texts: How to move a magnet to a specific coordinate on a board

texts:
I was just reading about Claude Shannon's famous maze-solving mouse, Theseus, which used a movable magnet under the maze to draw the mouse in a given direction. I'd like to play around with this idea.

I'm trying to decide the cheapest and simplest way to have a square board of, say, 40cm by 40cm, and programatically move a magnet on that board to a given coordinate with reasonable precision.

My first thought was to position a series of electromagnets at the edge of the board that, when activated in various combinations, could exert the correct force on the movable magnet.

This seems like a fairly crude solution that would be difficult to control with accuracy. I also thought of placing a matrix of electromagnets under the board and activating them in a timed sequence, but this seems like an unnecessarily complex solution requiring far more parts and pins than necessary.

I remember enough EM that I think I could work out the necessary field equations to get the magnet where it needs to go, but am unsure how to best create that field.

Or maybe I'm thinking about this all wrong??


texts: Help with reverse engineering a small PCB

texts:
I need to reverse engineer this small board (7.5 x 28 mm) which serves an inductive proximity sensor. I suspect some of the components are dated/obsolete but the board works well. Ideally I would end up with an equivalent schematic.
Determining the various resistor values is easy enough but I lack the tools/knowledge/skill to identify the other components, measure capacitor values and trace the overall circuit.
I did some hunting but had no luck finding a service that would do this.
Anyone aware of such a service and/or options to decipher this little guy?
Much thanks for any and all advice.
UPDATE
A year later and after some prompting from Bruce Abbott, I finally battled through creating a schematic for this board.
While I believe I was able to identify all the components, I'm unsure which ones support the oscillator, detection circuit, and output circuit.
I would be enormously grateful for some expert input on which do what and whether the circuit below looks functional.
Much thanks!!

More useful view.
Better still would be a vertical view of each side with sensor bent at 90 degrees to the board so we can see under it.
Here the bottom side / right hand image has been flipped horizontally so the layout matches that of the other image.


texts:
I am trying to design a simple PCB, using Cadance 17.02 , after importing schematic to PCB designer all footprint pin have DRC Error. the Error is :
"Thru pin to shape spacing" with  both actual and Require value of zero.
How can I correct the Er?


texts:
I have a little USB flash drive which the plastic cover has broken off of. It still works fine, but I often have the thing in my pocket or in the bottom of my bag. I don't want the bare board to get damaged by my keys or something. Would covering the board in glue from a hot glue gun be a reasonable casing to protect it?

I've used glue gun glue to help hold together and insulate small arduino circuits before without any troubles, so my intuition tells me that this should be fine, but my experience lies more on the software side of things, so I'd like to check with a few others before I attempt this.


texts: Hartley Oscillator Alternate Oscillation Mode

texts:
I've been trying to build a hartley oscillator and have almost succeeded, however my calculations are off by appx 1000 relative to the measured waveform. AND the kicker is that it only works when I pull out the 1u capacitor in the tank circuit. I believe that I at least have to start it with the cap in the circuit but the waveform doesn't appear on the scope until the cap is disconnected. The scope shows a waveform of 1.6mhz while I believe its supposed to oscillate at 1.6khz. Is there a separate mode of oscillation that I am seeing? Without the cap, is it just a series RLC filter in the feedback loop only allowing amplification of the series resonant frequency?

I tapped the 100u inductor at about 40/60 and have flipped it's orientation several times to try and get the gain at an acceptable level. I modeled the resistor in the tank circuit to account for inductor resistance. I wonder if the gain just isn't quite right for the intended 1.6khz oscillation, but turns out to work for the alternate series mode of oscillation. Does anyone have any insight on what's going on here?

One final point of weirdness is that upon trying to alter the series RLC feedback path by changing the emitter bypass cap to only 1u (as well as changing the other series caps) but none of this altered the waveform shown on the scope!


texts: Which technique do I use to solve this problem?

texts:
I'm currently working on open questions for my Physics 2 exam about eltric fields, magnetic field, circuits and so on.

I'm currently stuck with this problem:

I'm asked to solve for the voltage $$U_X$$ In our previous circuits I was always able to use Kirchhoffs Law to solve for the voltage but now I'm stuck because I don't really how to apply it to this one.

It would be great if someone could help me out with this one.


texts: What to look for when buying a "helping hand" device?

texts: I'm considering buying a "helping hand" and this one looks interesting to me. Since I'm pretty new to hobby electronics, my question is what are important things to look for when purchasing such device?


texts: Voltage transfomer without ground connection

texts: today i bought a transformer 200v to 110v for my soldering station hakko fx-888D however it doesn't have a ground connection. Is there any problem if i connect the soldering station to it?


texts: Connection between Chassis GND and Circuit GND for ESD/transients

texts:
All of the images in this post are from Henry Ott's Book, Electromagnetic Compatibility 2009, and I would like some clarification on some things about them.

Figure 14-14 seem to be in conflict with Figure 3-24 and 15-15.
The circuit GND is connected through a TVS to chassis GND for 14-14, but in the other two, the circuit GND is connected directly to chassis GND. Is anyone able to reconcile this?
Also confusing me is 14-14a where circuit GND is connected to chassis GND via a TVS. As drawn, it doesn't look like it would protect from a transient across GND-PWR in either polarity until it is double the tolerable value. Similarly, if it were a unipolar circuit and unidirectional TVS diodes were used, it would not protect against a transient where GND becomes more positive than PWR. What's going on here?

UPDATE:
I found this diagram and text which helps clear things up:

So I guess the wire tie between circuit ground and chassis ground is supposed to keep the two at equal potential over long periods of time but cannot be relied upon during ESD due to inductance. In which case the TVS diode tying circuit ground and chassis ground at the point of entry stops the circuit ground from straying too far from chassis ground during an ESD event. I assume pin 1 on the RS-232 connector here is the connector shell in direct contact with the chassis/enclosure.


texts:
I'd like to make use of object-oriented practises inside a FreeRTOS application. Is this as simple renaming files with task functions as .CPP, and instantiating objects, etc. inside the function, compiling as you normally would? Or, is some configuration involved?

Perhaps somebody could demonstrate with a sample "blinky" example, where the task itself is a C function, in which an object of some sort is created and used.


texts: Can Flash controllers make a card readonly?

texts:
It is said in this answer here that

  Some of them have a controller chip that will permanently lock them to
  read only if they detect a write error, as a preservation measure.

Is it possible for a flash controller to permanently lock a SD card into readonly such that it cannot even be formatted?


texts: which power supply rating do I use for my diy led light panel?

texts:
I'm building a led light panel using 24 x 18W SMD 5630 72LED Rigid Light Strip Tube Bar Lamp Bright White 12V 1800LM connected in parallel so whats the power supply rating

Specifications for each lights strip:

Key Features: LED Light
Light Source: 72 LED
3.LED Size: SMD 5630
Luminous Flux: 1800LM
Output Power: 18W
Voltage: 12V
Light Color: White
Color Temperature: 6000K
Lifespan: 30000-50000 Hours
Material: PC & Aluminum
Dimensions: (100 x 1.8 x 1.5)cm / (39.37 x 0.71 x 0.59)" (L x W x H)
Weight: 6.7oz / 190g


texts: What is the function of a Fourier Series?

texts: What is a Fourier Series?  What it is used for?


texts: Combine a vhdl and verilog configuration file

texts:
I'm trying to create a simple proof of concept regarding the configuration of our testbench (binding the correct entities to components/modules).

The structure is as follows:

top(VHDL entity)

--sub_vhdl(VHDL component)

--sub_verilog(Verilog component)

----sub_sub_verilog_1(Verilog component)

----sub_sub_verilog_2(Verilog component)

I want to be able to control which VHDL entity sub_vhdl binds to, and which module sub_sub_verilog_2 binds to (for simulation in Questasim).

As far as I understand with a VHDL configuration file I can control the binding of sub_vhdl and sub_verilog, but it can not define the modules lower than sub_verilog.

And if I would write a verilog wrapper for the top entity I would have the opposite problem (not being able to control the binding of components to entities of the VHDL structure).

Is there a solution for my problem ? Some scripting (for example generating the VHDL config file with a script based on the situation) is not a problem.


texts: I want to reverse engineer the circuit from an insect swatter. However, there is this 'white sticker' at the back of the circuit. I am assuming this is for some kind of protection or just to hide the circuit. Is it safe to remove this? And what tools/methods can I use if it can be removed? Thank you.


texts:
I'm using a M48Z02, a 5 V 16 Kbit ZEROPOWER SRAM.
In absence of power, according to datasheet information, this device can hold data for years:

A [...] package houses the M48Z02 silicon with a long-life lithium button cell to form a highly integrated battery-backed memory solution.
The M48Z02 button cell has sufficient capacity and storage life to maintain data functionality for an accumulated time period of at least 10 years in the absence of power over commercial operating temperature range.

What I'm experiencing is a problematic data loss that make this chip untrustworthy.
I've created a small circuit using a stripboard to only read the M48Z02. I manage the circuit through an ON/OFF switch that connect the power source.
This schematic should explain:

simulate this circuit – Schematic created using CircuitLab
About 5 hours ago I've programmed my SRAM and than inserted it into the stripboard manager. Now, when I wake it up it shows wrong data in some addresses.
My questions:

Is possible that the battery failed and data were corrupted?

Is possible that some data were corrupted switching it on and off because of power pins are directly connected with control pins? If yes how avoid that?

NOTE: I presume that this isn't a problem about a buggy chip because 3 M48Z02 of mine have this problem.
EDIT:
a)

What is a stripboard manager?

A "case" for the chip that helps to manage it:

b) When I say switch on/off I mean:

my power source is OFF and the chip is in his case.
I power ON the circuit
after reading data I switch OFF the power source
the chip is disconnected and (maybe) programmed again

c) About the heat:
I've noticed that when it fail or if I switch on/off power source frequently it becomes hot. Also it becomes very difficult to write new data on the device... but not impossible.
Any help you can provide will be really appreciated.


texts: Control latching pulse-solenoid-valve with MOSFET Array

texts:
I have a setup where I need to control a solenoid-valve via a microcontroller.
The solenoid-valve needs a 50ms \$\pm\$6V with around 250mA to OPEN and another 50ms pulse of now inverted \$\mp\$6V to CLOSE again.

My idea was to use a MOSFET 2N/2P-CH array (TC8220K6-G). Attached the idea of my circuit.

Now I know, that solenoid do kick-back voltage due to their inductance and one should use a flyback diode. The problem is, that in my case I would need to put 2 Diodes in each direction which would result in a short circuit.

