipedia.org/wiki/Point-to-Point_Protocol) seems to be the most sensible way to go.  Right?  It is as lightweight as it gets.

Thanks for any guidance :)


texts:
Why MLCC capacitors have a different colors ranging from Brown to White?

I wonder if it is related to ceramic / dielectric type or maybe some manufacturing reasons? Maybe manufactures add pigment in purpose?

I have noticed that capacitors of the same parameters and type can have a different colors depending on supplier.


texts:
Continuing on with my power supply repairs. I hate it when I don't have a component and even with all of the junk parts I have I still have troubles finding things. So I want to buy some Schottky Diodes to have on hand. I am looking at

http://www.futurlec.com/DiodesGen.shtml#Shottky

They have some 1N58XX, BAT41-86, SBXXX, Along with lots of others.  My question is: can I just buy the higher voltage and current rated Schottky diode and sub them for the lower rated ones.  Is the main reason for getting the exact match the cost and ability to fit?  Do I only need to match package/voltage/current? Are Schottky and fast recovery the same?  Can I sub an ultra-fast for a fast recovery? And... at the moment I need a Schottky that is in the TO220 package.  Can I use two axial leads and just wire the cathodes together.  I know you can't do this for transistors but is the Schottky just two diodes in one package? Lots of questions and lots of thanks for any help with this.
Russ

PS: Are those good prices?


texts: Are Newfoundland's and Quebec's power grid synchronized

texts:
By the Maritime Link project (HVDC), which finished this year, Newfoundland is linked asynchronously to Nova Scotia, which is part of the Eastern Interconnection.

But is the power grid of Newfoundland and Labrador synchronized with the Hydro-Quebec network?


texts: Different design in relay load connections

texts:
(I know, relay are drawn in the wrong way, NO contacts should be in serie with load, I'll fix it ASAP)

When I have to build a board to switch many devices (mains powered), I always use a single "common rail" for all loads, like the one in this image:

But in the past few days I had to fix two fridge (two different brands) and I noticed that loads connected to the control board relays used a rather different schematic:

I wonder why they've used this type of connections. I add FWIW that there were no particularly heavy loads, and wires, relay and PCB traces were all correctly sized for the power needed, and moreover there were no analogies between "grouped" devices.

(I know, relay are drawn in the wrong way, NO contacts should be in serie with load, I'll fix it ASAP)


texts: zener diode protection on input of op amp?

texts: I saw a zener diode protection circuit on an Arduino analog pin, and it had a 1k ohm resistor in series.  I want to protect an op-amp, and I don't see why I need the 1k resistor, so the question is whether this circuit will work, protecting the input with a zener diode.  Note that the transistors controlling the gain are actually 2n7002 MOSFETs, the symbol is incorrect in the diagram because of an unrelated problem.


texts: Dangerous to store jump-starter power bank in car when outside temperatures peak at ~105°F?

texts:
I'm looking to buy a portable jump-starter power bank that's rated for up to 140°F.

I'm wondering how dangerous it would be to store it in the car (trunk or globebox) if I know outside temperatures might occasionally peak at ~105°F.
(Note this is outside air temperature. I don't know how hot inside a car can get.)

I know it can result in reduced lifetimes but I do not care about that. I just don't want there to be a risk of fire, is all.

It's 14000 mAh and the thought of a lithium battery fire scares me, but I can't imagine that it wasn't designed for this use case. Would this be dangerous or safe?

Bonus points if you could describe the safety mechanism(s) that are typically employed to protect against this. It may help me understand the risks better.


texts: How to design a Circuit that can turn a LED ON depending on the input voltage

texts:
I have three LEDs, and I want to turn the first LED ON if the input voltage is 4V , I want to turn the first and second LED ON if the input voltage is 8V and so on.

Is it possible to do without any microcontroller? I want just microeletronics devices working on it.


texts: Relating input torque on BLDC motor shaft with output current

texts:
I am trying to build a drone generator with a gasoline engine and a 14-pole,170KV, 2KW BLDC skateboard motor (this one). Before designing the system and running it, I wanted to clear out a fundamental doubt that has been troubling me. Details are as follows:

At a given voltage, how is the maximum output current that my generator can deliver related to the input torque at the generator shaft? Would increasing the input torque on the generator increase the current delivering capacity of my generator?

I am aware about the fact that at constant supply voltage (hence speed), a BLDC will draw different currents for different propellers due to difference in aerodynamic loading.

Also,in brushed permanent magnet dc motors, at a constant voltage, the motor will draw whatever current it needs from the source (with a little voltage drop) OR if I use a brushed dc generator, I will be able to generate larger currents (at the risk of burning my coils) at constant voltage (const. shaft speed).

Will the same hold true in case of a BLDC?

Please share your views.

Cheers.


texts:
I want to know if there is an approximate or exact way to know the consumption in watts of household appliances in a house from the monthly consumption that reaches the bill.

Taking into account that it arrives in kWh and I want to convert any value, which would be the best option.

305 kWh to W


texts:
I want to design a pulse transformer to drive a MOSFET.

Parameters are as follows:

Voltage = 15V
Current = 2A
Switching Frequency : 400kHz.
Ratio 1:1.
Duty Cycle = 50%

I know the following formulas, but I don't know their chronology for implementation.

V=Ldi/dt
L = N^2Acmu/lg
AcAw = L I I/KBmJ  [Area Product]
N = LI/BmAc
lg = N^2Acmu/L

This MOSFET driver will be general as I don't have any application in my mind for this yet.

1)  Please help to step by step finding each parameters and suitable core selection.

2) Is it necessary to have any application, while designing a pulse transformer?

3) Pulse transformer is not a transformer, but a coupled inductor. So design should be from inductor's perspective. Am I right?

