texts: Harmonic distortion and Nyquist rate (Spurs above the Nyquist rate of a DAC)

texts:
I have been reading an article during the past few days for a project I am doing and I've come across a point that bugs me out.
It is about improving the spurious free dynamic range (SFDR) of DACs.

https://lirias.kuleuven.be/bitstream/123456789/171625/1/Gielen_3_Full_Paper.pdf?origin=publication_detail

On page 7, the authors say that the greatest spur is two times the signal frequency, and base their estimation of the SFDR on this hypotheses.
However for a high enough signal frequency, the harmonic distortion is greater than the Nyquist frequency.

My question is : What is the point of calculating the power of the spurious frequencies over the Nyquist frequency? The output frequencies greater than the Nyquist frequency should be filtered out right?

I am quite new to electrical engineering so I might be missing fundamental concepts here but after quite a long search I can't seem to figure this out.


texts: What defines whether a CPU should be in LGA of PGA package?

texts:
All modern Intel CPUs I know are in LGA package. At the same time, AMD CPUs mostly are in PGA packages, with only server ones packaged in LGA.

What are the reasons for Intel to use and AMD to not use LGA for majority of their CPUs?


texts: How do I tune this PID for my coffee machine?

texts:
I have tried to reach out to the developer of this software with no success. There seems to be an error in the code, and when you follow the steps, the last step does nothing.
Steps for PID Tuning (Ziegler-Nichols Open-Loop):

Set to Manual Mode and 100% Duty Cycle
Wait for Temperature to increase by at least 10%
Turn Temp Controller off and Stop data capture
Highlight Sloped Line after Dead Time on Plot

(I would have assumed in the bottom right corner it would suggest new values but in the Java code you get an error (when you highlight you get 0,0 instead of what's actually on the graph.)
Anyway. I have researched how to adjust/tune a PID, but whenever I try to cross-reference this one, the letters don't match up. Usually kp ki etc. but I have PID Kc parameter, PID Ti parameter, PID Td parameter.
So can anyone suggest how I can tune this manually?
And also explain to me what these inputs mean? Actually ELI5
I know the setpoint is the target temp, but I don't quite understand duty cycle and cycle time or actually any of the rest.
This is the web view of my espresso PID controller:

Thanks a lot for your help.  Once again, I'm not really looking to fix the broken issue with the Java code, just want some sort of translation so I can manually tune this PID.


texts: Is It Possible to Reroute I2C Path from One Device to Another if End Device is Same?

texts: I have a master and slave device that has two MUXs inbetween. Let's call these MUXs MUX1 and MUX2, and layout goes MASTER --> MUX1--> MUX2 --> SLAVE DEVICE. My design also has a separate MUX called MUX3 that's also connected to MUX1 and SLAVE device that's currently not in use. Would it be possible in SW to reroute my current I2C to go from MASTER --> MUX1 --> MUX3 --> SLAVE DEVICE?


texts: Would connecting multiple light socket splitters together decrease lumens

texts:
Sorry if this is a noob question. I'm trying to build a very bright light by combining multiple light bulbs together with socket splitters. My thinking is simply to take three 7 in 1 light socket splitters and combine them to give 5 + 7 + 7 = 19 total sockets. If  I put a 1000 lumen led light bulb in each of these sockets, will I in practice have a 19000 lumen light or is there some reason in practice why I might end up with much less than that? (i.e. is my calculation naive).
Edit: here's what I mean by a light socket splitter:

Idea is that I would connect another splitter in two of those slots instead of a bulb (assuming this works?). I may replace the ceiling bulb or possibly use a lamp stand in order to move it closer and increase the actual lux that's hitting my face.
The bulbs would be probably be 17W LEDs (maybe higher if I can find them). I'm in the UK, where the voltage limit is 230V.


texts: Improving ease-of-soldering in home-made boards

texts:
I am making a PCB with a subtractive PCB mill, and I am having difficulty soldering some components to the finished copper. The solder isn't flowing onto the traces easily, and by the time it does flow, the pad lifts.

I'm not sure if the boards need to be cleaned more, or if they need to be covered with a tinning solution (or both). What can I do to make the board easier to solder?

When should I clean my boards - just before or after milling?


texts:
I am using a CAN Bus shield for a raspberry pi which uses MCP2515. I want to wakeup the connected CAN device, send a message, and put it back to sleep. I am aware there is a sleep mode on CAN transceivers but am not sure if it works the way I intend to implement it.

I am new to CAN bus and electronics so I was looking for some help with this.

Here is the data sheet for the MCP2515: https://seeeddoc.github.io/Open_parts_library/res/310070025.pdf

and the PiCAN2 (RasPi CAN Bus Shield): http://skpang.co.uk/catalog/images/raspberrypi/pi_2/PICAN2DSB.pdf

Thanks!


texts: What determines whether a household device needs a grounded plug?

texts:
Why do some UL-listed household electronic devices have grounded plugs, even if they have no exposed metal on their case?

E.g., I have a plastic-encased laptop AC/DC power supply that requires a grounded plug, but my TV (which also must convert household AC to DC) does not have a grounded plug.

I thought the only purpose of a grounded plug was to catch a short that might energize some conductive part with which a user might come in contact.  What are the other purposes?  Or when are they indicated or required by regulators?


texts: Op-Amps with unequal split supplies (e.g. V+ = 25V, V- = -11V)

texts:
Most electronic designers will be familair with designing op-amp circuits with a single supply rail (e.g. Vs+ = 5V, Vs- = 0V) or matched split supplies (e.g. Vs = +18V, Vs- = -18V).

I have a design where I need to handle both +24V inputs and -10V inputs.   Of course, there are some off-the-shelf parts that can handle +/-40V supplies, but my choice is rather limited.

On the other hand, op-amps with 36V supply voltages are plentiful, and given my voltage span is +34V, a carefully chosen rail-to-rail input/output (RRIO) op-amp should be up to the task, if I can make the supplies +25V, -11V.

This would make the design rather unusual (to say the least).  What do I need to pay particular attention to when designing for this unusual arrangement of supply rails?  Or, am I simply better off going for the high-supply op-amp?

EDIT: Do I, for example, need to take into account the following:

A higher than normal offset voltage/bias current?
Problems with matching between bias current and/or offset voltage between channels?
Changes to distortion?
Any other likely specification changes?


texts: Pad and soldermask dimensions in PCB design

texts: I found that usually on BGA package and on a lot of QFN datasheets are provided IC and PAD-IC dimensions and not advised PCB-PAD dimensions and soldermask dimensions. Can someone tell me a good rule between IC-PAD dimensions to PCB-PAD dimensions and Soldermask dimensions? For BGA and QFN.


texts: Using a CP2102 USB-Breakout to Program an ESP8266 on an NodeMCU v1

texts:
I have a NodeMCU board with a broken UART module. So I tried to program the esp8266 via an external CP2102 breakout board. I have powered the NodeMCU directly with 3.3V on the 3.3V pin and connected TX/RX/GND of the CP2102 breakout board.