Any idea how to deal with this problem? Or has someone a better idea to control such pulse valve?


texts: Linear regulator to step down voltage from 3.7V to 1.5V

texts:
I have a coreless drone motor that connects to power through MCP73833 that connects to a 3.7V LIPO, but the motor is too loud so I want to reduce the speed a little. I figured, the easiest way to do it is to reduce the voltage to the motor. Is it possible to use a linear regulator chip to reduce 3.7V to 1.5V to achieve this goal (reducing RPM).
Maybe use something like LM3670MF-1.5


texts: I designed a circuit that requires buffers with the control gate (not like the ic's that have the control that will make every buffer turn on or off) .  I am wondering how this works, and how it can be implemented with common npn transistors. Is the control just placed on the VCC of each buffer, therefore disabling it without power or is it something more complex?


texts:
'Stackable bus connectors' are common nowadays on Arduino and other boards where a single connector has both the male pins (for the board below) and female sockets (for the board above)

In DIY sites there are instructions on how to solder these to the board. This isn't tooo hard.

But what do you do when you have a PC104+ 4x30 (120 pin) connector?

Soldering these by hand isn't easy and very time consuming but possible.

BUT, what do you do in mass production? you can't move these connectors through wave soldering as solder will get attached to the male pins and you can't have paste on the holes.

Any ideas on how this is done? I have a hard time believing this is done by hand. In the past there were press-fit connectors (still available today) but these are rare and quite expensive.


texts: 20 mA current loop speed/distance trade offs?

texts:
By 20 mA current loop, I'm referring to digital current loop communications, e.g. the standard used by old Model 33 teletypes.

(Image credit: By Rama & Musée Bolo - Own work, CC BY-SA 2.0 fr, https://commons.wikimedia.org/w/index.php?curid=36769003)

It was my understanding that the distance limits of a 20 mA current loop were due primarily to the resistance of the wire in the loop, and that adding voltage to the current source input could be used to drive even loops in excess of several miles.    Speed was obviously limited by the teletype electromechanical mechanism to about 10 characters per second, which worked out to 110 baud (bps.)

These days, the teletype electromechanical mechanism is only a museum piece, but the advantages of current loop communications remain, though it seems they are more frequently found in industrial analog sensor circuits.

I believe many modern high-speed communication mechanisms (like LVDS) are effectively current loop as well, but without the same long-haul wire goals a teletype had.

What are the speed/distance limit trade offs if a digital current loop is implemented with semiconductors over existing telephone wires (e.g. cat 3)and allowing open-circuit voltages up to 100 volts DC?

For example, if I want 1 Mb per second, how far will current loop drive a twisted pair point-to-point given the above limits?   How does this compare with RS-422 and CAN with Flexible Data-Rate (CAN FD) networks?

I'm giving the circuit editor (and my rusty electronics education) a try to illustrate what I'm thinking of.   Component values are estimates, including the 151 ohms for about a mile of cable.    I presume the two communicating systems have a isolated local grounds, not connected to earth ground, and that any needed opto-isolators are on the other side of the SoC chip.   I'm treating the comparitors as ideal, and thus ignoring the common mode DC offet the switch might produce, I chalk it up to lack of practice laying schematics.

simulate this circuit – Schematic created using CircuitLab

Rethinking regarding the "termination resistors" across the switches, perhaps both R2 and R6 should be about 20K ohms.

I expect I should be modeling the twisted pairs as a transmission line, rather than just R7, but I've forgotten how to do that.


texts: Does the 802.3 Ethernet standard provide a recommended circuit design?

texts:
I have a project I am designing whose fundamental parts consist of sensors connected to a micro-controller. the micro-controller will then send the data out over an ethernet port using standard tcp/ip protocols. I have already created the a proof of concept for the project using an Arduino Yun, but ran into several issues when the libraries and apis that make the Arduino easy to use seem to have prevented me from directly manipulating the registers that control the Arduino's ADC. Additionally, designing the physical ethernet circuitry would allow me to be more flexible with the board layout and housing design and allow me to choose micro-controllers without built in ethernet circuitry if I wish. However, I am having trouble designing the ethernet hardware due to my limited experience.

It would help me greatly if there were circuit designs I could use as a reference when designing my circuit. Therefore my question is does the 802.3 Ethernet standard have a set of recommended circuit designs in schematic and/or block diagram form or does it solely lay out the features and functions for the standard? It would also be a helpful if someone could point out some surface mount ICs commonly used in mass manufacture Ethernet socket designs.


texts: How to clean DUST stucked due to moisture on pins of chips ICs of motherboard circuits

texts:
Which chemical can I clean my old motherboard with, whose electronics components chips pins like ICs capacitor transistors diodes have dust stocked their color has been changed to black yellowish reddish?

I had cleaned the motherboard with isopropyl and dried it. Some major parts of PCB dust were removed but some dust stuck on pins did not get removed.

After cleaning I gave to the technician for repairing as after cleaning drying the boards were getting power CPU SMPS fans were moving but not giving displays and give fluctuating errors on debug card so technician told me to clean pins also.

Attaching images for showing the pins hope you can find what it's technically termed or called, maybe corrosion of pins.

Saw in YouTube video to clean with detergent and tap water but for years I have heard from people that electronic parts, especially mobile laptops, should not come or wet in contact with water.

Will water and detergent powder and drying in the sun (as I don't have a hot gun or hair dryer to dry it) be safe to electronic PCB, as moisture has stuck the dust to circuit previously also will washing with water detergent work?

Have googled and funded about contact cleaners will it be OK for cleaning pins if IC chips transistors

As some boards are expensive I don't want to throw or scrap them kindly tell me how to get rid of dust moisture.

Waiting for technicians experts advice for cleaning pins dust moisture.

  I request moderators and users not to flag or declare question duplicate elaborate or out of the topic or out of focus as it is within topic electric circuits PCB related and I tried to be specific brief with appropriate details of problems I need to some expert advice from experts and technicians engineers professionals and users.


texts: Are horizontal and vertical back porches required for digital video, and if so, why?

texts:
The necessity of vertical and horizontal front and back porches in analog video seem fairly intuitive to me, but why are they necessary for digital video at all? In this LCD module data sheet and this NXP presentation, the front and back porches are referenced, but their necessity is not explained.

I am assuming it doesn't take any more time to move a pointer from one pixel to the next adjacent than to move it to pixel (0,0) for the beginning of the next frame.

What am I missing here?


texts: Modeling the Diode forward Characteristic

texts:
I want to know easiest way to remember the modeling methods.

What I have figured out, is that we only have to find out resistance of diode in case of small signal model, otherwise we will be provided with the diode resistance in any case. Is that right? If not, then what are the formulas for that? Or how to find them?


texts:
Hello!

I have a simple question concerning this circuit I have built:

It is a 555 Voltage Controlled Oscillator I have built as a foundation for my signal generator circuit. The circuit works great, changing the frequency as I turn the pot - but I am confused about the speaker connection.

I have one cheap speaker I use to test my circuits (3W, 8Ohm) that (obviously) has two input wires, + and -. I tried connecting the + wire to the pin no.3 (OUT on the schematic) and - wire to ground, but there was no sound.

By trial and error, I figured out the speaker is only working when I connect one wire (I know they're interchangeable) to the OUT (no.3) pin and the other to VCC, which is +9V to ground in my case.

I am really confused by this, since I thought DC will damage the speaker, but in my case it's working just fine. Can anyone please explain why is the speaker working with the circuit like this? The only thing that came to my mind is that the output is inverted somehow.
I am sure it's trivial, but I just can't get my head around it.

Thanks for enlightening me!


texts: What's this special type of PCB prototyping board called?

texts:
I'm trying to buy some prototyping boards for basic, learner electronic hobby project building, but the ones I'm seeing are merely grids with a separate and distinct via for each independent hole.

I saw a picture of one prototyping board that was without copper through-hole vias, but instead had rectangular silver connectors that spanned multiple holes (most span 3 holes, but there are also 2-hole spans, 1-hole spans, and many hole spans on the same board).

It's almost like a quasi-breadboard PCB in its function.

Does anyone have any idea what I'm talking about? I'm trying to find the picture of the hobbyist project I saw that used it.

I don't understand what would be the usefulness in using a board other than this one? With copper via proto board -- do you have to solder and link multiple wires into one hole? That type of board seems like it'd be extremely difficult to solder junctions of more than one wire.


texts:
I have everything right now, but the output I desire should be 00 00 11 00 00 00 00 10 00 00 00 when the clock is 1(z1z0). Can someone tell me what is wrong with my code? I've checked my Kmap numerous times.

The JKFFs I should be implementing is:

module csm51a_proj3(
input r,
input x1,
input x0,
input clk,
output z0,
output z1
);

jkff i_jkff
(
.r(r),
.x1(x1),
.x0(x0),
.clk(clk),
.z0(z0),
.z1(z1)
);
endmodule

Below is the jkff implementation:

    module jkff(
input clk, r, x1, x0,
output wire z1,z0
);
reg s0,s1;
initial begin s0<=1'b0; s1<=1'b0; end
assign z0=(x1&&!s0&&s1);
assign z1=(s1&&x0&&(!s0||x1));

wire a1, a2, a3, J1, K1, J0, K0;
assign a1=(x1||s0);
assign J1=(a1&&x0);
assign a2=(x1||!s0);
assign K1=(x0&&a2);
assign a3=(x1||s1);
assign J0=(x0&&!s1);
assign K0=(a3&&x0);

 always @(posedge clk or posedge r)
 begin
    if (r) begin
        s1<=0;
        s0<=0;
        end
    else begin
    case ({J1,K1})
    2'b00: s1<=s1;
    2'b01: s1<=1'b0;
    2'b10: s1<=1'b1;
    2'b11: s1<=~s1;
    endcase
    case ({J0,K0})
    2'b00: s0<=s0;
    2'b01: s0<=1'b0;
    2'b10: s0<=1'b1;
    2'b11: s0<=~s0;
    endcase
end
end
endmodule

Below is the test bench

    module csm51a_proj3_tb(
    );

    reg reset, clk, x1, x0;
    wire z0, z1;
initial begin clk=0; end
always begin #5 clk=~clk; end
    csm51a_proj3 csm51a_proj3
    (
    .r(reset),
    .x1(x1),
    .x0(x0),
    .clk(clk),
    .z0(z0),
    .z1(z1)
    );
    initial begin
    reset=0;x1=1;x0=1;//clk=1;
    #10;
    reset=0;x1=0;x0=1;//clk=1;
    #10;
    reset=0;x1=1;x0=1;//clk=1;
    #10;
    reset=1;x1=0;x0=0;//clk=1;
    #10;
    reset=0;x1=0;x0=1;//clk=1;
    #10;
    reset=0;x1=0;x0=1;//clk=1;
    #10;
    reset=0;x1=0;x0=1;//clk=1;
    #10;
    reset=0;x1=0;x0=1;//clk=1;
    #10;
    reset=1;x1=0;x0=0;//clk=1;
    #10;
    reset=0;x1=1;x0=1;//clk=1;
    #10;
    reset=1;x1=0;x0=0;//clk=1;
    #10;
    end

endmodule


texts:
I am trying to build a double dice circuit. I tried one example I found from the  web. But, I have problems with leds, and I am not very familiar with proteus. Could you please tell me why my LEDs are not working?