4) Is there a way to select a ferrite core from wattage? Like this one would be 15 x 2 =30 Watts.


texts: Change waveform into binary in Saleae Logic Analyzer

texts: I'm using this famous logic analyzer and I would like to know if I can change the waveform into binary, like I've done in this pic (white numbers).


texts: I need an equation to calculate the time for a power percentage of a half cycle sine wave into a resistive load

texts:
I need to calculate the time a thyristor/triac needs to be on for a desired percentage of full power of each half cycle of the AC line input.

On for the full half cycle will give me 100%. On for 1/2 half the cycle will give me 50%. (sounds easy so far) But being on for 25% of the time does not give 25% of the power. And this is where I need someone with more brain cells than I still have. I have done some Google searching but have been unable to find the answer. Google doesn't understand what I really need.

Trying to think this through is stressing the remaining cells I have. And if I was confident I would get it right then it would be worth it. But I was never great at this kind of math even when I had cells to lose.

What I need is a an input variable, desired power percentage, and an output of the percentage of the half period of the sine wave.


texts:
I have been building many different variations of op-amp oscillators but have come across a recurring issue that has manifested itself again in this VCO schematic:

I find that when turning on my power supply I get waveform output for about half a second and then an instant cut off. I used a potentiometer as a voltage divider and it seems to work. (Turning the supply on and off again and listening to the pitch of the wave). I run the various circuits from a +/-12V supply with a third ground connection and have tried using TL072 and TL082 opamps but to no avail.

The Issue: When I build op-amp oscillator circuits (other than schmitt trigger oscillators which work perfectly every time) I find they need to be "jumpstarted" in order to start oscillating, I consistently encounter issues where turning the frequency too high permanently "turns the oscillator off", the oscillator slowly goes down in pitch only to stop outputting completely and the aforementioned issues.

The Question: Is there a common link/issue with op-amp circuits that cause these issues? When simulated, all the circuits output the correct waveform yet seem to be completely inoperable when actually built. Why does a schmitt trigger op-amp oscillator work perfectly every-time yet other don't? What do other oscillators (say a triangle/saw oscillator) rely on that a simple square wave relaxation oscillator does not?


texts: Transistor as Momentary Switch Wemos D1 Mini Reset

texts:
I am trying to create a water alarm based on the Wemos D1 Mini and an off the shelf water alarm. The basic premise I am trying to accomplish is when the sensor creates a circuit this then causes the D1 Mini to boot by triggering the reset. The D1 Mini would then be programmed to send me a notification and then go back to sleep as the alarm sounds. I want to trigger the reset button again once the sensor circuit breaks and the alarm stops. By doing this I hope to save drain on the 9V battery that the alarm uses.
I've tried something similar to this circuit here:
Can I convert a toggle switch to momentary switch using a transistor and capacitor?
Here is my schematic

I am getting intermittent results sometimes it works both ways with opening and closing the circuit and sometimes it only works when the circuit is just closed but no on the open state. Any guidance or suggestions would be greatly appreciated, thanks.


texts: Why do they hermetically seal(No screws - need to cut to open it) power supplies for common household electronics like phones,routers.. etc?


texts: Instructions on how to build electronic devices

texts:
I have got plenty of books in the theory of electronic devices, but I wish to build these transistors (BJT, MOSFETS, etc) and diodes by myself.

Which books are there in offer to learn how to do this?


texts:
What is the capacitance formula between two (2) evenly curved plates?

Imagine these plate halves curved around on opposite ends of a cylindrical dielectric material. Assume the curvature angle as 'theta' where 0 <= theta <=180 degrees. @theta=180 degrees, they become standard parallel plate capacitors whose formula is well known.


texts: General expression for non-unity gain feedback system's steady state error with disturbance

texts:
Thanks in advance for having a look.

I finally have some time on my hands to go back through my controls systems text and I want to understand how the general expression is derived; rather than just use the equation without understanding where it came from.

I'm hoping someone can help me find out why I have one extra term [1/G(S)] in the general equation which defines the steady state error of a non-unity gain feedback control system with an external disturbance.

I've searched the Internet and have found and read numerous papers about the topic (mostly from university lectures) but, none show the development of the general equation.  The papers usually show the general equation without any development, only how to use the formula, or the paper covers only the unity gain case.

I've uploaded images showing the steps I've taken during the derivation of the general equation along with the final result.

My work matches the equation in my control system's text except for the 1/G(S) term.

Thank you.

Ed


texts: Very old dual coaxial TV outlet, how to fix it to connect to a modern TV?

texts: i've recently moved into an older updated apartment building and want to connect to the TV outlet but have a connection that i've never seen before. Can someone point me in the right direction of how this connection operates and or new connectors compatible to fix?


texts: Can Cortex M4 data watchpoint trigger an interrupt without a debugger?

texts:
I am trying to diagnose memory corruption on a Cortex M4 (Kinetis K64). With the debugger (J-Link) attached I can set data watchpoints and the core will stop when a memory address is written.

I want to use this feature for field diagnostics. I set up my watchpoint like this:

uint32_t test_variable;
DWT->COMP1 = &test_variable;
DWT->MASK1 = 0; //match all comparator bits, don't ignore any
DWT->FUNCTION1 = (1 << 11)/*DATAVSIZE 1 - match whole word*/
           | (1 << 1) | (1 << 2)/*generate a watchpoint event on write*/;
test_variable = 5; // <<----- CPU stops after this line

With the debugger connected I get a breakpoint, the CPU simply stops. When the debugger is not connected nothing happens, the code just runs. I would expect a debug fault or a system reset (like with the BKPT instruction without a debugger).