I am able to receive the "ets Jan  8 2013,rst cause:2, boot mode:(3,7)" via the serial monitor of the arduino ide. But I just get an error when I try to program the esp826 with the arduino ide:

  warning: espcomm_sync failed error: espcomm_open failed error:
  espcomm_upload_mem failed error: espcomm_upload_mem failed

What I am doing wrong? I am pressing Flash, tap reset and release the flash button on the nodemcu board.


texts:
I am working with a flexiforce pressure sensor 25 lb.

I have to run 6 of them in parallel and I'm using an Arduino Uno. I'm not an electrical engineer (read: I'm a computer science major) and this is a school project. I am using a voltage divider for a single flexiforce to test the range and I don't know what the best fixed resistor value to use in order to get a larger range.

I am currently using a 200 Ohm resistor and am getting range from 0 to 30 (full range is to 1233)

Here is there recommended circuit:

Using the Arduino, I can't make the amplifier thing or have a negative voltage input. Can someone please explain a way to get 6 of these sensors in an array with the highest sensitivity? Can I use a 9 V battery as an amplifier?


texts: bernina motor capacitor exploded. How to repair motor

texts:
My girlfriends Bernina sewing machine exploded and catched fire. It made a lot of smoke, probably wasnt very healthy. Now what the bernina store said was to get a replacement motor but that also means to get another foot pedal and the 60's sewing machine comes with a very good pedal and (silent) motor.

Now i wonder where I can find a specific capacitator like this.And if we change the capacitator is there a high probability the machine will just work?

Maybe somebody also knows why it exploded? As it has served good for a really long time.. Might it have something to do that the capacitator was calculated for 220v instead of 230v

I can post only two links, the other information (or rubbish) given on the machine is:

capacitator:
leclanche fo= 2/3,5MHz 6O0O    O65   285160

motor:
Scintilla SA
type HG/NMB 220v 50Hz
75/32Watt 5700/min
45/15Watt 3500/min
(made in switzerland)

any help is welcome!

greets
d


texts:
I'm new to these forums and have very little background in electrical engineering.

I'm trying to figure out the number of "don't care conditions" based on an input of two numbers, each 0-9, for designing a digital system to implement the multiplication table. The output would be the product of the two numbers.

I don't have a very good understanding of what "don't care conditions" are. My understanding is that they are based on inputs that are "unlikely".

Are the number of don't care conditions 9(since we "don't care" about the product of any number and zero)?


texts: How to get the most power efficiency of solar panels?

texts: I am doing a project about solar panels and I will like to know what is the best way to connect 2 small solar panels and get a high power efficiency?


texts:
I'm trying to model a diode as two capacitances, a conductance, and a series resistance, as shown here:

In order to generate an expression for the capacitance I'm equating 1/w3db to the time constant of the system. In the past whenever I have needed to determine a time constant its been possible to decompose the circuit into equivalent resistances and capacitances. With this circuit however, it seems like that approach wouldn't work, due to one of the resistances being mixed in with the capacitances.
Am I overcomplicating things? Can I just take the resistances in series and the capacitances in parallel?


texts: How do I calculate the impedance of elements in a circuit given only equivalent impedance and angular frequency?

texts: See photo included below. I've tried working this problem for an hour using phasors, voltage/current dividers, and Ohm's law, but I can't figure it out. It's given that equivalent impedance Z_eq = 2-j2 kOhms and that frequency is 4000 rad/s, but I don't see how to find the individual impedance a of the elements in the diagram. Any ideas?


texts: Hook up a load cell with High Level Amplied Output (only input+ input- output+) to load cell amplifer

texts:
I have been successfully hooking up load cells (e.g., TAS606, red = E+, green = O+, black = E-, and white = O-) and load sensors (with help from a load cell contaminator ) to load cell amplifer (e.g., HX711). essentially the input should have at least four pins as shown below:

Now i have received a TE Connectivity Voltage Compression Load Cell Maximum of 22.67 kg, 5V dc where there are only three output pins as shown in the figure below:

How should i hook up this load cell with a load cell amplifer like HX711?
Thanks.


texts: 3.7V Lithium ion battery supply and Arduino Uno

texts:
So many people have asked questions related to mine already, but mine is not quite out there. So my question is I have a 3.7V Lithium Ion battery and I need to power Arduino Uno, which requires a minimum of 7V. I found some voltage doubling circuits, either they are using an external component(like mosfets, etc) or the circuit is for AC.

Is there any simple voltage doubling or any another easier way using resistors and capacitors?


texts: Getting the right converter for this 110/120v device, where the power is 220/240v

texts:
I have an appliance designed for 110/120v. It says it runs peak at 1200 watts, but I can't find yet any mention of Amps. I'll be using it in Europe at 220/240v, if it is possible.

I understand I can get a converter, but from what I've read it isn't just as simple as getting a 220/240 => 110/120 volt transformer. Or is it?

How do you calculate this?


texts: Altium Designer - Prevent snapping when using the "Measure Distance" tool

texts:
I want to measure the distance from point a to point b in the PCB editor. However point b is surrounded by pads and primitives, thus when I try to move my cursor to point b, the cursor keeps snapping to the pads and primitives. Under normal circumstances I love this snapping feature, but sometimes I require a specific measurement that the snapping feature prevents me from doing.

Is there a method to quickly switch between snapping and non-snapping when using the "Measurement Distance"  tool?


texts: Use CP2102 as self-powered or bus-powered

texts:
I'm drawing a LiPo 3.7V charger circuit. This circuit contains a power path to continue delivering power to the circuit, or by battery or usb. In the final of the circuit I've an LDO to 3v3.

Now, I want to use CP2102 as an RS232 converter and my question is: Should I supply CP2102 with power from the BUS pin?

Or should I feed it with the 3v3 that come from the LDO?

The second options seems to be better to me, becouse:

I don't need the 3v3 from voltage regulator (REG0)
Using Bus as supply it could affect the behaviour of my power path?!

I've a few more questions about it.

Whenever I disconnect VBus the CP2102 automatically enters on standby mode?
Should I use any pull-up resistor on D+ and D-? Datasheet doesn't make any reference to that.

Best Regards


texts: calculating FSM's maximum clock frequency

texts:
Let's assume we have the Truth Table for our Finite state machine.

How can we determine the maximum clock frequency for the system, under the assumptions that the wire delay is 0.3 ns , flip-flop setup time is 0.2 ns, and gate delays are 0.4 ns for 2-input gates and 0.5 ns for gates with more than 2 inputs.

Firstly I should find boolean function for each output, outputs to real world and outputs for next states to controller I guess.
Then what?

Thanks in advance, btw this is my first question in electronics :)


texts: Is this the right way to connect a Brushless Motor Driver Output Signal to a CNC BreakoutBoard?

texts:
I will purchase a Spindle Brushless Motor Driver to drive my Lathe Spindle, and I need to know if I´ll be able to connect an output signal from the Driver to my CNC BreakoutBoard (BOB), which is a GECKO G-540 G540 Manual, and they don´t share common grounds.