Original source:

RM: Found elsewhere - similar and may be meant to be identical - may be clearer.
From


texts: 4*4 reverse matrix code in matlab wich has variables

texts: Here is the system of which I have found the state space equation. I need to get the transfer function. [SI-A] is a 4x4 matrix and it's so hard to get the reverse of it. What is the Matlab code of 4x4 reverse  matrix such that we do not have number just variables?


texts: I am doing my first altium project and I got this weird top overlay gerber file. How do I get rid of the bottom logos?


texts: Questions with overhanging silkscreens in eagle cad

texts:
I am currently using several footprints in my pcb design which have tPlace silkscreens that extend beyond the board boundaries, and I was wondering what the implications of such silkscreens are since they are not cropped up in the resulting gerber files? Will a PCB shop normally disregard any design elements that hang beyond the board boundaries, or will these silkscreen elements cause issues in board layout, either artificially extending the board dimensions or causing problems at the board shop where my silkscreen overlaps other boards?

I am using the tPlace elements of other components on the board to determine the orientation of various smd devices, so I don't want to simply remove the tPlace layer from the cam job.

Is there any way that I can crop these tPlace entities without manually editing the individual footprints, or does it matter at all?


texts: I2C Pull-ups with Multiple Power Supplies

texts:
If I have an I2C Master with multiple I2C Slaves all on separate 3V3 lines (i.e. 3v3_Master, 3V3_Slave1, 3V3_Slave2... etc.) does it matter which 3V3 line the pull-up resistors on the line connect to?

I've looked through the I2C Manual here but couldn't find the answer.


texts: Do any commercially available generic circuits use only discrete components?

texts:
I'm currently toying with embarking upon a totally crazy hobby project, which would prohibit the use of any component that cannot be 100% verified manually: obviously this completely rules out all forms of integrated circuit—even discrete components would have to be manually tested and verified.

On the other hand, it does not rule out the use of pre-made circuits: provided that they can be verified (e.g. following the circuit tracks and testing individual components).  It would be a significant timesaver if such pre-made circuits existed for generic tasks typical of basic ICs.

I appreciate that there's pretty much no demand for such circuits (except perhaps at a basic educational level), so imagine that they are not commercially viable.  Certainly my searches so far have not uncovered anything.

But do they exist?  Does anyone sell generic logic circuits from discrete components?


texts: 74HC4051 Alternative - 4 Channel 1 circuit?

texts:
I have been playing with this multiplexor recently: 74HC4051.

I have been searching all day for an alternative version where it is 4 channels instead.

My task is simple and perhaps I am using the wrong component which is why I can't find a low-cost component that allows me to do this.

I have 4 LED and 4 transistors. My scenario "processor" has 2 digital inputs,

My task is to switch each transistor at a time, in turn, the LED will be switched on.

Is a demultiplexer the correct component for this? Any help is appreciated, I am quite new to hardware design and am trying to learn about the different types of components available.

What options are available?

Thank you very much for your time!


texts: Absolute difference with logical operators only

texts:
I'm trying to implement in a FPGA the test formula:

abs(a-b)>1

a and b are unsigned 3 bits (0 to 7).

The truth table is as follow:

The test is:

reg[2:0] a, b;
((a > b + 3'd1) || (b > a + 3'd1))

A "dumb" test without the "+1" operator would be:

[a==0 && b>=2] || [a==1 && b>=3] || [a==2 && (b==0 || b>=4)] || [a==3 && (b<=1 || b>=5)] || [a==4 && (b<=2 || b>=6)] || [a==5 && (b<=3 ||b==7)]

There is obviously symmetry. How could I implement with only logical gates (or with a few tests)? The objective is to have something the simplest possible (aka. taking the least area space) and I would like to avoid any 'complex' operator.


texts: Accurate determination of resistance of transformer

texts:
Based on this transformer:

Is it accurate that you can get the resistance of utility pole transformers simply by getting the xformer powerlosses at full load and deduct it to the xformer powerlosses at no load, then dividing it by xformer rated current squared as in the following?

Powerlosses noload=43 W [mainly magnetic core losses only-negligible copper losses]

Powerlosses fulload=758 W [magnetic core losses and copper losses]

Irated=75000/240=312.5A

Resistance of transformer = [Powerlosses fulload- Powerlosses noload] /Irated^2= 0.0073216 ohm.

Is the above accurate?


texts: Drive 12v solenoid from Raspberry Pi using transistor

texts:
I'm looking to drive a 12v solenoid from a Raspberry Pi's GPIO. I have been looking at using a S8050 Transistor, however have been looking at the datasheet and have been struggling to determine whether it is suitable or not.
The \$ V_{cbo} \$ and \$ V_{ceo} \$ are both comfortably over the 12V required for the solenoid, however the \$ V_{ebo} \$ is 5V.
I apologise, I'm still quite new to the specifics of transistors, I'm aware of how to use them (I think!) but I'm not confident with specifying them, and assessing whether they are fit for purpose. Would anyone mind perhaps explaining whether or not this transistor would be suitable to drive this solenoid and why, and what I should be looking for when specifying a transistor please?
I have attached an image of my simplified circuit diagram below.

The solenoid is rated at 12v, 0.6A, similar to the one listed here: https://www.ebay.co.uk/itm/193480469509 I apologise for the use of an eBay link in this case, however I am struggling to find any useful proper datasheet matching this item.
S8050 Datasheet: https://datasheet.lcsc.com/szlcsc/Changjiang-Electronics-Tech-CJ-SS8050_C2150.pdf


texts:
I am looking to recreate a switch circuit I have seen on an intercom system. The switch allowed for two functions, while using one momentary switch.

When the switch was pressed and emetily released, the switch latched on. It then could be pressed and emetily released, which resulted in the switch turning off. This was useful for talking on the intercom for extended periods of time.

The second function was when the switch was held for a few seconds. If the switch was held for longer than about 1-2 seconds the switch would remain on until the button was released. In this operation the switch would act as a momentary switch, useful for saying a few words into the intercom.

I am interested in breadboarding a circuit that could accomplish this. I would like to know what I will need to get this working and how to wire it up.

-Thanks very much!


texts: Capacitor as one piece voltage controller for wind turbine

texts:
I an electronic engineer and renewable energy engineer specifically.  I am working on designing a new turbine and needed some help with a much simpler idea I had.

A while back I was working with smaller 500 watt to 1000 watt wind turbines that generated low voltage (24/48 V)  However I am working on a new design for a peak of 3.6 kw and I am currently using a chinese PWM controller for a steady 380v output.  The alternator generates higher voltages but will require over speed of the generator.  I'm looking to custom design a capacitor for a complete one piece regulator for this.  I have some questions I could use some help on.

How do I determine the heat dissipation (in watts) of a capacitor I can't seem to find much information on this.  Of course I have found tons of literature on how hot it can get and sometimes a max draw but it's rare.  I would like to use a very large capacitor to stall the turbine above 380V (to prevent over speed) and to divert extra power to heat.  This would be a rare need as the inverters i am using have a input range of 200 - 600v so it's rare that i need to reduce the voltage.  It's more for the protection of the bearings.  I've been looking at some Air Capacitors but generally those are very high voltage.  I'm really needing a cap that is 380v - 480v and can clamp the turbine down when the winds are super high and prevent over speed.  I can do this with some smaller capacitors but the heat builds up and they just can't handle it.  I've tried some larger capacitors too but I'm just needing some help calculating maximum voltage clamping capabilities.


texts: Data + Power connector and cable suggestion

texts:
I need to decide about how to connect two custom designed electronic units. One is main (execution) unit, and the second is hand-controller unit. Those units have to be connected by wire. The communication between units require 3 twisted pairs (for data transfer) and power supply lines (VCC and GND). The power lines are needed for hand-controller supply from the main unit. The power supply is 6V with max current consumption of 500mA. The distance between main unit and hand-controller is up to 3 meters. The perfect solution would be to have individually shielded twisted pairs.

At the first, I was thinking about RJ45 connector and CAT cable, but I am not sure about current rating. In that case I would use one twisted pair for power supply and the rest of 3 for data transfer. It seems as not reliable option for powering. There is also combination of CAT cable with two additional power lines, but it would require two connectors, so not pretty elegant solution (prefer to stay within one connector). Additionally, I need robust connection as the hand-controller would not be stationary.

What do you suggest that could be suitable for my application? The connector size is not much important. I just need to be sure that I can find also the proper cable for such connector. It is also not important if it is not exactly the right fit (e.g. have 1-2 twisted pairs more than I need).

Thank you.


texts:
If we look at the output stage of the MP111 op-amp it's just 2 MOSFETs in series. I'm curious why the power dissipation of the device isn't simply \$R_{\text{ds(on)}} \times I_{\text{out}}\$, but rather \$I_{\text{out}} \times (\text{supply voltage} - \text{output voltage})\$

If we had a MOSFET in a box, the power dissipated by that 'box' would still just be \$R_{\text{ds(on)}} \times I_{\text{out}}\$ wouldn't it?

Datasheet: https://www.apexanalog.com/resources/products/mp111u.pdf


texts: Identify when the inverter is pumping energy back into the grid

texts:
Assume I have access to my solar panel inverter's voltage, current, and reactive power measurements, and these are taken every 5 minutes.

By inspecting this trace, how can I tell when my panel is feeding
energy back to the grid? Is there any other information I need to
know?
Can I also calculate how much energy is being pumped into the
grid? (Even a rough estimate will suffice.)

I do not have a background in power engineering, so I'd appreciate any responses that assume minimal knowledge of the domain. Thank you!


texts:
I was expecting I(R1) to be 8.15A
What did I do wrong?


texts: ESP-12F module "correct" wiring for usage as modem?

texts:
I have wired the ESP-12F module as shown in the diagram below.
I can not get reply when sending "AT" at 115,200 Baud 8bit, 1bit stop, no parity.

Is this the correct wiring?
Is there a special start-up sequence that might prevent the module from working properly if not followed?


texts: Replacing ceramic capacitors with film in PSU

texts:
Some Behringer Truth B2031 came back from a friend and they're acting up. first thing I noticed was the four .1uf ceramics that are in parrellel with the bridge rectifier diodes have experienced violent explosions, likely due to electrical storm. The highest voltage I can find for these locally is 50V, and the original ones were about twice the size physically so I'm assuming there were rated for higher voltages.

Even at Mouser, .1uf is the highest ceramics go and the selection is minimal with to +50V ones being expensive (I need 8 of them).