Is it possible to configure the DWT (or perhaps ETM) to generate an interrupt or fault when a watchpoint is encountered without a debugger connected?


texts:
A KDE brushless DC motor has:

Kt = 0.0189 N*m/A (Kv = 505 rpm/V)
R = 7 mΩ
voltage range of about 30-60 VDC
Specsheet link

Assume the motor is

connected to 30 VDC input
ideal, sensored, six-step commutation speed controller
initially stationary (zero back-EMF)
perfectly cooled

Is the max torque of the motor equal to 81 N*m, or do I need a conversion factor for per-phase/line-to-line?

$$ T_{max} = k_{t}I_{max} = k_{t}\frac{V}{R}$$
$$ T_{max} = (0.0189 \frac{N \cdot m}{A}) \frac{30 V}{0.007 \Omega}$$
$$ T_{max} = 81 N\cdot m$$

I forgot to admit that the “max current” is outrageous to begin with. Without good cooling, the motor can melt at 10s of Amps, let alone 10s of thousands. I’m just curious if there are any other conversion factors needed for the torque calculation.


texts:
What does faraday’s equation for induction gives us ? Now my book says it’s just the induced emf and other times it’s the average induced emf and i’am confused.
For example , the book says that the average induced emf in a dynamo in a quarter cycle equals : -NBA*4f
And that is derived from the farday’s equation : emf=-N*(Rate of change in magnetic flux) ... and other times when using the same equation it’s jus the ‘induced emf’ .. what is the difference?


texts:
I'm currently stuck on the expression listed below. I applied almost all the Boolean algebra rules trying to figure it out, but no luck

Here is the expression:

AB'C*(BD+CDE)+AC'
Applying Distributive law:
AB'CBD + AB'CCDE + AC'
Applying A*A'=0 and C*C=C
AB'CDE+AC'
Factoring:
A*(B'CDE+C')
This is where I'm stuck. This is where I tried most of the rules and got nowhere

The books solution however is:

A*(C'+B'DE)

Then, I found this site and it also gave me a different solution. I don't know if the book has a wrong solution, or an alternate one

Boolean Algebra - Digital Electronics

Their solution was:

A * C'

Any suggestions? Thanks.


texts: Can I use lower gauge wire for short runs of longer high amp circuits?

texts:
This question is probably more of a "please explain whatever concept I'm missing." But I'll start with my specific question.

I'm building an electric brewery and am using a 5500W 240V (23A) heating element. I'm using 10 gauge wire for most of the circuit that services the element. I have a small section that I'm yet to design/build that is basically a mechanical relay that feeds a solid state relay. The mechanical relay (model: SLA-05VDC-SL-C) has very small leads, although it is rated for 30 amps. Connecting 10 gauge wire to this relay is fairly impractical.

It would be a lot easier to connect a short run of 18 gauge (could be only a few inches long). I expect this is a bad idea... is it?

If it isn't a bad idea, this rather confuses me... why then could I not get away with daisy-chaining dozens of short 18 gauge runs for the entire circuit?


texts:
I have an electrocardiogram sensing circuit that uses an INA321 amplifier for common mode rejection on two measurement electrodes. The device is meant for hand-to-hand measurement of the heart rate and powered by a low voltage.

If supplied by batteries, the circuit works well. However, the device is now connected to a small computer and screen for demonstration purposes. The switiching power supplies of such devices tend to couple about one half of the mains voltage into the common ground of the devices. I guess they use two equally large capacitors between ground and the two mains supply lines for some unknown purpose.
The INA321 can never reject 110V of course, in respect to the heart signal of about 1mV and having it powered with 3 to 5 volts.

Even if I connect the system ground to the mains protective earth, there is still a voltage up to 50V between mains protective earth and the body standing on the ground.

So is there any way to supply computer and screen without having them tied to some hefty earth capacitance?


texts: Amplifying current of the voltage divider

texts:
Perhaps it was asked a million of times, but I could not find the answer.

Say for example I have a basic voltage divider used as a reference for TL431 or a simple resistor in pairs with a zener diode. I can stepdown the voltage, but I can't exceed the current above some point, because of the upper-leg resistor. Am I right? I just can't workout an idea into my brains about whether or not I can amplify this current and still remain the same voltage even after doing some research. Could I do it using FETs? I want to supply 555  with 5V from mains input, but this part of the circuit will also be used to drive a pair of transistors, so I want to have an advantage of higher current.


texts: How to Find the Thermal Resistance Junction to Ambient

texts:
I have this BUK9M12-60E MOSFET.
I have calculated the maximum power dissipation of the MOSFET to be 14W (Conduction loss, Switching Loss and Gate Loss). I believe that I don't require any heatsink.
I'd like to calculate the the Junction temperature of the device when it is working and when my ambient temperature is 85degC.
But in order to find, I don't have the Thermal Resistance (Junction to Ambient value). So, how to proceed with the calculation to find the junction temperature.


texts:
When I put a piece of aluminum foil underneath an RFID card, the RFID reader is unable to read the card when it's placed in front of it like this (or around it):

The reader IS able to read the card when it is at this distance WITHOUT the aluminum foil underneath.

The only way I could get the reader to read the card with aluminum foil underneath was when I put the card directly below it like this:

What is going on to make it work this way?
Could it be the antenna's configuration on the RFID reader? The RFID card? or both?


texts: Why is this device power usage so much power and with such variation?

texts:
I just got a wattage meter to try to get a sense of where my electricity usage is going. One of the surprises was my cheap drugstore humidifier, which seems to be drawing 640 watts. I have a huge basement dehumidifier that's only using 240 watts and substantial power tools that use even less.

The other strange thing is that the humidifier power usage jumps around dramatically. I made an animated gif of the usage, but it's too big to paste inline, so here's a link:

https://www.dropbox.com/s/185m6o45ja6d6z7/humidifier-power.gif?raw=1

What it shows is the usage jumping constantly and widely, from 640W all the way down to 610W, just in a few seconds. It varies even more widely over longer observations.

So why is this little appliance using so much power and with such wild variation? Could it be defective, or even dangerous?


texts: Can you ruin an outlet by touching two wires together.

texts: Recently I was switching the power cord for my dryer and before I attached it to the dryer, I plugged it in to make sure it would fit.  The metals st the other end touched. They popped extremely loud and burnt me. Could I have just ruined my outlet?


texts:
Guys i have a circiut in below. There is a problem: i couldn't fix how to prevent this arc on my button. At 2. & 4. pins of button have 100nF and a resistor 1M to series these 2. and 4. pins. When i try to put 10K ohm paralel to 100nF operating of circuit is being broken. Cause that 100nF capacitor makes latch circuit stay low at power up. Here are my circuit schematic and photo of arc of button.
I have put 4M7 to make any impact but no matter.