As this is a Chinese Driver, It lacks detailed documentation, so there´s no datasheet yet, only an user manual.

The Chinese driver is powered from 220VAC and internally it has 5V logic to it´s motor controls. (The bruhless motor is powered by 310VDC internally)

But I need to read this alarm signal.

What I know from the lack-of-info-manual is that the alarm signal outputs 5VDC when in normal use, and 0V when in Fault State. I´ll attach 3 pages of the manual, as jpgs, that have details about  how it works:

So, as I don´t have all the info needed yet, I though of this opto-isolated circuit (Based in a help I had with user @transistor in another question) to interpret the signal over my CNC controller, without the risk to fry it.

I just don´t know if I could risk damaging the driver by connecting the Alarm signal to ground with a 330R resistor, and if it would work or not.

EDIT: The Chinese dealer sent me this partial schematics of the part where the ALM (alarm) signal is created and sent:

So although it has some kind of internal isolation (there´s an optocoupler inside) would it be safer for me to use another optocoupler between ALM (5V or 0V) and GND1, as I drew on my diagram, to completely separate both devices (driver and BOB)?


texts:
My objective is to build a Circuit which will draw current from Solar Panel, recharge a battery as well as run the load even if voltage from solar panel goes too low.

I have made the following circuit, where V1 is a Solar Panel 3-10 V output, BAT1
is a Rechargeable Li-ion battery, LOAD is a submersible pump which draws about 100 mA.

simulate this circuit – Schematic created using CircuitLab

Will the circuit perform my objective?


texts:
The typical name I see given is MPC, MPC2, or MPC-2, and the cables are readily available, but I can't seem to source the female PCB-side connector. Obviously, a 1x4 pin header would work just fine, but I'd like to use the locking connector if possible.
This is what the cable looks like:

(source: connectworld.net)


texts: How long can a 555 be run on a 9V battery?

texts: Is there a way to figure how long can a 555 run on battery, when reset is grounded, to have no output?


texts:
For my EE lab, our professor wants us to show switch bounce, and then eliminate it using hardware, and software debouncing.

However, I seem to be stuck on finding the switch bounce in the first place. Attached is a snapshot of my scope when the pushbutton switch is triggered. To my untrained eye I can't be sure if what I am seeing is actually even switch bounce, or simply transient LC-voltages. How do I tell the difference, and/or is it just possible that the pushbutton I used has almost no bounce?

Edit Attached circuit

simulate this circuit – Schematic created using CircuitLab


texts: Find the Thevenin's equivalent of a circuit between nodes A and B

texts:
My class had come to discuss the Thevenin's theorem and we stumbled upon this particular problem which quite confuses me in a way that what I found is different than what my lecturer taught us. So, the problem goes like this

simulate this circuit – Schematic created using CircuitLab

Apparently, we can make use of the leftmost loop there and get

$$2k\cdot i(t) + 3v(t) = 5 V$$

which is equal to

$$i(t) = \frac{5 - 3v(t)}{2000} ...(1)$$

I can understand that. I also understand that looking from nodes A-B's point of view, we have

$$v(t) = V_{Th} ...(2)$$

and therefore, making use of the rightmost loop before nodes A-B, we have

$$V_{Th} = 20i(t) \cdot 25 ...(3)$$

Inserting (1) to (3) then gives us

$$V_{Th} = v(t) = \frac{5}{7} \approx 0.714 A$$

which I understand too. However, my lecturer somehow put a negative sign on (3) and thus the original equation would turn out like this

$$V_{Th} = -20i(t) \cdot 25 ...(4)$$

These two equations would, of course, lead to totally different answers. My lecturer's method would lead to \$E_{Th} = -5 V$. The thing is, I couldn't figure out why it is necessary to put a negative sign there. So, in short, my question is, why is there a negative sign? Any answers would be much appreciated.

To add some context, the complete solution (according to my lecturer) to the problem goes like this. We short A and B and assume that there is a short-circuited current that goes through both nodes A and B. Let's call it \$i_{sc}(t)\$. And thus
$$i_{sc}(t) = -20 \cdot i(t)...(5)$$
(notice that there is still the negative sign) and since we shorted nodes A and B, there will be no voltage between the two, and so we can write it down as \$V_{25 \Omega} = v(t) = 0\$.

As \$v(t)\$ is equal to 0, we can infer that the dependent voltage source on the leftmost loop becomes irrelevant to the equation of that loop, and so we get
$$i(t)=\frac{5}{2000}=2.5 mA...(6)$$
Inserting this to (5) will give us
$$i_{sc}(t)=-20\cdot 2.5 = -50 mA...(6)$$
This will then lead us to the value of the last unknown
$$R_{Th} = \frac{E_{Th}}{i_{sc}(t)}=\frac{-5V}{-50mA}$$


texts: LEDs and weird results from various Arduino pinModes

texts:
I'm currently repurposing an old Arduino project - it consisted of several super bright LEDs wired according to the following schematic:

The same configuration is repeated with pins 3, 5, 6 (and not shown to keep things simple).

I was controlling the lights via serial, and managed to PWM them without any issue.

For my current project, I want to work with code uploaded through the Arduino IDE. I kept getting weird results as I was trying to PWM them, and tried to simplify my code until I got to the following three test cases:

void setup() {
    pinMode(6, OUTPUT);
}

void loop() {
    digitalWrite(6, HIGH);
    delay(500);
    digitalWrite(6, LOW);
    delay(500);
}

Expected result: the lights connected to pin 6 blink.

Actual result: the lights flicker once, and not do anything at all.

void setup() {
    /* pinMode(6, OUTPUT); */
}

void loop() {
    digitalWrite(6, HIGH);
    delay(500);
    digitalWrite(6, LOW);
    delay(500);
}

Expected result: nothing should happen.

Actual result: nothing happens.

void setup() {
    pinMode(3, OUTPUT);
}

void loop() {
    digitalWrite(6, HIGH);
    delay(500);
    digitalWrite(6, LOW);
    delay(500);
}

Expected result: nothing should happen.

Actual result: the lights connected to pin 6 blink. Wait, what?

My wiring solution may not be ideal, but it worked when I was sending instructions by serial. Any ideas as to what could cause this behaviour?


texts: I would like to know how a 78xx series linear regulator can be used in a switching application. I have found a circuit that shows such a use, but I have trouble understanding how the circuit oscillates. Additionally, how would one choose the Zener diode?


texts: How to control 400 RGB LEDs individually?

texts:
I've got a little home project that I want to start. I don't have really have any experience in this field. So be gentle.
I need control up to 400 RGB LEDs individually.
They only need to function in 3 states - off, red, blue.
I would position them in a grid layout and each state would represent a different position.
Any advise anyone can give.
Would be great.
Thanks.


texts: What is typical interface for WLAN chipset on a modern smartphone?

texts: Taking into account nowadays Android smartphones support WiFi 802.11ac, what interface is being used for interconnecting of WLAN chipset with Application CPU? Is it SPI or some other? Is it OK to expect that SPI interface will handle such speeds as 400 Mbps and more?


texts:
I’m hoping someone here can help me with a long overdue project. I’m trying to figure out how to wire multiple CCFLS to one power source + inverter... so far not much success on my own.