So, seeing as there are plenty of .1uf films rated for +500V for a fraction of the cost, can I use them instead?


texts: Switching between capacitors causing ringing

texts: I have a series resonant circuit where I have a fixed value inductor. I have few a capacitors which are connected to the inductor through some mechanical relays. I am changing the frequency and switching a particular capacitor from the capacitor bank for resonance. The relay I am using has a contact capacitance of 10pf. it doesn't happen always but sometimes when i am turning on multiple capacitors to see if the circuit reaches a better resonance there are sometimes some ringing. The frequency range I am using is from 500khz to around 2Mhz. in order to drive the series resonant circuit I am using a few cascaded op amps whose input comes from a function generator. I wanted to know is the ringing coming from the capacitors or is there a possibility that the op amps are oscillating. If its coming due to switching of capacitors can i damp the oscillations by connecting a large value reistor in parallel to each capacitos. I don't want to add high value resistor in series because that will reduce the current through the circuit.


texts:
I think the power for a CPU with current I and voltage U is I · U.

I wonder how the following conclusion from Wikipedia is derived?

  The power consumed by a CPU, is approximately proportional to CPU
  frequency, and to the square of the CPU voltage:

  P = CV2 f

  (where C is capacitance, f is frequency and V is voltage).


texts: Voltage between phases of 220V 3-Phase Generator with no neutral

texts:
I'm looking at a 220V-50Hz 3phase generator which has no neutral wire and 3 live wires.

Am I correct in assuming that the voltage between phases will be 220V for this generator?


texts: This circuit is being called a constant current source, how can this be? Since the gate and the source are both connected together their isn't a potential difference between them. Doesn't' this mean that the transistor should be off? Or do I have this confused with a BJT?


texts: Operation of Junction field effect transistor

texts: Is Vds necessay for Drain current (Id) or we can get Id by Vgs also as in books it is written that Vds is necessary.


texts: Why do I have to disconnect and reconnect the Microchip ICD3 after every programming?

texts:
I'm having a problem with the Microchip ICD3 programmer.

I'm getting connection problems, connecting to the programmer itself, even when using the selftest mode with the Microchip-provided selftest hardware board.

After plugging the ICD3 into my laptop, it always works the first time I run the selftest.

The second time, I get this error message:

"Could not connect to the selected hardware tool. Please make sure the tool is not being used by another project in MPLAB X."

If I unplug and replug the ICD3 to the laptop, it works again one more time.

I'm running Linux Mint Qiana. I've tried it in Windows 7, and there it works reliably every time. I've also tried it in Debian Jessie, and there it fails like in Linux Mint Qiana. I've also tried it on Redhat Fedora Core 22, and there the computer hangs at the end of the MPLabX install (screen goes black, computer becomes unresponsive).

I've been using MPLabX version v3.05 (I've tried it with version 2.x-something as well, but it fails in the same way with a slightly different error message).

So, the above eliminates the following causes:

My PIC program/PIC (since it isn't even involved)
My ICD3 hardware (since it works in Windows)

So the problem must be in my linux installation. I'm assuming Microchip, being a large and quality-minded company, must be testing their software before release. So I'm assuming the ICD3 worked at one time for a Microchip-employee. So my question is basically, what Linux distro were they using, and what differs between that and mine so that mine doesn't work?


texts: Dual (Shift Up and Shift Down) SPI Level Translation

texts:
I'm faced with an interesting challenge: I'm using a microcontroller with 3.3 V logic, but I need to use a SPI (4-wire) interface with parts operating at three logic levels, namely 1.8, 3.3, and 5 V. Obviously 3.3 V isn't a problem, but I'm curious about the best way to handle the 1.8 and 5 V components. Of course I could use two discrete level translator ICs, but I'm hoping there's a simpler (i.e. cheaper, smaller footprint) solution. I already have ways to generate the voltage supplies, so that isn't an issue.

I'm aware of the following MOSFET level translation technique, which I understand well enough:

This allows a 3.3 V signal from the µC (from the left) to shift up to 5 V to a certain device (to the right). (It would have to be backwards for MISO.) I could similarly change the voltage on the right to 1.8 V to shift down for a different device. Here is my issue: If I were to simply switch the voltage between 5 and 1.8 V, I would almost certainly destroy the 1.8 V pins when at 5 V. Is there an elegant technique for allowing a shift to two different levels, or will I have to suck it up and use two separate circuits for the two translations?


texts: Why is the output in a Moore Machine determined by the current state?

texts:
It makes sense to me that the output in a Mealy machine should be determined by the input and the current state because it gives me the feeling that it is really an output.

But the outputs in a Moore Machine are given by the current state, and this doesn't make sense to me at all. Why aren't they determined by the next state?

Sorry if my question is dumb.

Thanks.


texts: Can I run an Arduino off 8 x AA batteries? The documentation says it can run from 5-12v which is in the limits of the the specs.  I wanted to ensure I had more than enough power for anything else I wanted to drive through it.  Would it be better to run the Arduino off a 5v regulator from the 8 battery supply then draw anything else off the power supply directly?


texts: How to adjust the feed line of 3x3 patch array

texts: I stuck with some questions about 3x3 patch array. It's said that patch antenna frequently is 200 Ohm. Is it always? Ain't that change with antenna design parameters such as length? Do I have to consider each patch is 200 Ohm and design the feed lines in respect to 200 Ohm and at the end of the antenna, transform it to 50 Ohm which's I wanna feed the antenna with?


texts: Magnetic flux outside a solenoid perpendicular to the direction of axis of solenoid

texts:
I know that using straight forward Biot-Svart law it is possible to calculate field inside a solenoid or at a point on an axis away from the circular coil.
Now is it possible to calculate the Flux outside a solenoid (OFF AXIS) in direction perpendicular to the direction of axis of the solenoid ? I know it is much weaker outside but still can we deduce it mathematically ?


texts: Running a stepper motor at less than rated amps, what's the torque?

texts: I have a large round stepper I salvaged that is rated for 5A. If I drive it with a 2.5A driver, how will that affect the torque? Will it cut it in half? Is the effect even predictable at all?


texts: Why do we need 100nF cap in the output of an SMPS?

texts:
I was looking at Micrel AN-53 and I have noticed that in a circuit in the first page (circuit is below), at the output of an 400KHz, 27V, 7A, 180W boost converter, there are two 680 uF, two 10 uF and one 0.1 uF capacitor.

I can understand that 680uF capacitors are the bulk output capacitors and instead of 1360 uF, it is better to use 2x680 uF with the benefits of low ESR and rejection of higher frequencies than the ones rejected using 1360 uF.

I may understand that 10 uF is to smooth out even higher frequencies and they have much lower ESR than electrolytics.

However, I cannot understand why is 100nF capacitor is used? Load will use decoupling cap if needed. In addition to that, shouldn't the 100nF capacitor be placed very close to the supply and the ground to keep the lead inductance low? Won't the filtered signal get nasty on its way to the load? Using it in the output makes no sense but unnecessary and extra PCB area to me.

So, could you please explain the function and the need of 10uF and 100nF capacitors in the output (C3, C4, C10)?


texts:
When working with surface mount components with different pitches, or with mechanical dimensions on different grids, the situation inevitably occurs that you have two wires or lines that need to be connected, but neither are on the current grid - in fact they may not end up on any sensible grid.

As an example, here are two lines, neither on the routing grid, which must be connected together to form a right angle (or mitred join).

When these are traces being routed, it becomes fairly straight forward as the route tool allows for snapping to the ends of air-wires, so you can simply click on one end and then have the route snap at the other end.

However when such lines are not traces - such as silk screen lines or dimension lines, the snap doesn't work. You can CTRL+LeftClick on the end of the first line to start routing, but Eagle won't let you snap to the end of the second line.

You can also drag the ends of the lines so that they overlap, however there is no tool to intersect two lines unless the end of one lands exactly on the other.

The question arises as to what the simplest way of joining these wires?


texts: I recently ordered a 50 pack of relays on sale for 5 dollars at electronic goldmine. They have 9 pins each and they are labled rk1-24v Ark112 910 25m. I know that they require 24 volts but I can't figure out where the coil is and where the connections like NO and NC are, nor can I find a datasheet that tells me this. I tried hooking up 24 volts to different pins, but I heard no click. So how can I find the right pins to hook the relays up?


texts: Is Vout in this circuit loop-grounded when Vin becomes 0V?

texts:
I don't have expertise in this area.
So any answer or instruction would be helpful to relieve my pain.

I think Vout would lose its GND when Vin becomes '0V' because C is located before GND.
Am I right? or wrong?


texts: Could anybody help to identify this connector type? I know it is kind of old.


texts: What does an eigenvalue tell us about the system?

texts:
I have an electrical system to be controlled (Cuk converter). So I get the space-state model given by:
$$
\dot{x}(t)=Ax(t)+Bu(t)
$$

If I determine the eigenvalues (of the matrix A) I obtain: $${-113.654 + 482.816 j, -113.654 - 482.816 j, -85.204 +
  174.817 j, -85.204 - 174.817 j}$$
with \$j\$ as the imaginary unit.

So, can I tell something about the system from these eigenvalues? Like, can I predict the order of the unit-response or impulse response? Does it mean something that the eigenvalues are complex and conjugated?


texts: Combine Lower Gauge Wire to Achieve Thicker Gauge

texts:
I have, for some reason, a ton of 30 AWG wire lying around. It's not really thick enough for a lot of applications. Would it be acceptable (and safe) to combine multiple strands of the wire and just join the ends to make one thicker conductor?

In case that it matters: I'm thinking about adding a relay to a light switch so that an Arduino controller can detect when the light switch is on. The light switch is on 120 volt mains power and must still turn the light on and off.


texts:
I like to detect current passing through a wire. I have only a very small opening (15-20mm diameter) that access to wire so using a current transformer is not feasible. I can touch the bare wire. (I can touch with a tip of a scope probe) The wire carries 1 - 10A and 220V. I am looking for a non-contact or contact way of understanding the current passing through. 10% accuracy is good enough.

Any pointers?


texts: Servicing mechanical selector switches / rotary encoders

texts:
After 15 years of use, one of my Alps mechanical selector switches (metal contact spring dragging across metal tracks) had developed oxidised/dirty contacts.

After some cleaning with alcohol and Kontakt 60 the contacts are once more shiny and the switch is ready to be reassembled. - Just one last issue: should the contact spring which drags across the contact tracks be lubricated or protected against moisture?

If yes, using what? Silicone oil/grease, WD 40, watchmaker's oil? Or is keeping everything dry and clean best?


texts:
I am planning to build a software defined radio. For this purpose, I need to sample analog signals using an analog to digital converter. In clasical Nyquist sampling, we need to sample with a rate \$f_s>2f_{min}\$ as we all know. But what I want is not to Nyquist sample but to band-pass sample. For example, I need to sample a signal with 1 GHz center frequency and 10 kHz bandwidth. My question is can I use MCP3002 adc with following analog input model to undersample example case.
http://www.imageupload.co.uk/images/2014/03/03/analoginmcp3002.jpg


texts: How to sense a small current while handling larger ones

texts:
For one of the projects I'm working on, I need to monitor a DC power line for reverse current; the solution has to output a 24V signal when around 10A or more of current is flowing in reverse through the line (forwards current can be ignored), but the line may carry up to 400A in either direction.