[![enter image description here][2]][2]


texts:
From this discussion about Spice internals, it looks that Spice builds a matrix for a netlist. I wonder how it does it in detail, e.g. for  to write a simple parser.

E.g. :

R1  1  2  4
V1  2  1  2

How can a data structure of this circuit look like?


texts: I have an op-amp with a 100 MHz bandwidth. The input of this o-pamp will be a 65 MHz square wave. Can I expect to get something like a needle looking pulse? Because I am only going to have the first harmonic in it?


texts:
Assume I want to have a continous sine signal as input to my VHDL code. The values will be of type float since it will take on non-integer values for example: 10.5 mA.

How do I manage these numbers in my VHDL code?

I have tried to use: type Voltage_Level is range -5.5 to +5.5; as an example but it did not work since i couldn't import signed vector into Voltage_level since Voltage_level must be represented as a signal.

I would appreciate if someone could help with these kind of issues? What is the most easiest way to deal with this?

The basic problem is when I input non-integer values, say 10.5 and try to use the same value as input the FPGA outputs a rounded integer, in this case 10. So it seems that I can use VHDL only when i deal with integers and bit vectors, which is very limiting use scenario. Especially for people like me that work a lot with various kinds of signals.


texts:
I need to control a 5V 60mA load from an Arduino pin, but as the load has an output (tacho) that I will be reading from the Arduino, it seems I need to connect it as a high-side switch.  What would be the best way to do it? I guess I need a P-MOSFET but would I need another NPN or N-MOSFET to control it?

(I have searched but mainly found ways to connect higher voltages, 12V or so... Couldn't find anything related directly to controlling 5V high-side, or couldn't understand it... noob in electronics).

An schematic would be great.


texts: Why would a 74LS14 be used to enable another IC?

texts:
As a learning experience, I am studying a 64K 80 COLUMN expansion card for the Apple IIe.  The model number is 820-0067-D for those interested.

Anyway, I'm sure the schematic is online somewhere but I just wanted to do this for fun.

The first thing I noticed, however, is that it appears the designers used a Hex Schmitt Trigger Inverter (74LS14 PC) solely to enable another IC in the circuit (Octal Bus Transceiver SN74LS245N).

So on the 74LS14, they tied Y1 to !E on the 74LS245.  And, since the 74LS14 has A1 tied to Y3 and A3 isn't connected to anything, it seems to enable the 74LS245.

Why would they do this?  Why not just tie the 74LS245's !E enable pin to ground?

In fact, I can't see why the Schmitt Inverter is used at all.  The only other connections it has is A6 to external pin 26 on the motherboard and Y6 tied to A5 and Y5 tied to nothing.

It just seems like a waste.  Do you think it was used as some type of propagation delay?  If so, seems like it would only be around 50ns or so.

Here is a crude schematic that I came up with.  I might just try and dig up the real schematics to make sure I'm not crazy.  lol

simulate this circuit – Schematic created using CircuitLab

EDIT

Looks like I was wrong.  A3 does indeed connect to Y5.  Also, A2 is not floating, it is connected to GND.


texts: Replace CAN with SPI to communicate with two microcontrollers

texts:
I want to  replace the CAN with SPI to communicate with two microcontrollers within the same board.
The current solution is with CAN protocol:

uc1: at Init, it sends 1 message (msg1) to uc2. After that uc2 receives it and does some actions.

uc2: before shutdown, it sends 1 message (msg2) to uc1. After that uc1 receives it and does some actions.

My question:
Can I replace CAN with SPI to communicate with these two uCs? if yes, then should I implement both Slave and Master SPI drivers in both uCs?


texts:
I am new to neural networks and I am trying to implement self driving on an RC car. I was planning on using a CNN for image recognition (Correct me if I am wrong which I most likely am).

I was wondering if it was possible to run image recognition on a cheaper processor rather than a full single board computer.

P.S I found the following module, I was wondering if anyone has had any experience with it.

https://www.seeedstudio.com/Sipeed-MAIX-I-module-w-o-WiFi-1st-RISC-V-64-AI-Module-K210-inside-p-3210.html


texts:
I had a question that I was hoping someone could help with. I am building a cluster of raspberry pis to do research on and I decided the best way to power all the nodes was through micro usbs. (I figured if I did it through the 5v pins, then I would have to add fuse protection and design/implement a PCB board for 40 nodes - which will take quit a lot of time) I was in my lab and I found two left over power supply boxes from other projects. They are Thermaltake TR2 W0070 430W ATX12V v2.3 Power Supplies (here is a link to view the specs: http://www.newegg.com/Product/Product.aspx?Item=N82E16817153023). Is it possible to use this power supply to power the pis (using the micro usbs) or should I look for another option such as a 10 port AC adapter (e.g. like this one: http://www.meritline.com/10-ports-usb-20-hub-power-adapter-included-with-ac-adapter-white-with-silver---p-56107.aspx)? If it was possible, how would I do it?

Thank you very much for your help in advance, I really appreciate it!


texts: emi standards/best practices for PC cases

texts:
According to an EE friend, the FCC specifies EMI tolerances (max outputs) for PC components, including cases. However, here it says that there are standards for a number of components but not cases.

1) Am I understanding correctly that there are no requirements for cases?

2) According to the EE in question constructiong a PC case from anything but (mostly) metal will result in excessive EMI radiation for my purposes (audio) leading to stray signals. Furthermore he says that ventilation holes (number, diameter, and position) are calculated based on stray em wavelength. Is this the case?

3) If all of the above are the case, is there perhaps some lining I could apply to non-metallic enclosures to control stray EMI?