I’m currently able to run up to 3 CCFL's in a series, at varying lengths either 3x 6”/152mm or 3x 12”305mm, off of an AC/DC converter  + inverter
(Input: 120V/60Hz/12VA Output: 6V/800ma)

Can anyone shed light on what range of AC/DC converter + inverter I would need to run 6-12 CCFLS in a series?  Here’s an example of this series in action, really want to figure out how to do it myself. Any help appreciated!

Some specs I found on CCFLS; keep in mind the one's I have came as is from a liquidation center, they are just loose CCFL's no manufacturers info etc.

Inverter Requires 12 VDC (can go between 14VDC-6VDC safely) and Generates as much as 1000VAC to power lamp tube. The lamp requires 800-1000VAC (?)
Power consumption between 350-400ma at 12VDC (4.2-4.8watts). Inverter needs 12VDC, wall plugs give 120VAC, AC/DC converter is fine as long as you’re getting between 350-400ma to the inverter.

Specs from one CCFL producer:
For a 6”/152mm Cathode:
For a 12”/305mm Cathode according to this provider:
Starting Circuit Voltage 1000VS (Vms)
Operating Lamp Voltage:  400 (Vms)
Operating Lamp Current: IL (mAims) 5
For a 12”/305mm Cathode according to this provider:
Starting Circuit Voltage 1750VS (Vms)
Operating Lamp Voltage:  780 (Vms)
Operating Lamp Current: IL (mAims) 5


texts: What do I need in order to make my arduino to transmit / recieve signals exactly at 433.68 MHZ?

texts:
Before I start, please note I am not even near to be an expert in electronics - I just try to do my best with what I have - I apologize in advance if my language is not technical enough.

I have a power generator that can be started using an included remote controller transmitting at 433.68 MHZ according to the FCC ID (https://fccid.io/YA3V750)

I already contacted the manufacturer and they literally told me they don't make any kind of hardware to automate the power generator (of course, they offered me  a new one with this functionality included).

AFAIK, the transmitters / receivers available for Arduino are either 315/433 MHZ, but I am somewhat concerned that, if the power gen receiver is set to 433.68 MHZ, it might not receive the 433 mhz signal.

So far I already devised a plan and schema for closing switches using relays, activating servos for gas and main power switch, Hall sensors for detecting when the power is out, or the voltage is low... so now I am facing this little issue: When Arduino detects main power is gone, it should send the start signal to the power generator using a rf transmitter; once power is back, send the stop signal - but at 433.68 MHZ.

Any opinions / suggestions?

Thanks in advance.


texts: What is the name for an IC that accepts an analog voltage and outputs a proportional PWM signal?

texts: I want to isolate an analog signal. One way of doing this is to convert the analog signal to PWM, isolate the pulses with an optoisolator, and filter the PWM on the other side. Obviously I could do this with a microcontroller, but I feel like "convert analog to PWM" is a generic enough function that there should be an IC to do exactly that. Like most things, it's difficult to google something if you don't already know the name. What am I looking for?


texts: Why does this 5 V power supply work and the other one doesn't?

texts:
This is my first post here, I hope I'm in the correct area.

This is my problem, I bought this circuit to receive caller ID over protocol DTMF.

I have a few 5V power supplies here, (0.45A ,1A and 4.6A), both (0.45 and 1A) works with my circuit, but the 4.6A doesn't.

Also I tried to use my USB port. It works until I connect my USB printer to the computer, then it stops working. (With "works" I mean, the circuit is able to detect the caller ID, because all of them, turn the circuit on.)

And if I use the power supply of 0.45 or 1A, and connect the ground together with the one with 4.6A or the ground with USB port when the printer is connected, it stops decoding the caller id.

With an USB power bank, the circuit works too, does anyone know what is going on with my power supply?


texts:
This part apparently supports ESD protection of eSATA. But SATA interfaces are AC coupled. This means their common mode voltages could well be centered around 0V, with negative voltage swing. On the diagram for this ESD part, I can see that there will be a problem with it clipping any negative voltage swing below -0.7V.

Am I understanding this right? How can this part possibly support eSATA? The other interfaces such as USB3.0 and DisplayPort are also AC-coupled. Am I missing something?


texts: Decoupling cap on backside: Create separate via?

texts:
There are already many questions about proper placement of decoupling caps in different situations (multiple layers, different sides etc).

As a general rule of thumb (e.g. How to place decoupling capacitor in four-layer PCB?), it is frequently recommended to directly connect the decoupling caps between the IC pins and from there a via to power/ground plane. The reason is to ensure that the currents flow through the cap.

Based on this Decoupling cap: Closer to chip but with via or farther without via? and this How important is it to put decoupling caps on the same side of the PCB? question I have decided to to put my caps at the opposite side. Furthermore, I will have an 8 layer board with multiple ground planes/power planes.

In order to connect my decoupling caps I have a forest of vias from the VDD pin to the other side of the board. On the other side, I connect the caps between the ground paddle and the vias.

However, in order to follow the rule of thumb above, I should not connect the vias to the ground plane. Instead, use separate vias to connect the cap to the supply plane.

This seems quite wasteful and odd to me. To make the long question short:

When placing decoupling cap at the other side of the board, is it ok to connect the power/ground planes with the same vias that connect the cap and the chip or should they be separately connected?

In order to give a precice example, this shows front and back layout:

As can be seen, the 6 vias labeled Vdd1V2 also connect to the power plane Vdd1V2 directly. I do not have separate vias to connect the (then local) Vdd1v2 network on the back to the power plane.


texts:
This is an example about input offset of a comparator in Analog Integrated Circuit Design by Tony Chan Carusone (page 414).

Could anyone explain why the plot in Fig 10.1 is a normal distribution?


texts:
I am trying to measure the presence 60 Hz AC signals using various shapes of wire antennas.
I will be sending the voltage present on these antennas into a high impedance op amp stage. But before I do this, I would like to know if I can get away with measuring the AC voltage with a O-scope probe which does not use the ground clip. I have taken several different measurements in locations where there was a strong E field and a weak E field.

Additional information added 5/27/15:

The goal is to determine whether 60 Hz is present as well as to determine whether the voltage measured at a given position has increased if the antenna is move closer to the source. I will be sending this voltage to active components downstream. I was just want to know if connecting my O-scope probe to various length antennas without using the ground clip invalidates the reading.

Thanks

Tom


texts:
As shown in title: what's the difference between linear modulation and non-linear modulation scheme?

I can not find the formal definition of this.
And there is a different determination for the FSK modulation (linear and non-linear).

FSK is non-linear

FSK is linear and can be classified using likely-hood ratio function

While the GMSK is non-linear according to the searched results, however I don't know why.

Thanks for any help.


texts: Synchronous demodulation with single supply op-amps

texts:
I am looking at the following article from Analog Devices: Use Synchronous Detection to Make Precision, Low Level Measurements, and I'm wondering if there is a way to build the following demodulator circuit (Figure 4 at the linked site) with a single supply op-amp:

Any ideas out there?