The main problem seems to be that for any solution, say a shunt resistor with a sense line connected to the gate of a MOSFET, anything that will give a workable output with 10A going through the line would fry at 400A, while anything that works at 400A would give a near negligible output at 10. In general, how does one usually measure something that could range much higher than the target measurement value?

For this specific application, we would love to just use something off the shelf, but the general question is something that seems handy to know.


texts: Reference to understand LED data sheet specification, characteristic and way to use them

texts:
I'm trying to build my own IR-led light with multiple LEDs. I've bought a TSAL6100 IR led but I'm not sure how to interpret the data sheet, I can't find any reference in internet. Can anybody tell me where I can find the informations or interpret these parameters and tell me how to use them?

I'm an "hobbist"!

I would like to know the difference between basic characteristics and absolute maximum ratings, which one of these contains the information for the normal usage?

EDIT:
What does it means TYP column? Typical usage or is a mean in case of voltage drops? Why I_F in Absolute maximum rating is 100 mA but in basic characteristics is 1 A with pulsed? Why even for 100 mA the t_p is 20 ms so I should use this led only in pulsed?


texts: High bulk capacitance (100.000 uF) discharge time on Wifi router supply

texts:
I want a WiFi router, those supplied with 12V x 1~1.5A AC-DC wall adapter, to remain ON for a short time (maybe one second or a little more) after the AC mains gets its energy interrupted, when AC goes down.

One idea is to place 10x electrolytic caps of 10.000uF x 16V on the 12V output out the adapter (supply input of WiFi router), a nominal 100.000uF capacitance.

Is there a way to "have an idea" of the number of seconds the routers can remain ON after the AC goes down? And also for Wifi routers with integrated modem.


texts: Is there a circuit (that only uses op-amp and resistors) that performs multiplication between two DC input signals v1 and v2? Similar to the Summing Amplifier but with multiplication.


texts: Using USB-RS232 adaptor for USB-TTL connection?

texts:
Seems there are plenty of questions relating going in the opposite direction, but I couldn't find anything that really told me if I could do this..
I have one of these https://uk.rs-online.com/web/p/serial-converters-extenders/6877806/ for connecting to RS232 devices and I have a need to connect to a device using a USB-TTL adaptor (one of these https://www.dimensionengineering.com/products/sabertooth2x60)
It seems that the Sabertooth only uses RX, TX and GND (pins 2,3, and 5) and I don't need any of the other wires. I'm not 100% sure on what voltage sits on pins 2 and 3 of an RS232 connector - I assume if it were more than 5v then that wouldn't be ideal for TTL!
Can anyone give me a pointer as to whether this will work or not? I don't have a reason to not buy a specific TTL adaptor, apart from I'd rather not do it if I don't have to!
Thanks in advance


texts:
My goal is to have an LED flash (rather than stay on all of the time) in order to conserve battery life. So, I learned how to modify a 555 timer circuit so that the LED flashes for about 0.1Hz and remains off for ~10 seconds.

The circuit diagram is like this:

Source:  http://www.electronics-tutorials.ws/waveforms/tim58.gif?81223b

Are there other components in a 555 time circuit (resistors, capacitors, 555 itself, etc) that are drawing energy and will significantly affect my battery life, even though I have greatly reduced the duty cycle?


texts:
Answers to other questions here (e.g. 1) show capacitors used to drop AC voltages to levels suitable for a LED. I've seen much simpler circuits such as the one below

simulate this circuit – Schematic created using CircuitLab

Assuming it's in a suitable enclosure, are there significant drawbacks or dangers to this circuit compared to others?


texts: Operational amplifier - why average voltage is not stright related to pulse to duty cycle?

texts:
I have a strange problem, that I cant find an answer.
I have slow photodiode (about 2MHz) and fast, pulsed laser light source (pulses 10 to 500ns). Im trying to measure optical output power. To do it Im using operational amplifier and low pass filter.
Pulses parameters: frequency 10kHz, pulse time 500ns.
Here is my LT spice circuit.

And here is a chart

I thought that after low pass filter should be directly linear to duty cycle. So for 10kHz, and 500ns pulse duration I have amplitude for ex 0,6V, so for the same frequency but pulse duration 250ns (half of previous duration), amplitude will be 0,3V. But there in fact it is about 0,37V.
Here is example table for 100-700ns pulses, and amplitude.

Im really confused what is going on.
EDIT:
I was not clear. Simulation works great, and as brhans said there is an offset. But im really confused about real circuit, that Ihave made. And there is some non linearity.


texts: Circuit design: detecting oscillating magnetic fields with pick-up coil, amplifier, filter

texts:
I'm struggling with this circuit design problem quite a bit. It's for an experimental physics course, where the professor is sampling a number of different topics to lecture on. Unfortunately, he didn't lecture so much about circuits as give us "The Art of Electronics" and say good luck...

Anyway, the problem is that we wish to detect electrical interference from 60 Hz sources using "a pick-up coil and an amplifier with a filter to pick out only signals near 60 Hz".

The set-up is as follows: we have a circular coil, radius 1 cm, with 10 turns of wire. We need to design a circuit which takes the output of the coil and gives a signal on an oscilloscope, calibrated to \$1 \text{ V}/\mu \text{T}\$. We assume that there is a magnetic field orthogonal to the coil with field given by
$$ B = B_0 \cos(2\pi (60 \text{ Hz}) t), $$
and assume that the input impedance is 1 MΩ. We are required to use OP27 operational amplifiers and to provide values for all resistors and capacitors we use.

My attempt

I began by computing the voltage induced in the coil by the magnetic field. The flux through the coil will be
$$ \phi = \pi r^2 B_0 \cos(\omega t) $$
where I'm letting \$ \omega = 2\pi (60 \text{ Hz}) \$. Then the voltage induced will be
$$ V_{in} = - N \frac{d \phi}{dt} = N\pi r^2 B_0 \omega \sin(\omega t).$$

At this point, I'm not really sure how to proceed with the filter. I decided to just try to use an amplifier to calibrate the outgoing signal as desired, so I chose to use a non-inverting amplifier. This would adjust the outgoing voltage to
$$ V_{out} = V_{in} \left( 1 + \frac{R_1}{R_2} \right) $$
for two resistors with resistances \$R_1\$ and \$R_2\$. I've also found notes which say that because the oscilloscope's input impedance is so high, we can assume the signal will be unaffected. As such, we can set \$V_{out} = (1 \text{ V}/\mu\text{T}) B\$ and solve for the ratio of \$R_1/R_2\$ that solves properly calibrates the signal, no?

Honestly, I'm not sure that the above is very correct, and I really don't have any idea how to filter out signals far from 60 Hz. Would anyone be able to offer any guidance? Even just pointers to other books, papers, online lectures, etc.? I am really struggling to find much, so any help would be greatly appreciated!


texts:
I am designing a system with the ADS4245.
My requirement being a 14bit,dual channel I/P and a max of 125MSPS. I understand that going higher without the capabilty to program or select an output sampling rate would be a disaster. Hence-forth I went with the ADS4245.
With the requisite parameters are entered, the TI website recommends the ADS4245
But, the data sheet shows the output as LVDS.
How can then this serve my purpose please ?
I am attaching the image of that chip (and the LVDS info). Wouldnt LVDS be useless as in effect it is a 7bit differential output where as I am needing 14 bit output.

What is the difference between a normal 14bit ADC output and an LVDS output ?
I merely wanted to confirm that this would be of no use to me due to its LVDS capability.


texts:
I'm currently working in a project where I need to control the intensity of 24 high power LEDs in 5 levels.
I'm planning to use LumiLeds L1CU-BLU1000000000 (https://www.lumileds.com/uploads/705/PB198-pdf) where the cut-off voltage is 2.83 volts and current is 350mA.
As per the requirements, the power supply should be from an SMPS ( maximum output - 12v,6A).

I need to select a constant current driver with PWM facility ( 0-5v max ) to control the LED intensity from a micro-controller.
What type of driver IC will be best suit for this application?

What I know so far is:

I can use a constant current boost converter IC with PWM ( input-12v,3A max and output 23v,1.3A) and connect 8 leds in series and 3 such strips in parallel so that each parallel branch would get around 350mA and each LED in the strip would get around 2.8V. In this case I need only one PWM channel from micro-controller to dim all LEDs at a time. If someone could suggest a driver IC for this specification it would be great.Are there any hidden flaws in this Idea or is it less efficient in terms of power consumption?
I can use a constant current buck converter IC with PWM ( input 12V, 3A max and output 9.5V,2.8A) and connect 3 LEDs in series and 8 such parallel strips.
Each series strip gets around 350mA and each LED gets around 2.8v (with some resistors added to each series branch)

If I'm using 3 driver ICs and dividing up the LED load among those, is it still okay to use 3 pwm channels from the microcontroller for dimming all the LEDs simultaniously?

I've googled a bit and found these ICs, but confused in selecting the best one for the job.

STCS2A (https://www.st.com/resource/en/datasheet/stcs2a.pdf)
MAX16834(https://datasheets.maximintegrated.com/en/ds/MAX16834.pdf)
LuxDrive 3021-D-I-1000 (http://www.luxdrive.com/content/3021-BuckPuck.pdf)

Please do suggest me a good design method and suitable driver IC.


texts: I have been playing with the board shape, im planning to send this to OSH spark for manufacturing, however i have doubts about if they can do cutoffs of the boards like this or any other possible form i desire, or should i just stick to square shaped pcbs?


texts: Repeated dimmer switch fault following bulbs reaching end-of-life

texts:
I have a dual 1-way dimmer switch, 240V rated for 40W-400W, to which one of the dimmers has 5 x 60W dimmable bulbs (ceiling lights) and always works without any issue, and the other dimmer has 4 x 28W dimmable bulbs (wall sconces) with which we are regularly having trouble.

Every time a sconce bulb goes pop, the circuit breaker trips and the associated dimmer dies while the other dimmer on the switch continues to work. We've had this not just on this particular lightswitch installation but also on another in the same property where once again wall sconce bulbs popping kills the associated dimmer.

Is this a common issue? At first I wondered whether with bulbs pointing upwards maybe if the filament dropped into the base it would cause a short-circuit and these problems might result, however I get the same issue with Halogen eco bulbs aswell.

Having had to replace these switches around 6 times now its getting a little rediculous. Any ideas what would cause this? If I change the wall scones would that make a difference do you think? Could it just be poor quality switches (typically £15, tried 3 different brands so far).


texts: Op-Amp inputs are sinking too much current in comparator mode

texts:
So I basically designed a circuit to limit the current flowing through a 250 ohm resistor by shutting down the current path using a mosfet when current goes above 30 ma:

R1 is the 250 ohm resistor that needs to be protected from over-current.