Many thanks in advance

Joe


texts: stm32f303 ADC continuous conversion mode multi-channel does not auto start new sequence

texts:
I am using a STM32F303v with 2 ADC regular channels in cotinuous mode with a DMA and would like continuous conversion to take place in order to enable a stream of data.

Base on the setup of my DMA and ADC below, I am unable to perform continuous conversion. On further debugging, I found that the very first conversion is successful and then the ADSTART bit is set back to 0. If I manually set ADSTART=1, the conversion starts, DMA does the transfer when it finishes and then ADSTART goes back to 0. Please help.

DMAy_x = DMA1_Channel1;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)dest;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_BufferSize = 2; // in data unit
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&ADCx->DR;
    DMA_Init(DMAy_x, &DMA_InitStructure);
    DMA_Cmd(DMAy_x, ENABLE);
    ADCx = ADC1;
    ADC_Cmd(ADCx, DISABLE);
    while(ADCx->CR & ADC_CR_ADEN);
    ADC_DeInit(ADCx);
    ADC_InitTypeDef ADC_InitStructure;
    ADC_StructInit(&ADC_InitStructure);
    ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
    ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
    ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
    ADC_InitStructure.ADC_NbrOfRegChannel = 2;
    ADC_InitStructure.ADC_ExternalTrigEventEdge = ADC_ExternalTrigEventEdge_None;
    ADC_InitStructure.ADC_ExternalTrigConvEvent = ADC_ExternalTrigConvEvent_0;
    ADC_InitStructure.ADC_OverrunMode = ENABLE;
    ADC_InitStructure.ADC_AutoInjMode = DISABLE;

    ADC_Init(ADCx, &ADC_InitStructure);

    // Set up ADC channels
    for (uint16_t i = 0; i < nPins; ++i)
    {
        // make them regular channels with rank i +1, sample time is 19 ADC cycles
        ADC_RegularChannelConfig(ADCx, PIN_MAP[pinNames[i]].adcChannel, i + 1, ADC_SAMPLE_TIME);
    }
    ADC_DMAConfig(ADCx, ADC_DMAMode_Circular);
    ADC_DMACmd(ADCx, ENABLE);
    // Enable everything
    ADC_Cmd(ADCx, ENABLE);
    while (!(ADC_GetFlagStatus(ADCx, ADC_FLAG_RDY)));
    ADC_StartConversion(ADCx);


texts:
I have a latch, and I could use some advice on starting the latch in a known state.

I'm running some robotics off of an ATX power supply, controlled by an Arduino.  The motors and such are weak and not particularly dangerous, but just the same I'd prefer to have an emergency shutoff function.  I intend to do that by sending PS_ON high permanently if an incoming signal I'm calling STOP ever goes high.  That is, I need a latch.  I want to include this latch circuit in a printed circuitboard that accepts power from the ATX and commands from the arduino. That way, over time, I can connect more sensors to the STOP signal as I build them and feel they're necessary -- big red button, limit switch, vibration, heat, anything I don't want.

The safety sensors will all be powered by 5V_STDBY.  The arduino will itself be powered by either 5V_STDBY or its USB connection (jumper select), and everything else will be powered on main +5/+12.  The arduino will have a pin to pull the ATX's PS_ON low and turn on main power.  If STOP ever goes high (or low), I want the latch to pull PS_ON high until the power supply is switched all the way off with the physical switch (5V_STDBY goes low).

My best guess is the following circuit:

The problem is that I'm not really sure how best to make sure the latch powers up with Q' low.  For example, I could try using an RC network to keep the reset pin high until a capacitor charges as soon as 5V_STDBY comes on, giving me a small amount of time with the reset pin high.  But here, I don't know how long it takes for 5V_STDBY to come on, and I want the reset pin to still be high once 5V_STDBY settles.  It seems like bad design to depend on the specifics of how long 5V_STDBY comes on, because I can't predict the behavior of decoupling capacitors, power loads, etc.  I could build a circuit to determine when 5V_STDBY has settled, but that sounds like a lot of unnecessary complexity.  I could use an RC network to keep the reset pin high for a small period of time after ARD_PS_ON goes high... which now that I think of it is not a bad idea.  But maybe there's something I'm missing.

Are there any considerations I should think about in having a reliable latch circuit?  If I use an RC network as an input to a latch, I'm gradually varying the input voltage.  Is that a problem?  Should I perhaps use Zener diodes to sharpen that drop?  Heaven forbid, an analog comparator?  Are there ICs I'm not aware of that deal with timing issues like these, and might make my life easier?

EDIT:

Pardon the timestamps; they're not accurate, and I don't know how to turn them off on the app I downloaded.  First, the user turns on the physical switch on the back of the ATX power supply, thus turning on 5V_STDBY but not main +5/+12.  ATX_PS_ON has a pullup resistor; as long as it's high, main power is off, so ATX_PS_ON goes high at this time.

I want the latch to power up with Q' high, so I want to bring RESET high briefly.   Since 5V_STDBY powers the latch, I want RESET to still be high once 5V_STDBY stabilizes so the latch gets a good start state, and to the best of my knowledge, I can't predict how long that will take because I don't know how 5V_STDBY is loaded (correct me if I'm wrong).

Sometime later, possibly many minutes, the microcontroller will bring ARD_PS_ON_PIN high to turn on main power for the rest of the robotics.  It will leave it there forever.

If subsequently the sensors detect a bad state, they will bring the STOP pin high, maybe only briefly.  This brings Q' low, ATX_PS_ON high, and turns off main power, until the power supply is power-cycled.

The main question is how to either get that behavior on the RESET line, or design my latch not to need it.  I feel that I must be making a hash of this: powering up latches and even gates in a known state is something every logic IC since the beginning of time has had to do, so there must be best practices.


texts: Different (15 and 10 pF) load capacitors on 32.768 Hz quartz crystal

texts:
I've got some random chinese electronic desktop clock/alarm.
It turned out that it's completely missing any capacitors on crystal. That was the reason why the clock were going faster ~5 min each month.
6 month ago I've soldered 15 pF capacitors. And it was much better: the clock was going slower by 4 mins during these 6 months. But I'd like to have even better results.
Unfortunately I don't have 12.5 pF capacitors, and couldn't find any (even on ebay). So I soldered one 10 pF and one 15 pF capacitor.
The question is is it going to be any better? What are consequences of soldering different capacitors to the quartz crystal?