EDIT

This circuit appears to work just fine with a single supply op-amp. I think I had the switch direction backwards the first time I tried simulating it. The switch should be set up such that the gain is +1 when the sync signal is high, and -1 when the sync signal is low. Below are images of a spice simulation showing this working with the LT1498 on a single +3.3 V supply.


texts:
I recently bought a GTU 10 from Garmin.

I want to extend it's battery life by replacing and soldering on a new battery and enclosing the battery and the GTU 10 in a 1601 Otterbox.

I would like to be able to charge the new battery through the USB connector on the circuit board, so is it possible to do? What should be the specs on the new battery?

After removing the shell, you are left with a 3.7v, 740 mAh, 2.7Wh
battery and the circuit board.

Battery.

GPS Side


texts:
I am trying to set up a circuit to use the LMR16030 buck regulator to step down 60V to 9V. I bought the Powergood version and I'm not sure how to connect the power good pin.
As you can see in the datasheet on page 3:
http://www.ti.com/lit/ds/symlink/lmr16030.pdf

"PGOOD pin for Power Good version, open drain output for power-good flag, use a 10 kΩ to
100 kΩ pull-up resistor to logic rail or other DC voltage no higher than 7 V."

I'm not sure how to apply this as I do not have a DC voltage at 7V in my circuit.

I based my circuit on the application section of the datasheet page 19 and encountered a few problems with the Powergood pin open. I first forgot to connect the GND and obtained the desired voltage, but oscillating, as my arduino was turning on and off rapidly. When I then noticed my error, I connected the GND pin properly and it instantly shorted with a big spark at the GND pin. Could this be due to the fact that I left the PGOOD pin opened?

Thank you for your help!


texts: MOSFET driver or something with similar function for highside back-to-back MOSFET switch

texts:
I want to supply a microcontroller with 4x AA alkaline batteries or via USB, with the USB source being dominant. Meaning when USB is on, the batteries should be disconnected.
For the USB path, I intend to use a Schottky diode.
For the battery path, I initially thought about using a "ORing" IC or one of those "powerpath" controllers. The problem with most of the ones I've seen so far is, that they only have one integrated FET, so there could be a reverse current flowing into the battery when the batteries drop below the USB voltage and the forward voltage of the FET body diode.
I want to use two back to back FETs with common source, but I'm not sure what driver would be suitable.
One way I thought of would be to use a MOSFET driver like MAX1614 and let it drive two FETs. But the MAX1614 only goes down to 5V Vin which would be too high. Something like 4V would be better to get the most out of the batteries.
Vin is between 4V and at least >7V, if possible >12V.
But most of the drivers I find are for lowside configurations and some barely go above 5.5V.
Then there would be ones like the MAX5048 or the MAX15070 that go down to 4V.
Or I could use an ORing controller with external FETs, something like a LTC4412 or LTC4359 (looks like the 4359 is hard to get in Germany) and then use the enable pin to shut them down when the USB voltage is present.
I tried to design a discrete circuit with MOSFETs and transistors but that didn't work very well, I lack the experience.
Does someone have tips or ideas on a good approach, or alternative MOSFET driver ICs?
Edit:
This was my general idea for a discrete circuit, but I didn't choose proper parts yet. When I simulate this in LTSpice, I get a huge spike for Vout when it switches from USB to Batt. (from ~4.7V down to 0V and back up to 4V)
I think an output capacitor is needed to prevent that spike.

simulate this circuit – Schematic created using CircuitLab


texts: Is it easier to implement sigma delta modulator in FPGA by filter or state space model?

texts:
Sigma delta modulation is extensively used in quantization to reduce quantization noise.

In the literature one can see different architecture for example python-deltasigma to implement a modulator. One can learn the output of the modulator by implementing the filters or one can convert the problem into a state space model and design the modulator based on A,B,C,D parameters of the state space model.

The question: If we want to implement the modulator in FPGA which appraoch we should try? FPGA is always resource constraint so state-space approach or filter approach?


texts: eliminating those unwanted op amp[TIA] outputs

texts:
my problem statement:

i wanted to digitalize  10ns pulses from a photodiode which are in the range of current 100uA to 1mA (these were earlier much larger in range, dealt here, soon I have understood the gravity of the problem statement and changed them with suggestions by other members)

my circuit approach:

this may not achieve the full performance but still can satisfy requirements to a level

simulate this circuit – Schematic created using CircuitLab

Results:

Input:

TIA requires a current input pulse, so I have created a current source using a voltage generating pulse generator with series 1K resistor, so to generate a current input of 100uA, I have given an input of 100mV from generator

sorry I don't have  a generator with sharp rise/fall times, I was feeding 12ns pulse with rise and fall time of 6ns

stage 1 opamp output (LTC6269) and corresponding LVDS output are shown, which have satisfied me initially, but below response is one i see frequently, some kind of repeating reflections or noise are seen close to the pulse

view 1 :

view 2 :

view 3 :

I have initially thought these may be noise, but as they are repeating I have not understood what exactly are they.

soon I have understood that these repetitive noises are present in the function generator output at low levels, but I don't know what caused this, did my 1K series resistor to TIA has caused these?

so I suspected my setup, now I tried to place the actual diode in place of the current source, which have shown no results at all, i have seen noise even with out any light source illuminated, which is undesired,so i removed the diode, when i power the circuit even with out input i get a output as below with a repetetion

is it because of improper grounding ?? or any low frequnecy noise ??

please help me in finding the root cause of the problem

EDIT/UPDATE 1 :

the power supply is generated on board, using below setup, the 12V comes from a regulated power supply, LTC6269 would require +/- 2.5 dual supply , so the below is modified by tweaking resistors, LTC6754 requires only +5V and OPA699 would require +/- 5V dual supply.

coming to probe i am using a 500Mhz 10Mohm probe with capacitance 11pF and in scope i have set ac coupling with 1Mohm impedance

i am clue less to find the source of the this periodic noise, primarily i suspected function generator but now i feel its there even no source is present, can an opmap generate such kind of noise ???

EDIT /UPDATE 2 :

output of opamp and ground, both auto scaled show similar noise pattern(green is signal ground), may be due to non isolation of Analog signal ground and power supply ground ?

EDIT UPDATE3 : Results after addition of pi filters at dcdc outputs

with some suggestions of pi filters i have tried to create a CLC filter using components at my desk

L = 10uH and C being 4.7uF, 47uF, 0.1uF and 0.01uF(all 0603 SMD)

i did not get a 1nF but i was able to see noise suppressed to an extent, this set up is bare soldered and checked whether filter output is proper or not, i did not solder this on actual board, instead i took +/-5V from board and checked the filter output

With out CLC

After CLC


texts: STM32: SPI hardware to implement custom serial interface

texts:
I want to implement SDLC communication on an STM32 (assume I can pick any one up to M7) using the existing HW in it.