R4 and R6 create a voltage of 7.5 voltage for the comparator

R5 and R3 limit the voltage falling on mosfet gate to 10 volts.

if more than 30 ma pass through R1, the generated voltage will go above 7.5 volt and the op-Amp output will become zero shutting down the mosfet.

I have a slight problem. When v1 (is equal to zero volts) the currents of negative and positive op-amp inputs are +/-2.5 ma.

If I increase v1 to 4 volts, aforementioned currents reduce to 1 ma.

At v1 = 10 volts, they reduce to 250ua.

These values are too high. According to the datasheet of the op-amp, the input bias and offset currents shouldn't have exceeded 1.5na.

What am I doing wrong? What is the problem here?

In fact the output of the op-amp never becomes zero and R4 and R6 never create the 7.5 volt reference for the comparator. The voltage is always lower even going down to about 3 volts when v1 =0.

P.S. Simulations are performed using LTSpice.


texts: How to connect INA321 in order to measure current across a resistor?

texts:
I need to measure control over a resistor using an  instrumentation amplifier.

I am using INA321 but for some reason, it does not work.

Here is my circuit:

In this circuit, the output voltage is Vout=(V1/R)RG
but for some reason, I get a different answer. What is wrong with my circuit?

I added the INA321 datasheet

INA321_datasheet

Here I used a shunt resistor:


texts:
I have done thevenin analysis on a larger circuit and have gotten the result below. I need to find the value of RL.

Would I use thevenin again? But that would give me the same result because I would be finding the same V-open and R-thevenin again.  My short circuit current was 2mA, but I'm not sure if that applies anymore if I reduced it to this form below.
Can you clarify this for me?

simulate this circuit – Schematic created using CircuitLab

from my lecture slides:

The task is to select RL to maximize the power transfer from source to load. (as found out by @Null in the comments)


texts: What is this solid state starting relay component?

texts:
My refrigerator died, most likely because of the starting relay+capacitor assembly which I already replaced once a few years ago. The parts store is closed today so I was curious and took the whole thing apart to find out exactly what broke down as this was sold as a "solid state" replacement, for which I find the lifespan rather short.

There is an obvious large capacitor, what looks like an overload protection and a third component which I presume must be the relay from the way it is wired. What leaves me puzzled is that it only has two connectors and is wired in series with the capacitor. What I've found online suggests the classic component here is a "potential relay" and should have a third connection. But this does not.

So of course I broke it open. I am including pictures of what I found: a mysterious circular disk (the component I'd like identified) sandwiched between two metal plates with springy contact points.

The dirty side of the disk was in contact with the dirty plate. The disk has 40 ohms between the two sides, where clean. The dirty part appears non conductive and is, I suspect, why whe whole thing stopped working. Before being broken apart, the sandwich was a little loose and I could press the components closer together with my fingers. It seemed made so one side of the sandwich could slide. The case was typical electrical component plastic, similar to what the back of a wall outlet is made of.

So the question is: what is the disk and how does it make this thing into a relay or equivalent?


texts:
I am trying to build a project with ESP8266. To save PCB space and avoid complexity I have chosen to use Hi-Link's SMPS module for 220V AC- 5V DC conversion. I am bad when it comes to noise / frequency. I have used a 22uF/16V tantalum and a 100nf/6.3V ceramic to deal with the ripples. Below is the schematic. Here is the SMPS module I am referring to http://www.hlktech.net/product_detail.php?ProId=60

C1 and C3 will be close to ESP8266. What I need is a clear and more importantly stable power for the cheap. High ripple may damage the cheap. As this is not an audio circuit, I believe a little noise would be OK. Please suggest.

Am I good with this setup?


texts:
I've read a lot about FSMs (Finite State Machines) when doing VHDL tutorials. They are easy and I've used them a lot but I still don't understand something and can't find the answer online:

When should I use FSMs (Moore or Mealy) in my VHDL design?

For example, if I implement an algorithm (previously in C language) in VHDL, shall I use an FSM?


texts: How to compute the resistance and voltage of this schematic?

texts:
I have the following diagram I've set up in a simulator:

However I have no idea how they get 3.75V at that point (the upper left spot is a voltage reader) nor do I really even know how to apply Ohm's Law for series and parallel resistors because things are sort of joining at corners and I can't easily just pick two and say "these are in series" or "these are in parallel" because there's other "stuff" in between them. How do I wrap my head around this better?


texts:
I was reading the 10th edition of "Operating System Concepts" written by Abraham Silberschatz and many others. It says about IA-32 architecture's segmentation:

  The IA-32 architecture allows a segment to be as large as 4 GB, and the maximum number of segments per process is 16 K.

but I don't understand, we need 14 bits to determine the segment and the CPU is 32 bit so 18 bits left, Therefore the maximum accessing area is 256KB, not 4GB. Help me understand how we could manage 4GB here.


texts: From where to  download the tsmc model file for nmos(slow,fast,typical) and pmos (slow,fast,typical)?


texts: How to increase the current in this circuit?

texts:
Im trying to build a circuit to send information using IR led, using pulse signals (Im trying to mimic a home appliance remote control).

My leds (datasheet) operate at 1.3V, and their maximum pulse current is rated 200mA

I need a very strong signal and since the "commands" I send are quite short, I understand that there's not much harm in operating it at higher currents.

I tried to use two IR leds in series, aiming to 300~mA current flow trough the leds.

I did the following calculation:

Vs = 5V
I = 300mA
Vdrop of each led = 1.3V
so R = 5v - 2.6v / 0.300A.

I managed to build 22Ohm || 10Ohm = 7~ Ohm
Im controlling the base of my BJT 2N2222A transistor using my controller gpio, which is rated at 3.3V.
In reality, I measured 80mA, which isn't what I expected.
I expected it to be in saturation, since:

Vb = 3.3V
Vc = 0V
Ve = 0
Ve < Vb > Vc => Sat.

simulate this circuit – Schematic created using CircuitLab

What am I doing wrong here?


texts:
I am trying to programme a PIC, but mplab_ipe will not recognise the programmer (the tool list is not populated), nor does running sudo dmesg . The programmer has 01.30.09 PIC18F firmware.

Any help appreciated


texts:
I find some text about the winding of a toroid core as below:

But what's the math and physics behind these?

BTW: Can someone suggest some good books about the design of an inductor/transformer not only in theory but also about "how to make them by hand".


texts:
After introducing the two-stages op-amp and frequency compensation for this circuit,  during lecture the Professor asked us to find as an exercise a possible polarization of the following circuit:

in which by hypothesis Vdd=1.8V and the input dc common mode is 0.9V.
While solving together this exercise, the Professor said that, in order to use this circuit in the unity gain buffer configuration, the output dc voltage must be set equal to 0.9V. In this way the input dc common mode coincides with the output dc voltage, as required by the unity gain buffer configuration.
Question: why do I have to "artificially" impose that the output dc voltage is equal to the input dc common mode in order to have unity gain buffer configuration? Is not the negative feedback which imposes Vout=Vin?


texts: How to resolve this :Arduino UNO not working with Arduino wifi shield?

texts:
I'm having a lot of issues regarding interfacing an Arduino wifi shield with the Arduino Uno. My Arduino works fine when the shield is not attached to it but when I attach the shield, I'm unable to upload the code; I get:

avrdude: stk500_getsync(): not in sync: resp=0x00

I also tried to change my board and uploading the code on Arduino due, then it gives:

device not found on COM 8 as error

Otherwise the boards are perfectly fine, they are working usually they should. Also, I'm unable to reset the board when the shield is mounted on the board.

This is the shield I'm using which is the usual Arduino's official shield:

These are the things i have already tried but none is working :

powered up the arduino from external power supply (12 V, 1A)
removed the shield and programmed it (code loads on board ) but then mounting shield on board, the led on pin 13 cease to blink
without using the shield , arduino works as usual (like that Rx, Tx pins work and pin 13's LED and power led  blinks /lit up) but with the shield stacked on board , nothing seems to work


texts: discharge of capacitor through a current source

texts:
Assume we have a cap connected to a current source that draws a current \$I_0\$. What time would it take to discharge the cap by a voltage \$V_t\$?

$$t=\frac{C \times V_t}{I_0}$$

Is this correct or am I wrong?


texts: Trinket M0 PWM ValueError: duty_cycle must be between 0 and 65535 inclusive (16 bit resolution)

texts:
I'm trying to control a servo motor from a Trinket M0. My circuitpython code is:
import time
import board
import pulseio
from adafruit_motor import servo
pwm = pulseio.PWMOut(board.A4, duty_cycle=2 ** 15, frequency=1000)
my_servo = servo.Servo(pwm)
my_servo.angle = 180

But I get a ValueError saying that "PWM duty_cycle must be between 0 and 65535 inclusive (16 bit resolution)."
Full disclosure: this used to work but I accidentally short circuited my wiring by connecting the control wire of the servo to the reset pin of the Trinket M0. Is it possible that this would have damaged the SAMD21 on the M0?


texts: How to wire pull-down/up on an N or P channel MOSFET?

texts:
In case I'm switching a 24v signal and using a MOSFET as relay and a 5v signal to gate.

How and where I should place a PullUp or PullDown on drain or source to ensure a stable reference in case MOSFET is open? I.E. If my MOSFET drive a PLC I/O


texts: Approximation of a Non Ideal Differentiator

texts:
simulate this circuit – Schematic created using CircuitLab

The above circuit is a differentiator, the op amp is assumed to be a single pole op amp, that is \$ A=\frac{wt}{s}\$

The transfer function is thus going to be that of a band pass filter. (2nd order)

My question though is, this is also a differentiator, so upto what frequency can this be approximated to be a differentiator.

Had it been an ideal op amp, it'd simply be a high pass filter. Now that we consider it to be non-ideal there must be a certain frequency upto which it can act as a differentiator, however, I have no idea on how to calculate that. Maybe using Phase/Magnitude errors?


texts: Microcontroller maximum and minimum source and sink current

texts:
I'm using the S32K142 64-pin microcontroller.
I have a question about this table:

What parameter does the maximum sink current and source current depend upon?
The marked line in the table says that if the current sourced by the pin is 3.5mA, then the voltage on the pin is 3.3V-0.8V = 2.5V with respect to ground for a 3.3V supply voltage.
If that's the case, on what parameter does the minimum and maximum sourcing and sinking current of a GPIO depend?


texts:
I want to connect an old phone to a Bluetooth module. I first thought to use the original speaker and microphone, but the quality is quite bad, so I decided to rip apart an old PC-microphone and cheap headphones.

The microphone is a simple electret condenser, the headphone speaker (don't know exact model) is two-wire and measures 31 ohm, and I use the BTM510 Bluetooth module. The Bluetooth datasheet states that it can drive speakers with a minimum impedance of 16 ohm directly.