UPDATE (01.11.2017): Please don't take the data mentioned above seriously regarging "...4 mins...". Most likely the battery depleted and the clock has to be reset. I forgot about that.
About 100 days have passed (since 23 July). The clock was running continuously and slower by 6 mins (41.6ppm). I desoldered 15pF capacitor and put back 10pF (now the clock has 2x 10pF capacitors).
UPDATE (11.08.2018) 227 days since last update. Clocks are slower by 17 minutes (52ppm). Soldered 2x 2pF capacitors. Will see, how it is going.


texts:
Here is a challenge we have a connector on a certin dvl(Doppeler Velocity Logger) and we cant get data from it. So we got a pinout,but without knowing pin 1 on the connector or what type of connector it is we cant do anything so here are some pics, I must note that my google search terms havent turned up anything yet but i will post update if they do. Good luck to anyone thats helping me. :)
[1

[![enter image description here][3]][3]

Anyway there is also written on the connectors FD6030 FD5285
and again good luck and thanks in advance.
EDIT: We are trying to get rs232-1

[3]:


texts: NFC Reader based project with microcontroller

texts:
I'm familiar with NFC technology on the Android side, since I've made several applications with it. I'd like to make a very simple microcontroller based hardware with NFC reader P2P involved for practice purpose.

Where is a good place to start for such project? What board and/or NFC reader is generally recommended for such case? For now, I don't plan to do anything fancy other than maybe just turn on some LED lights based on NFC reads. I am a software engineer, so I'm not too fond of Electrical Engineering but I do have some experience working with breadboards and programming simple micro controllers.


texts:
I've designed a LiPo charge/protect/boost circuit but am having problems with the DW01 protection IC. The IC successfully cuts off the battery when the voltage goes below 2.4V, but it doesn't auto-sense the battery voltage is back to normal. I have to disconnect the battery and reconnect it for it to work and it only turns back on this way if the voltage is >4.5V, which is too high. The IC doesn't detect over charge either. I've given it >5V and it does nothing. I used a bench power supply to simulate the battery voltages. I have an FS312F in the image, but practically it's a DW01 installed.

Additionally, if I short the CS pin of the DW01 to BAT- the output turns on again without me having to disconnect the battery.


texts: Do switching regulators usually require a lot of external components?

texts:
The DE2-115 Altera FPGA development board uses "LM3150 Wide-VIN Synchronous Buck Controller" to generate two supply rails:
1) 1.2V/5A from a 12V rail
2) 3.3V/6A from a 12V rail

These switching regulators require quite a lot of external components to be used. Is this common with switching regulators? Why not use an "integrated version" of switching regulators which do not require such a large number of different types of external components.


texts: How to check if there is electric current on material surface?

texts:
If there is electric current on a material surface (but not an obvious thing like outlet hole or such), what is the best tool to check it ? Is it possible to use multimeter?

Example case:
There is a new laptop I bought, once I connected the charger to AC current for charging the laptop, I noticed that wherever I touch any metal part on the laptop or certain surface area, I would get electric Shock. If I plug off the charger, there is no issue at all.

Assumed the issue is in the laptop, not the house's grounding or any, I want to return the laptop, but I need to show a proof to the laptop seller that the laptop has electric shock issue. In this case, what is the best tool to show there is electric current on the laptop ?


texts: Using both Synchronous and Asynchronous resets in a design

texts:
I am working on an FPGA design in which I also have to integrate several legacy IP cores. I use asynchronous assertion and synchronous de-assertion for the master reset signal in my design.
I observed that some of the IPs I got use synchronous resets while the others use asynchronous resets.

Will this create any issues during design implementation?
Do I have to modify the IPs to use a common reset method or can I just ignore this? (I have some restrictions in modifying some of the IPs)


texts: What is dynamic stability in an induction motor?

texts: What does dynamic stability mean in terms of a 3 phase induction motor when evaluating a slip/torque curve?


texts: Why are things like RESET/MCLR active low on most ICs?

texts:
Convention?

Easier to implement?

Another reason?

Is there a reason things like MCLR or RESET on microcontrollers are active-low, that is, you have to pull them down to reset the IC, and pull them up to "run" the IC.

I'm just curious because this causes me some problems. If it were active high, I could avoid the capacitor on MCLR required in some instances and deal with just a pull-down resistor. It seems only to add to complexity.


texts: Legal to use non FCC-approved radio devices purchased locally?

texts:
Does anyone know if it's legal to use non FCC-approved radio devices which are purchased locally? For instance, if the device is purchased from a local eBay seller, is it still legal to use it in any setting (commercial or otherwise)? AFAIK it is the importer's responsibility to ensure the device imported is compliant. So my take is that it is illegal to use unapproved devices bought from foreign sellers only. Is it correct?

EDIT: I'm referring to USA in particular.


texts: Is there a single IC that has both multiplexer and demultiplexer functions?


texts: Lithium Battery Pack - Do I need BMS within parallel connections?

texts:
Let's assume I am going to build a Li-ion battery pack with 12 18650s, where I connect four cells together in parallel and then the three sets of four in series.
My understanding is that a BMS (Battery Management System) keeps an eye on the voltage and keeps it from going too high or too low. Thus, would I then use a BMS module that connects three batteries in a series, or would I need to have a BMS with 12 connections, including the cells that are connected in parallel.
TBH, I am not at that level yet, but just trying to understand the nuances of li-ion batteries before I get my hands dirty.


texts: How to make a strong connection when soldering wires together

texts: I have two cut strands of string lights that I want to reconnect, but it's proving very difficult. They have a plastic/rubber coating around the wires which makes them stronger and more durable, but I need to strip it back to solder them together. Since the wires themselves are thin, they are particularly weak at the connection point where I solder them and they snap apart easily. Are there any tricks or trips to strengthen the wires where I solder them together?


texts: Using NPN transistors as on/off switches for a LED circuit

texts:
I have a very basic LED circuit:

simulate this circuit – Schematic created using CircuitLab

All D# are 3Vx0.02A LED. In order for this circuit to work, we need a 25Ω resistor for each LED quartet:

Total LEDs current = 0.02A*4 = 0.08A
Voltage drop = 5V - 3V = 2V
Resistor value = 2V/0.08A = 25Ω

I didn't have a 25Ω resistor, so I put a 27Ω resistor instead.