SDLC is a full duplex synchronous serial interface. In my case, it uses differential signaling (RS-485), so I am using some MAX488 to convert the differential signals to single ended signals.

So I have Tx Clock and Data, Rx Clock and Data.

I was thinking about using one SPI as master for transmitting the data and one SPI as slave for receiving the data.

A few questions:

Is this possible? Is there any better way to achieve this with only an STM32?
How can I generate 153.6 and 614.4 kHz clocks for SPI Tx?
Can the SPI slave receive any clock? Like 614.4 kHz?


texts: Can I charge a 12v sealed lead acid with an old wall-wart (not made for charging)?

texts:
Will it hurt the battery?  If I left it overnight would I run the risk of "exploding" the battery?

I have a 7Ah SLA battery that I need to charge, but I don't have a charger and I don't want rake out $50 for a charger.  Even if I did I need to charge it by the weekend, so I probably couldn't even get it in time.

If I use a 1Amp wall wart it should take 7 hours to charge the battery.  Would it be bad for me to plug the battery in for 7 hours and then unplug it when the voltage is about 13.5-14volts or so?


texts: Working out the Transfer Function of a PLL Loop given by the Analog Devices ADISim Tool

texts:
This is a followup question to this question, I asked previously.  My synthesizer PLL still isn't locking and it must be the introduction of the mixer and filter into the loop that's causing the issue (since the PLL works just fine without these).  I'm using the LPF determined by the Analog Devices ADISimPLL design tool.  This tool is oblivious to the extra stages I've added to the loop, so it's no surprise that the loop is unstable really.
Anyway, the obvious problem with having ADISim calculate the LPF for you is that it doesn't supply an accompanying transfer function (that I'm aware of), so you can't adapt the filter to handle different loop architectures like I'm trying to do.  So, I've had to go back to fundamentals and try to figure out the TF for myself.  I'm starting with the "bare-bones" PLL loop given by ADISim and plotting a Bode chart to see if it matches that given in the tool.  After that, I plan to introduce my additional stages (mixer + LPF) into the loop to try calculate the correct LPF component values.  Not sure if that will work out, but that's the plan and I'm learning loads as I go.
So, that's the background and the following is what I've achieved so far.  My question is, how have I done?
System spec:

Circuit with LPF suggested by ADISim:

Transfer function calculation overview:

If I expand H(s) by including F(s) I get the following:

I've substituted in the values given in the ADISim circuit to arrive at a final transfer function.  This is essentially a third-order lowpass.  I can model this in Python to see the Bode plot and compare:
import matplotlib.pyplot as plt
G_4=matlab.tf([26826.66,5.7078*10**7],
                        [1.873608*10**-7*np.pi
                          ,0
                          ,4.4415
                          ,9450.0])

print(G_4)

from matplotlib.ticker import FuncFormatter

def units(x, pos):
    if (x < 1000):
        return '%1.1f' % (x)
    elif (x < 1e6):
        return '%1.1fK' % (x * 1e-3)
    else: return '%1.1fM' % (x * 1e-6)

formatter = FuncFormatter(units)

fList3=np.logspace(np.log10(100),np.log10(10000),1000)
wList3=2*np.pi*fList3
mag, phase, omega=matlab.bode([G_4],omega=wList3,dB=True,Hz=True,deg=True)
ax = plt.gca()
ax.xaxis.set_major_formatter(formatter)

My closed-loop bode:

Versus the one given in ADISim:

Not quite sure why my passband gain is so high compared with the ADISim version and why my phase is positive, but they seem to agree on general shape and frequency.


texts: how to see if we got NACK or ACK in I2C efr32fg14

texts:
I need to see if the slave device sends back ACK or NACK in I2C communicaton.in page 515 of the manual bellow i see the I2C_IF register.
bitfield 11 is bushold and it says if the slave holds the line.
How to know if we got ACK or NACK from the slave?
Thanks.
https://www.silabs.com/documents/public/reference-manuals/efr32xg14-rm.pdf


texts:
My circuit need to be plugged into a normal (canadian) 120V outlet.
But everything on it is made to run 5V.

I'm very beginner, so yet, I'm thinking of adding a bunch of resistance, but I feel that it would be a terrible way to proceed ... if it would work, a lot of power would be dissipated in heat.

How do you proceed to lower voltage from 120V to 5V ?

Thanks !


texts: I ordered some (what I thought to be) 1N4148 diodes. However, the part number on the diodes I received reads: 4148ST. I have searched the realms of Google DuckDuckGo, and have found no indications whatsoever on what the ST means. Are the diodes I received 1N41148s? Or are they some other kind of diode that I could not find a datasheet for?


texts: Measuring power consumption / current of an Arduino using a multitester

texts: What is the correct way to measure the power consumption and / or current draw of an Arduino using a multitester?


texts: Does Thyristor (SCR ) works for Inrush current protection?

texts: Does  a SCR ie  Thyristor work for Inrush current protection in a circuit ?


texts:
I'm trying to measure the resistance of a surgical screw that seems to have a low resistance, around maybe one ohm. I use a 1908P multimeter and wires having for resistance around 0.005 ohm.

Since the screw resistance is a small value, I've tried the 4 points measurement method. I get something around 0.3 ohm, but the value changes very easily depending on the orientation of the wires (see below). It goes from 0.3 to 70 ohms.

I'm wondering if it's either my circuit that is wired wrong, the screw because of its properties or if its the lack of precision of the multimeter( it a 5.5 digits) that causes that fluctuation.

Any idea of how I can improve this measurement?


texts:
I need to buffer 1.5Gb/s of video data through SDRAM, which works out to be 3Gb/s total in and out combined.

This is my thinking so far:

Write/read burst length is set to max (16 clock cycles), and CL is 3 clock cycles, that means for every 16 clocks, I need at min another 3. So 19% overhead for just CL between bursts.

Changing banks/rows is another 15 clock cycles (RP + WR + RC). The max number of burst writes I can make without changing rows is 64 (according to the Xilinx spartan 6 MCB user guide page 17). This takes 77 clocks (64 writes of 16 bits * 1.19 for CL overhead) and requires an additional 15 clocks for config (or 20%) between rows.

3Gb/s * 1.19 * 1.20 = 4.28 Gb/s.

I'm considering clocking a LPDDR device at 166Mhz, which gives 332Mhz for both clock edges. If I use a device with a 16 bit word length, i get 332Mhz * 16 bit = 5.3 Gb/s, within my spec quite comfortably.
Perhaps this device?

My main question is: Am I on the right track here? This is the first time I've had to design a board containing SDRAM, do these numbers look right? Is there any way I can configure the chip to further minimize the overhead? Is there anything else I need to consider? The last thing I want is to select a device, build the board and then discover that my choice is too small/slow for my application.


texts: Latches and Two Phase Clocking in modern ASICs

texts: Why are latches and 2 phase clocking schemes frowned upon in modern high speed ASIC design? I understand that single edge flip-flop based designs are easier on STA tools but are there any other good reasons for this bias in the industry?


texts: Mounting battery terminal contacts in an aluminium case

texts:
I'm trying to mount AA terminal contacts in an anodised aluminium case. Given that the aluminium is anodised, does that mean it's not conductive and the contacts could directly make contact with it? If not, what's a good way to mount contacts on an anodised aluminium case?