The problem is that the old phone horn uses a common ground for the (original) speaker and microphone, so there are only three wires running up the cord. From what I found on the internet, not all amplifiers can have their audio- connected to ground, but I would really like to keep the original three-wire cord.

Is it possible to connect the speaker and microphone to the module with the speaker negative side connected to ground, like in the following manner (with Vcc being about 3.8V). Would this work properly? Would I loose half the power of the speaker?


texts: Calculating current draw from a battery using voltage and time information

texts:
Is it possible to work out the current or power a device is drawing/using, based on the following information:

Maximum capacity of a battery (48 Ah)
A table of voltage readings over time (starting at ~13v ending at ~11v over a period of 40 days, sampled every day at 2pm, ignoring the end part of the test where the battery voltage drops off non-linearly)

I am doing this to try and estimate how long the device would work on batteries of different capacities to the one tested, and I have a feeling it's not as simple as just dividing the battery's rated ampre-hours by the number of days it lasted and extrapolating...!

Thanks in advance for your help.


texts: Protoboard/Veroboard alternative for huge LED sign?

texts:
I'm preparing for a project which is an LED sign, it will be an LED matrix, but only have the necessary LEDs attached so it will only display one "word" but each individual LED of the WORD can be controlled for nice patterns etc.

In the image below tracks run horizontally. As can be seen, a single LED obscures 3 holes in its width, and one space must be left above each LED.

Ignore tracks in the image above, it's merely to show spacing and not electronic contact.

Now I have received my LEDs and measured properly, the real dimensions I require are as follows:
114 LEDs wide, 28 LEDs high

342 Holes wide (min)
84 Strips high (min)
80cm wide (approximately calculated minimum)
23cm high (approximately calculated minimum)

The board doesn't have to be copper type vero/proto/matrix, it can be plain, but I need something that will rigidly hold the LEDs evenly spread so I can wire them up how I need off the board if necessary. It doesn't have to be one piece, but I do want to achieve even spacing, cost is an important factor in the choice.


texts:
Ddesoldering a capacitor: On board we have a power supply unit requiring replacing capacitors 1000uF 50V. Although its showing 0v (i.e. have been discharges and unit has been isolated from the main board but still capacitor joint does not meelt. I also used wick flux wire to to desolder. Do I need higher temp? I have 40W iron that normally works fine.
Any ideas?


texts: MOSFET burn down due to droping logic level voltage

texts:
I made 2 PCB, one is a logic driver with NAND  Schmitt trigger (74HC132D & CD40106B) to drive FORWARD and BACKWARD of H-bridge channel, the other board is the H-bridge Power MOSFET, which used 4 P & 4 N type MOSFET (paralleled), I might add P type MOSFET drived by pull-push circuit for enhance fast switching, following is the schematic and its images

NAND shield alone, work fine with Arduino and put the FORWARD and BACKWARD pins of MOSFET shield in opposite logic level (5 volt), but when I attached the MOSFET shield, that logic level drop to 2 volt, it seems input impedance of CD40106B inverters  is so low to drive MOSFET gate and thus MOSFET didn't turn on, then I increased the MOSFET pull down gate resistor form 1k to 3.6K but it burn my MOSFET, it seems slightly change in logic level voltage from 2 to 2.4 put the MOSFET in conduct mode with high Rds, I did some voltage measurement by multimeter (red number in schematic image) that shows Vgs not enough for conducting the  MOSFET.
My question is how to find a responsible component for droping the logic level voltage?


texts: How do current and voltage relate in a power supply in extreme conditions?

texts:
Theoretical question:

Say you have a power generator that can supply 1W at 100V DC.

If you connect a 10k Ohm resistor, exactly 0.01 A is going to flow across the resistor.

If you connect a 1 Ohm resistor, 100 A should flow across it, however the generator is limited to supply 1W, making it impossible. In this case, how much current is going to flow through the resistor? And what voltage will be applied?

My hypothesis is that, since power (energy) is conserved:

R * I^2 = 1 W

therefore I = 1 A. This implies a voltage of 1 V which means that the voltage applied has dropped from 100V to 1V. By the way, how quick is this drop?

Is this reasoning (and is result) correct?


texts:
I'm thinking about the design of an AM receiver frontend that needs to select between three channels. The community suggested that I investigate manually wound loop antennas, and they seem like a nice choice.

AM loop antennas are designed for resonance at a tuned frequency within a range allowed by a variable cap. The loop is inductive, so at the tuned station the loop and the cap resonate.

For my application, a cap with a wide range is not a good idea. I'd prefer to have three individually tunable sections that can retain their tuning, to be switched digitally. A circuit diagram follows (limited by my poor tablet software):

The sections are tunable around 3.33, 7.85 and 14.67 MHz, respectively. In each of the three tuning sections, the first cap is variable and the second one is fixed. The trim caps are 3-10, 4.5-20, and 8-45 pF, respectively. Once the trim caps are tuned they shouldn't have to change (much), barring aging components, mechanical antenna distortion, etc.

The switches are digitally controlled RF switches. An SP3T switch or individual switches are possible.

Is this a reasonable approach? For the RF switches can I use a topology similar to a digital pass gate with parallel NPN and PNP RF transistors?


texts:
Background
I am using FT232H to communicate with my peripheral using the libMPSSE provided by FTDI. I am aware of the INFRA_SLEEP(2) issue with SPI_ToggleCS() function. My peripheral requires me to send in a CS toggle right after each 24-bits of data being sent to it. I have 40 such words of 24-bits that needs to be sent to the peripheral.
I require to update the 40 words at a rate of 4KHz, which means I need to send 40x24-bit words every 0.25 milliseconds. This implies:

I need to toggle the CS pin 40 times every 0.25ms => 160/ms => 160,000 toggle/second.
I need to send 40x24-bit data every 0.25ms => 960bits/0.25ms => 3840bits/ms => 3.84 Mbits/second.

3.84 MHz (SPI) is the theoretical sustained minimum requirement for my use case. Since 1Mbit/sec => 1MHz in SPI and the theoretical max of FT232H is 30MHz, I need about 12% of the limits of FT232H. I technically don't need sustained 3.84 Mhz, I can zoom at 30Mhz, sleep for 0.25ms (up to), and then go at 30Mhz, is this not possible with FT232H?
Implementation
In order to overcome the SPI_ToggleCS()'s sleep issues, I have packed the data efficiently to FT_Channel_Write directly. All the commands are right, I inspected the FT_Channel_Write calls and captured the transactions to effectively come up with what to send to FT_Channel_Write. This part works. My pack size to FT_Channel_Write is 40x writes, which includes 24bits of payload and 40 CS toggles in that. Then my main loop sleeps for 0.250ms before waking up and sending the next payload.

Problem
After sending roughly 3150 K-bits of data via SPI no matter how fast or slow I send it, the FT232H seems to stall (no further data is sent till restarting my code). I have sent in different packet sizes, different delays, and a lot of combinations but. This seems to be the magical number I am hitting. 3135K to 3157 K-bits. Maybe there is some variance from testing.
Questions

What could be the issue here?
Is there a buffer size limit I should be aware of? (I did pour over the datasheet and couldn't find anything around this number)
What approaches would you suggest that I take to try to debug and find the root cause of this issue?


texts:
TLDR: The specific ordering question I'm asking is:

Suppose the output depends on some intermediate signals
Suppose the intermediate signals depend on some input signals
Suppose an input signal changes
This may make more than one intermediate signal change
The timing of signal assignment is not stringently specified
If the output signal generation function observes one of the intermediate signals as having changed before the other intermediate signals having changed, a "transient" output may be generated until the change in the second intermediate signal is observed.
Does VHDL guarantee that this does not happen? If so, how?

Reading through the Free Range VHDL book, on page 37, there is a code snippet that is claimed to be equivalent to the code snippet on page 36:

-- library declaration
library IEEE;
use IEEE.std_logic_1164.all;
-- entity
entity my_ckt_f3 is
port ( L,M,N : in std_logic;
F3 : out std_logic);
end my_ckt_f3;
-- architecture
architecture f3_2 of my_ckt_f3 is
begin
F3<=((NOT L)AND(NOT M)AND N)OR(L AND M);
end f3_2;

versus:

-- library declaration
library IEEE;
use IEEE.std_logic_1164.all;
-- entity
entity my_ckt_f3 is
port ( L,M,N : in std_logic;
F3 : out std_logic);
end my_ckt_f3;
-- architecture
architecture f3_1 of my_ckt_f3 is
signal A1, A2 : std_logic; -- intermediate signals
begin
A1 <= ((NOT L) AND (NOT M) AND N);
A2 <= L AND M;
F3 <= A1 OR A2;
end f3_1;

But! The description in the text claims that signals are delayed assignment ("some time" after) and timing or ordering is not guaranteed.

In my mind, this translates to approximately something like "the right side is sampled on clock-rising, and the left side is written on clock-falling," although I'm sure different implementations are actually used in reality.

Now, assuming that each <= operator in a logic chain introduces a time delay of undetermined amount, why are these two snippets equivalent? Couldn't it be that the second implementation, with temporary signals, temporarily outputs some logic value that is not actually the result of any combination of the inputs that it has seen?

I guess I'd like a more formal understanding of what the "signal assignment" really means for timing and outputs. Are compilers guaranteed to "optimize" or "short circuit" temporary signal assignments so that the end result will always be the same as if I wrote the logic expression on a single line?


texts: Controlling 1000W LED strips with Arduino using PWM and MOSFETs

texts:
I'm doing a large photostudio automated lighting setup and I'll need a lot of light so it will be 1000W of LED strips and I need them to be controlled by Arduino.
The strips are gonna be on about 20% of power most of the time and then for a photo capture (about 2sec) they gonna light up to 80-100%.
I have some electrical skills and I've done this before in smaller scales but I'm worried about controlling 1000W with PWM. So please can anyone confirm if following setup will work?

Power supply: 1000W 24V Mean Well (RSP-1000-24)
Arduino Uno with 6 PWM outputs
MOSFET modules from Ebay:

https://www.ebay.com/itm/MOSFET-Switch-Module-Four-Channel-4-Route-MOSFET-Button-IRF540-V2-0-For-Arduino/122680439778

https://www.ebay.com/itm/3D-Printer-hotbed-MOSFET-expansion-module-inc-2pin-lead-Anet-A8-A6-A2-Black-H5M9/253328731753

I need to drive 5 channels. 4 of them with 3Amps each and one channel with up to 30Amps. This channel can be split into multiple channels driven by single Arduino pin.
So I would use that 4 channel module for those 3A channels and then use two of those 3D printer powerful MOSFETs to drive that 30A channel split to two 15A channels.