Now, I want to add an Arduino in order be able to power on and off each LED quartet programmatically. I don't want to overload the Arduino, so I thought it would be ok to have an external power supply which will give the LEDs all the current they need to work, without worrying about burning the Arduino itself.

I thought I could either use transistors or MOSFETs as logical on/off switches, but I chose transistor because they are way less expensive than MOSFETs.

I thought about getting a 2N3904, because it supports up to 200mA and the circuit requires 0.08A per LED quartet.

So far I know the circuit should look something like this:

simulate this circuit

I'm definitely not an electronic expert, I assumed it should be like that because I looked a site which talked about Arduino controlled LEDs via transistor used as on/off switches. It didn't explain a thing, it just had the circuit so what I want to ask is: why the 10kΩ resistor? Is the value right? Do I need a 1/4W 10kΩ resistor or a 1/2W one? The 27Ω resistor should remain 27Ω or should be changed when a transistor is introduced?


texts: Interpolation method for downsampling smartphone sensor data

texts:
I have a dataset containing lot of sensor measurements on Android smartphones, namely accelerometer, gyroscope and light sensor. The light sensor was sampled at a rate of 4 Hz and the accelerometer and gyroscopes were sampled with up to 500 Hz (depending on the device).
Now, I would like to downsample the accelerometer and gyroscope recording to 100 Hz and upsample the light recordings to 100 Hz.
Is cubic interpolation for upsampling the accelerometer and gyroscope ok or is it better to use linear interpolation? And what interpolation is typically used for a light sensor?


texts: Are the Offset Voltages in a Dual/Quad Op Amp Correlated?

texts: On a single piece of silicon on which there is more then one op amp, are the input offset voltages at all correlated, i.e. would they be expected to be same direction and similar magnitude?


texts: Method to determine angle of a rotating stage

texts:
I am currently working on a project that requires the rotation of polarizers to very specific angles. It is necessary that we are able to determine what angle the polariser is currently at so that we can make the motor stop when it reaches the required angle. The motor is currently run by an arduino reading commands from matlab.

I have been looking into optical encoders (with code wheel) and magnetic encoders, but I'm not sure of how to go about implementing them into my setup.

I would also like to note that light has to pass through the object we are rotating so mounting an optical encoder disk without a hole in the center would not work.

Would you have any suggestions for where to source optical encoder disks and encoders that might work for my setup?


texts: So I have this multi-tap transformer as a project. I bought the transformer, the only thing I did is the connections and the casing. When I tried to connect a 12v DC motor, the motor will vibrate like it is spinning but the rod/tip of the motor is not. Sometimes it spins clockwise or counter clockwise. What is the problem? Help please.


texts:
I have the following signals and their Fourier transforms: \$x(t)\$ and \$r(t)\$. The signals are limited such that \$X(e^{j\omega}) = 0\$ for \$|\omega| > \Omega\$ and \$R(e^{j\omega}) = 0\$ for \$|\omega| > 3\Omega\$. I'm constructing \$y(t)\$ through combinations of \$r(t)\$. The signal is then sampled with a sampling period of \$T\$ and frequency of \$ \omega_s = \frac{2\cdot\pi}{T}\$. I have determined the following Nyquist rates for the following \$y(t)\$.

For \$y(t) = x(t) + r(t)\$ my \$\omega_s = 6\Omega\$. However, for \$y(t) = x(t)\cdot r(t)\$ and \$y(t) = (x\star r)(t)\$, I'm not sure how to proceed. I know that multiplication in time is convolution in frequency and vice versa. But how do I apply that concept to finding the Nyquist rate?


texts:
I am currently prototyping a custom intravenous medication delivery system. An AtTiny85 microcontroller is being used to control two L293D drivers, with 4 pins programmed to send a pulse train to both drivers and an additional pin being used to enable/disable each driver by way of an NPN/PNP logic system.

This leaves no remaining pins on my setup (the AtTiny85 is built into a 5V Trinket). I need to be able to externally control when this program is executed, and I have been doing so by shorting the Rst pin to ground, thus calling the setup() routine in which my algorithm is nested.

This is where problems arise: I have attempted to short to ground the following circuit, from which external feedback is provided from an NI I/O device:

simulate this circuit – Schematic created using CircuitLab

However I have found this method to be unreliable - a 150 ms NI TTL pulse properly forces a reset on the AtTiny85 about 75% of the time, yielding the proper series of events. A proper reset fails to occur about 25% of the time, indicated by the lack of red light on the unit. Suggestions?


texts: SRAM Chip. Entering the data either manually through DIP Swithces or from the bus

texts:
I'm building a 8-bit "computer" on the breadboard mostly following tutorials from different sources. The project is educational, so I want to be able to execute all the steps manually and see what is happening through bunch of leds hooked up almost everywhere :) Now I'm designing the SRAM module that could work in two modes

Controlled by the CPU control logic.
Controlled manually.

The second mode is required to be able to enter the data/commands into the SRAM through DIP switches. In this way I can program the "computer" I'm building, switch it then to auto mode and run the program.

I came up with the following schematics. The idea is to hook-up all the control pins through the multiplexer that either hooks up it to the control unit or to some preset signals, so that address/data go to the chip either from the bus or from dip switchers.
As a mux a can probaly use this thing SN74HC157.