Thanks


texts: How to Power Arduino and its External Devices with single USB Power Supply

texts:
I’m building a Warning Display with Bluetooth interface. The ‘Bluetooth Module’ and ‘Buzzer Control’ won’t consume much current so decided to connect them directly to the Arduino and they are working fine. But the ‘Lamp Control’ has a lot of LED’s and it needs an external power source. The ‘USB Power Supply’ I’m using is able to source the current required for the ‘Lamp Control’ (and Arduino too).

So this is my plan (see the picture) to wire the ‘Lamp Control’ and everything else.

Info:

Green Lines are Data lines
Red is for +5v
Purple is for +3v3
Black is for GND

The questions are:

Is this OK?
Do I need to connect an extra ground line (Dotted Line?) to the ‘Lamp Control’ for data link?
Or what is the best option to power all these with a single ‘USB Power Supply’?

Thank you, Please help.


texts: How Ix in the give fig. is Zero in 2nd Step?


texts: With Forward Error Correction, what bit rate should be used in a link budget?

texts:
In a typical satellite link budget, you are interested in calculating the Eb/N0, where

Eb = S/R_b (Received power times the bit period) and
N0 is the simply kT (noise power spectral density).

Fundamentally, I have seen two main types of FEC in satellite communications, so let's anchor the discussion in these: 1) Convolutional Encoding, and 2) Reed Solomon Block Coding.
If either one of these two FECs are used, the benefit is simply that you get a coding gain of some dBs, as shown in the figure below. Fundamentally, this is done by adding redundant FEC bits to your raw information bits.

My question is now, when performing a satellite link budget, i.e. when calculating Eb, is it not appropriate to use an adjusted bit rate, that includes the redundant bits, in such a way that the information bits are still transmitted at the same rate. For instance, example calculation below

Information rate (pure information bits) = 1 Mbps
Convultional code rate is 1/2 = > 1 extra redundant bit for every information bit
Reed Solomon "rate" is 255/223 => ca 14.3 % more redundant bits than raw information bits.

Hence, an adjusted bit rate would now be 1×2×1.143=2.286 Mbps. Another reason why I think it makes sense to do this is that you somehow have to "pay the price" of using coding, by increasing the bit rate, you get less energy per bit. But in the end, I would guess the total coding gain, triumphs over the negative effect of having less energy per bit.
I have been unable to find any texts here, and I've seen multiple link budgets do this differently. Hopefully, you understand my question. If possible, please provide a reference. Feel free to correct my terminology as well.


texts: Can I run a 12 volt automobile winch on a 20 volt power supply and how would I caculate if possible

texts:
I have a 20 volt, 90 watt laptop power supply I would like to use to power a 12 volt winch I use to open and close a heavy overhead shop door. The amps drawn are within that provided by power supply.

There is no documentation available for this winch.

A cars electrical system charges at anywhere from 12 volts to 14.8 volts and the 14.8 volts does not seem to adversely affect the winch.

20 volts is only another 5.2 volts above the 14.8 volts provided but there must be some limiting factor. A point where the overvoltage damages the motor after a short time of use, say the time it takes to open the door. I don't want to hit that point.

I realize that more info is needed for a definitive answer but I'm really just asking for a "rule of thumb" type answer and an explanation why this is so.

Thanks


texts: Johnson–Nyquist noise contribution Antenna noise temperatures?

texts:
I understand that for an antenna the greatest contribution to the noise comes from the noise that the antenna captures from the environment, not the "internal" thermal noise of the antenna. But I do not know how to calculate this myself (and prove to myself that the Johnson-Nyquist noise is negligible).

I am imagining a 50 Ohm antenna in a room at temperature \$ T \$, receiving \$ P_{noise} \$ over bandwidth \$ B \$, matched to a 50 Ohm receiver. Hence the noise temperature will be \$ T_n = \frac{P_{noise}}{k_bB} \ne T \$.

However, if the wire making up the antenna has resistance \$ R=1\Omega\$, what happens to the thermal noise power \$P_{Johnson}=k_bTB\$? Is it just mismatched because \$ R \ll 50\Omega\$, and hence not delivered to the receiver?

Similarly, is there a way to express the antenna noise temperature as the sum of a component due to noise received from the environment and intrinsic thermal Johnson-Nyquist noise?


texts: How to specify timing constraint for two paths to have a equal delay in Vivado

texts: I am trying to sample an asynchronous signal in multiple clock-domains. I do not care too much about the absolute delay from the source of the async signal to the sampling FF's, but I want to constrain each of the paths to have roughly equal delays. How would I do this in Vivado/.xdc?


texts: Three phase power supply - what is line to line voltage

texts:
Well this seems like a basic principle, yet I can't seem to get it. (We're expect to "know" this already).

In a three phase situation I'm given a source voltage of 230V. - So the waveform of each of the phases would be: \$ v_s = \sqrt2 \cdot 230 \cdot \sin(\omega t + \theta_i)\$

Where \$\theta_i\$ is \$0, \tfrac{2}{3} \pi,  \tfrac{4}{3} \pi\$  for each phase.

So now I could calculate the line to line voltage by the formula:
$$v_{ll} = 2 \cdot  \left ( \sqrt2 \cdot 230 \cdot \sin(\tfrac{2}{3} \pi) \right)$$

Is this correct?


texts: 3.3V overvoltage limiter circuit topology

texts:
I need to design, using discrete components only, a shunt voltage limiter that drains little or no current (less than 2mA, the lower is better) at 3.3V, and ensure that, when driven at more than 4V, it sinks at least 200mA. No integrated circuit can be used for such purpose (TL431 would solve this immediately). The circuit should remain functional with a delta (positive and negative) of 50°C from the ambient temperature of 25°C and within component tolerances. In addition, the circuit should be kept as simple as possible.

Input parameters:

Guaranteed non triggering voltage < 3.3V
Guaranteed triggering voltage > 4.2V
Clamping current > 200mA

I tried to explore many different options with zeners, resistors, mosfet, bipolar transistors, and compensated transistor pairs, but I was unable to work out a proper solution.

ALD suggests a very simple solution that may fit within requirements by using ALD111933 (http://www.aldinc.com/pdf/VoltageClampCircuits.pdf) however it’s a rather exotic component with a noticeable cost per part.

Can you suggest circuit topologies that could help me to solve the problem?