Question 1: Will it work? :)

Question 2: Will the power supply be OK with driving the whole load with PWM? Are the PWM outputs from Arduino synchronized? Because if they are the power supply will be switching between 40A and 0A constantly. If I could offset phase-shift the PWM outputs the load for the power supply would be more spread. This is what I mean:

Question 3: The MOSFETs - will that 3D printer MOSFET switch at 5V from Arduino? Do I need some extra cooling? I think I should be OK, because the PWM load should be at 20% most of the time and then just about 2sec of full load. Right? Oh and is it a good idea to put multiple MOSFETs in series paralel  to spread the load - will it spread evenly? I guess better option is to split them into multiple channels right?
Thank you.


texts: Is there any way to check if a power supply is auto switching multi-voltage input (120-230VAC) with an output of 6VDC? The supply is an electronic power supply (not transformer based) but has absolutely no information on it. I do not want to fry it by trying 230VAC, as it does work on 120VAC. Thanks.


texts: How to achieve constant current for LED when voltage is variable in MCU

texts:
I am using STM8S003F3 to drive 1 RGB LED. Link of RGB LED :-  http://in.element14.com/broadcom-limited/asmb-mtb1-0a3a2/led-hb-rgb-0-09w-plcc-4/dp/2401106

To power the microcontroller and LED I am using Lithium polymer battery whose specs are 3.7V and 300mAh.

The voltage at full charge is 4.2V and it starts dropping with discharge percentage and drains at around 3.1V. The input voltage at MCU will drop correspondingly and the output voltage at the GPIO will also drop.

Value of Limiting resistor for LED at 4.2V.

R = (4.2-3.1)/0.02 (20mA)
  = 55 ohm

When the battery discharge the voltage will drop, then the current going through LED will be less, hence it will get less brighter.

At 3.3v

I = (3.3-3.1)/55
  = 3.6 mA

The led will not be visible and will be dull.

How to maintain constant brightness (i.e 20mA) even with drop in voltage?

One Solution is to use LDO which will maintain constant voltage and hence the current will be stable. But as I have very less space in circuit and due BOM cost, I am hesitant to use LDO.


texts:
This might be a dumb question, but with a circuit like this one:

Are we allowed to add the resistances and capacitance in series to get a single resistor, capacitor, and inductor? Can elements in series be reduced despite components in between them? If not, how else would we be able to reduce this circuit so we can get the ideal form to apply equations?


texts: Modifying a sliding foot dimmer KFD-527G for LED bulbs

texts:
I replaced the incandescent bulbs of a living room floor lamp with LEDs. This lamp was equipped with a sliding foot dimmer but since then, even when I put it on the minimum position, the LEDs do not go out completely.
I looked for the schematics of this dimmer to modify the minimum output power but without success. Could someone help me find these files or tell me if my plan can't work (hopefully not)?
I expect this dimmer to based on a PWM Thyristor but I could be wrong yet.
To be complete on this subject, I actually have two lamps which have two dimmers with different references: KFD-527G and KFD-325G3.
Note: obviously, I have looked for full replacement of the dimmers, I have found many solutions, but in the current situation of our poor planet, any repair or reuse is a small contribution to a larger effort.


texts:
I am basically having trouble understanding this circuit from a question asked on here.

Would be nice if someone could confirm that my understanding of it is right.

Here is what I have understood:

So without the cap, the voltage at the voltage divider output is 1 V .
With the cap , On switching on the power supply, I would expect 0 V at Vout, as the cap is initially discharged , and slowly as it charges, The voltage would keep increasing based on the R1C time constant. After it has charged, I would see a stable 1V at Vout .

And finally the graph will be like this :

is it the correct understanding for the circuit ?

Thanks


texts: How are higher dimensional sphere packings used in signal transmission?

texts: How are higher dimensional sphere packings (HDSPs) related to the error-correcting codes used by cell phones, space probes and the Internet for signal communication through noisy channels? HDSPs strike me as super abstract objects and I'm having a hard time even wrapping my head around their possible concrete applications.


texts: LED Array Controller Circuit PCB Design Questions and Feedback

texts:
Background
I'm designing a LED controller based on a Teensy 4.1, some AD9833 Function Generators and some TLC5948 LED Drivers. I'm aiming to make an instrument of sorts, specifically a POV display that transmits a series of musical notes via light to a solar panel + amp. I know the music won't exactly be visible due to the relatively high frequency, so I'm going to add that signal on top of an image signal. Thanks to the help of glen_geek on my question here, I decided to use  AD9833s to generate notes that I'll read in through ADC on the Teensy and use that data to adjust the LED PWM signals on the TLC5948s.
Problem
I'm wondering if a more experienced PCB designer can tell me what I'm doing wrong or if there's another way to achieve my goal.
This is my first attempt at a PCB, and I've hit a wall. I'm not really sure how I would go about routing the TLC5948s to the LEDs neatly. I added a picture of my first attempt, and to me it feels really clunky, messy and wrong. I could only get everything connected using 4 layers. I've tried looking up layouts for LED arrays/matrices for inspiration but I can't find anything that isn't designed for strobing the LEDs (i.e. common row/column connections). I'm not opposed to strobing but I haven't found any LED drivers that offer that as a feature and I'm worried that'll add audible noise to the music if it's not fast enough (ideally it should be above 20Khz so people can't hear it). Does anyone know if there's a cleaner/easier way to route this or an IC that can handle strobing at high frequency? This has been answered by @Justme.
Feedback
I'm also looking for feedback, both on the circuit design and the PCB layout. Two questions I have are:

Is there any way to make this smaller?
Is it ok that I cross some of the LED lines with clock signals? If not, is there a fix?

I tried my best to research the basics like decoupling capacitors and keeping analog/digital ground separate, etc, but if I've missed something else I'd love to know about it. Also, any ways to make the board more compact would be appreciated as well.
Thanks so much in advance!
Revised PCB Design #1
I made the following changes and reattempted the routing thanks to the suggestions from @Justme.

Use 3.3V for RF, AD9833s, and TLC5948s
Use 3.0V for Hall Effect Sensor (since output can be Vcc +0.3 and Teensy is only rated for 3.3V)
Change pin order on the TLC5948s to consecutive pins

Improved Design Pictures


texts: Adding anti-aliasing filter to op-amp before ADC, clock frequency or sampling frequency?

texts:
I am designing an anti-aliasing filter for an MCP3202 ADC.  I'm kind of confused by defining my corner frequency Fc, I'm working with a 60 Hz input signal with harmonics until around 3 kHz that comes from an air conditioner current signal, so I can say that the maximum frequency of my input signal is 3 kHz or 50 X 60 Hz.
The MCP3202 is a SAR ADC, with SPI output protocol, 0-5 Vdd, and its specification says "100kSps", that requires an input clock signal Fclk more or less of 1.8MHz, that is, to generate a sample it needs a clock signal of 18 X Fclk, supplied by a microcontroller.

As we know SAR ADC works with the "sample and hold" method to hold the samples and be converted.
I assumed that the internal R-C input of the ADC works with the ADC clock frequency Fclk, which generates my confusion because the output of the anti-aliasing filter is wired to the ADC (no bucket filter before the ADC,) so the filter "sees" the Fclk in the ADC's input.
Being more specific according to this information.
Does the cutoff frequency Fc have to be defined by the clock frequency Fclock if not, is Fc defined by the sampling frequency specified in the ADC datasheet (100 kSps?)


texts:
I'm starting to design things that run off mains voltage and I want to be sure that I have a proper connection from my chassis to earth ground.

I've been reading a bit about proper grounding and have learned the basics about stripping any paint off the chassis near the grounded point and connecting earth to the chassis as shown in this picture:

Image source

Finding the right hardware is easy enough, I plan on using all #10-32 machine screws and the associated nuts/washers.

I'm curious how other people on this site choose an "approved earth lug". I was thinking of using one of these.

I'm not exactly sure which agency's approval I am looking for. I'm also generally curious what other people have used in their designs. If some of you could share some part numbers for lugs you like to use, that would be helpful.

Additionally, I learned here that NEC requires the earth wire to be at least 14 AWG, while IEC requires 18AWG. I'm not exactly sure what situations call for meeting either of these specs.

So to summarize:

Can someone give a few examples of ground lugs they like to use in their designs? Extra points if it doesn't require an expensive crimp tool.
When is it important to use 14AWG rather than 18AWG for the earth wire?

[Edit: I should add a few notes that relate to agency approval. I live in the US and I'm designing devices for personal use, nothing to sell. None of my devices necessarily need to be approved by any agency, safety is my only real concern.]


texts: Fundamental similarity between resistor, capacitor, and inductors?

texts:
I notice that resistors, capacitors, and inductors share some fundamental similarities: for example, the way you compute their values in series and in parallel is extremely similar.
Likewise, it seems that if you said that resistors have a time constant of zero, they also follow the e^x timing law that inductors and capacitors share.
Is there some real fundamental similarity here (like an interface that all of these components satisfy) that causes this? Or is it just happenstance?


texts: Is it safe to connect Arduino/Netduino to car voltage source

texts:
On Netduino homepage it is stated that Netduino can be powered by input: 7.5 - 12.0 VDC or USB. The car output voltage is 12V but the car voltage source can produce voltage spikes so I am not sure whether it is safe to plug netduino directly into car voltage supply without any additional protection such as voltage limiter.

Does anyone know if it is safe to connect Netduino/Arduino directly to car voltage supply?

Thanks


texts: why is a GROUND electrode needed with a referential amplifier?

texts:
Physiological amplifiers seem to often (always?) have both ground (G) and reference (R) electrodes along with one or more active (A) electrodes.
Typical voltage at an active site is determined AFAIK as [(A-G) - (R-G)] = A-R.
I haven't managed to find out why the ground electrode is needed at all and why the amplifier cannot simply do the A-R calculation directly without the need for the ground electrode?
Is it because when there are multiple active electrodes that A1-R and A2-R couldn't be done without them interfering with each other?


texts: Are lamps connected in series on airports?

texts:
Long ago I learned about connecting things (e.g., lamps) in series and in parallel. A famous example of lamps connecting in series was at an airport, especially to indicate the landing strip. The purpose was to guarantee that all lamps would work together. If one lamp would be bad, all lamps would be off and no distorted signal would be visible.

Now I know that it is bad to connect incandescant lamps in series. Such lamps should be connected in parallel, or one lamp that would be just a little bit more worn out would get destroyed even faster because the series connection would result in a constant current supply, disastrous for lamps with a positive temperature coefficient, leading to thermal runaway.

Of course this is a historic question. Today, with LED lamps, the situation is exactly opposite. Leds must be connected in series and fed with a constant current. In parallel, one led with a v/i curve that is just slightly lower would be destroyed by the other leds.

With that knowledge, it is hard to believe that airport lamps (not led) were really connected in series. I googled on this and could not get answers. Does any one on this forum know about the application of lamps connected in series?

The only answer I do not appreciate is lamps for the christmas tree, because these were virtually always defective because of the reason stated above.