So the questions are:

Do you think the design will work?
Is there any other way to make it simpler? :)

Thanks a lot.


texts:
I am trying to use four MUXes to send 4x8 identical sensors onto an I2C bus. Let's call my four types of sensors A,B,C,D. Eight of each means 32 sensors that I need to 8:1 MUX onto one I2C bus.

I'm trying to accomplish this with top sheets and multichannel design. From the picture below, you can see that I have a Sensors.SchDoc sheet repeated eight times. It has four distinct sensors on it, repeated eight times, but I have only shown two of them in the picture for simplicity. I send the 1..8 SDA lines on four busses and the 1..8 SCL lines on four busses. Then all 64 outputs (32 data, 32 clock) go into the I2C MUX (TI TCA9548A) and create one pair of SDA and SCL lines (RM_I2C1_SDA and RM_I2C1_SCL) which go to my MCU.

This shows my top sheet with the 8x repeated Sensors.SchDoc bussed into the single SDA Multiplexers.SchDoc sheet with four multiplexers on it.

Here is my first Sensors.SchDoc sheet.

And here is one of my repeated Sensors.SchDoc sheets. You can see the the U? and C? designators are updating, but not the ports, which I need to be BME680_SDx depending on the sheet number.

Here is my multiplexer sheet. Each of the four MUXes share the same output SDA and SDL nets which go to the MCU.

It's been a painstaking naming process and I've got a bunch of compiler errors.

I've already referenced these articles:
Altium. Multichannel design. How to specify the repeat(port) connection order?
Altium: Harness as output of MultiChannel block
https://techdocs.altium.com/display/ADOH/Multi-Channel+Design+Concepts

I'm guessing I need to use the REPEAT() function somewhere but I tried it for my Sensors.SchDoc sheet ports but then I got errors saying that my sheet port names didn't match my schematic port names.


texts: User controlled storage devices existence

texts:
Today's memory devices have a lot of logic embedded before data is actually written onto the NAND pages.
An example could be wear levelling algorithm , FTL functionalities etc.

The typical life of a NAND cell would be around 100000 cycles of operation.

My question is:

Can the storage devices performance be maxed out if all of the internal logic were removed?
(Assuming I dont care what happens after 100000 cycles. I just need speed for 100000 cycles and then, before the end, I would backup and use another storage.)

Are there any such devices out there that allow me to disable such logic?

How practical are such devices in terms of speed improvement (if they exist?)


texts: Is it possible to have phase shift with only passive (resistor, cap, inductor) components?

texts:
I know that this can be done somewhat because voltage will lag current on a capacitor etc. But I want to see if it is possible to take an AC signal and output the same signal but with some chosen phase shift (x degrees) using only these components, I know it can be done by adding op amp or transistor.
What I want is to sample an AC signal at the same frequency but at different phases, ideally more than 2. So sample at 50degrees, 60 degrees, 90 degrees etc.


texts:
I am working on an adapter that will allow a device to be connected to both a PC and external power supply. I am wondering if I will need to isolate the 2 5V supplies with a DC/DC converter and some opt-couplers or will I likely get away with what I have below?

Am I completely off here or am I heading in a reasonable direction?

EDIT: This is a computer talking to a tablet device.


texts:
Assuming ideal op-amplifiers, I did the following steps:

\$v_{out1}=v_1\frac{R_2}{R_1}=2v_1\$

\$v_{out2}=v_o=\left(\frac{v_{out1}}{R_3}+\frac{v_2}{R_4}\right)R_5=4v_1+2v_2\$

My textbook claims \$4v_1-2v_2\$


texts: 'Footprint Field' visibility options in Eeschema (Kicad)

texts:
I have added the footprint information to various components in Eeschema (e.g. added sm0402 to a resistor).

A purple label then appears indicating the that a footprint has been assigned.

Is there anyway of globally turning the visibility of the the footprint fields on or off? So I can chose to view or not view all the little purple labels.


texts: I have found somewhere the following scheme for an arduino based geiger counter. (The arduino main purpose is to count the pulses from the tube) As far as I can understand it, the transistor would amplify the small current coming from the tube and the arduino would then detect a low logic level when a ionizing radiation is passing. My doubt is about the capacitor: why is it there? I have tried to build the circuit simulating the passage of radiation by pressing a button. I tried to remove the cap from the circuit too, and yet the detection is noticeably more accurate with the capacitor in. I guess it is because the capacitor is like a filter for "false pulses".Can someone please explain me the role C1?


texts:
We use pads where the pad itself has no diameter (but the accompanying hole does) as break lines in our PCBs. Often those are only 3-4 and can be placed by hand. Now we have a PCB with a break line requiring more of those and closer together (12+ holes).

Doing such by hand is possible but tedious. Can macro's in Altium be used to semi-automate this process?

There's an overlay line present to guide the process and the lines are usually in a 90 degrees angle (so only x or y increments/decrements).


texts:
I intend to send some information through GET method to a php page using the SIM900 module.

I tried the following sequence of commands with success.

AT+CSQ
AT+CGATT?
AT+SAPBR=3,1,"CONTYPE","GPRS"
AT+SAPBR=3,1,"APN","internet"
AT+SAPBR=1,1
AT+HTTPINIT
AT+HTTPPARA="URL","www.my_URL.com/stuff.php?variable=TEST"
AT+HTTPACTION=0
AT+HTTPREA

Note that my service provider doesn't require username & password for accessing, also "internet" is the name of the APN.

Afterwards, I wrote a program on the mbed, that sends this code to the module, then wait for a pre-determined amount of time, read the response and proceed.

I started getting an error specifically on the AT+SAPBR=1,1 command. I tried the commands manually and now I always get the error on this command. This is the comand that opens the bearer.

What I have tried: On the AT+SAPBR=? command, the second parameter is the bearer ID, so I tried using, for instance, 2 instead. And it works.

I find this very strange and I'm trying to figure out why '1' as ID keeps getting me stuck?