EDIT:
Some background might be needed to understand the question:

The requirement of not using integrated circuits is related to EN60079 (ATEX/IECEx) requisites. While there might be discordancies about this point, most certification agencies should reject designs where integrated circuits are used as components rated against section 7, even if replicated their fault cannot be countable. This should be the position of most notified bodies, officially endorsed by Intertek (http://www.intertek.com/uploadedFiles/Intertek/Divisions/Commercial_and_Electrical/Media/PDF/Hazardous_Locations/Preventing-Disasters-Through-Intrinsic-Safety.pdf, integrated circuits are assumed to fail in any condition and those faults are non countable).
Why this solution should be technically archiveable is because a similar circuit should be the basis of RS485-IS protection circuit described here: https://www.profibus.com/download/profibus-rs485-is-user-and-installation-guideline/ in order to archieve a Uo of 4,2V with a 3,3V transceiver, there must be a similar voltage clamp. Note that if all 32 transceivers on the network would sink 20mA per diode, the power supply should be capable of sourcing nearly 2A just for the protection diodes. Or, each of the circuits should include a DC/DC to avoid overloading the bus).


texts:
Is there any rule-of-thumb for choosing amplifier wattage for the given speakers wattage?

For example, I have speakers, 100 W (max. input power) / 6 Ohm each. Is it ok to match them with 44 W (min. continuous power) / 8 Ohm / channel?

In general, is it ok to hook up large speakers to weak amplifier? Is it ok to hook up small speakers to powerful amplifier?

I've read that speakers should be able to handle twice the wattage of amplifier output. True?


texts: Make a caption n a copper layer in eagle

texts:
Read all the internet but cannot find how to make a caption on the copper "ratsnest" (either top or bottom) in Eagle. I want to make it "negative", i. e. no copper where letters are supposed to be. Now then I add the caption to the top or bottom layer, eagle makes a no-copper square and puts a copper caption inside (copper is brown):

But I want it to be like this:

The question is how to do that?

Tried to put the caption on the keepout and restrict layers. In case I set it to the "restrict" layer, just the empty box is drawn without any copper including text itself:

In case I set it to the "keepout" layer, nothing happens:

Please help. Thank you.


texts: Why use 100E resistor in max232 ic in serial pins 13 and 14?

texts:
serial pin 13(RxD) use 100E -pin 13 to male connector pin 2(RxD),
serial pin 14(TxD) use 100E -pin 14 to male connector pin 3(TxD)

Why 100E used?

I have attached image and mention clearly for your reference...


texts: I feel silly asking this question but I am mystified. I can't seem to tin the 24 gage stranded wire used in Christmas tree lights. I've tried every kind of solder/ soldering iron combination I have , even tried various paste fluxes, all to no avail. The solder wont wet the copper. Am I looking at an oxidation problem?


texts: EEPROM I2C driver hanged during ESD test?

texts:
In our prototype , we have a I2C based EEPROM . During ESD Test(High potential spark is injected into system for a very short moment), the drivers hangs in the I2C code.

Basically there are while loops in which which we are checking is the busy , or transmit flag is set or not, Acknowledge received or not using the respective registers.
So , if any of the parameters is not matched , then the code will hang in that loop itself.

This driver works fine in normal conditions.

But during spark injection, it hangs in one of the loops.

And even after the ESD test it remains in the same condition, , it does not recover until we restart the device.

What could go wrong with the controller(MSP430F6438 I2c bus) or the slave(I2c based EEPROM), which causes the code to hang in one of the loops which checks for busy bus, transmitt flag, acknowledge recieved flag?


texts: Accessing CPU registers while in reset using DSTREAM & DS5

texts:
The problem I currently have is that I wish to test SecureBoot on a device without permanently modifying a set of internal security registers with computed hash information. The way the documentation suggests you do this is to load a modified reset configuration blob such that execution gets "held off" at boot time. This gives you enough time to use JTAG to set the registers of interest before manually releasing the CPU.

However, my problem is that while the CPU is in reset I am not able to connect to and read register values. The JTAG device I am using is the ARM DSTREAM along with their DS5 development environment. While in reset the toolset identifies the device to be "held in reset" but all attempts to use the "memory browser" feature returns no results.

This works fine, of course, if the CPU is first in a running state and I manually interrupt execution before attempting to read memory.

tl;dr

Can register values/memory content of a CPU be read over JTAG when the core is held in reset?

EDIT

Some of the specifics behind how to configure the device to hold-off at boot are very specific to this device, but the cores are held in a reset state when enabled. The SoC is a QorIQ LS1043A by NXP. This chip is a quad-core variant of the LS1021, which has an application note for this here. The reference to enabling the hold-off state are stated as setting BOOT_HO=1 in the reset configuration word.

All I see when trying to read from memory while the cores are held in reset is the following, regardless of the address being read:


texts: How do I calibrate an AVR's RC oscillator using the UART?

texts:
I would like to set my AVR's OSCCAL for proper RS-232 communication using the other end's transmission as the calibration clock, without having to solder the RX pin to a timer pin. Is there firmware to do this?

edit
I wound up writing my own synchronization routine and soldering the RX pin to the ICP (input capture) unit. When the ICP pin changes, TIMER1's value is copied into a register and an interrupt fires.

The code uses an ADCPM-inspired search technique. OSCCAL is incremented or decremented by 1 initially. Each time OSCCAL needs to move in the same direction again it moves twice as far, when it switches direction it starts over at 1. http://code.google.com/p/pwmsign/source/browse/synch.c

All that trouble, and I discovered the perfect OSCCAL was only 1 off from the factory setting.


texts: What would a transistor level design of an XOR gate look like?


texts: Microcontroller PWM to bipolar push-pull amplifier issues. (level shifting)

texts:
I'm trying to design a circuit that allows a micro controller (arduino) to control a voltage to a load. The load voltage needs to be bipolar in nature (+- 3 to 5 V) for use in controlling a TEC.

My current design idea is to take the output of the micro controller as PWM and lowpass filter it to obtain a voltage between 0 and 3.3 V. From there, I plan to level shift it to +- 3 V via input to a BJT as shown below:

simulate this circuit – Schematic created using CircuitLab

When this portion of the circuit is tested alone, it appears to deliver the correct characteristics (50% PWM duty cycle gives 0 V, the average of many switches between + and - 3 V, varying the duty cycle increases/decreases this voltage up to the supply rail voltages in a proportional manner).

From there, the input is fed into a simple push-pull amplifier topology feeding off the same bipolar supply as the level shifter, to drive the load (load current in the region of 1 Ampere desired).

simulate this circuit

When the level shifter and low pass filter is connected to the push-pull amplifier, it becomes loaded and does not give the desired proportional voltage control I am after. I've tried moving the lowpass section to before and after the level shifting transistor, but in that configuration I have difficulty driving enough current through the base of the transistor to get it to switch (current amplifier needed?).

How would I best go about resolving these issues with the given (rough) topology? I've considered using an op-amp as a buffer for the low-pass stage, but I've only access to 741s which won't do for the +- 3 V power supply (Maybe I could increase the supply voltage - the driven load is a TEC device).

Is it possible to buffer the lowpass section output with a transistor simply? Or do I move the lowpass section to before Q1 and somehow build a current amplifier?

Any input or suggestions on overcoming this problem would be much appreciated, thank you.

I have access to only a single bipolar bench power supply and BJTs (no FETs, unfortunately) (along with some LM741 op-amps, and a selection of resistors, capacitors and inductors, but nothing fancy or integrated (might be able to squeeze some 7400 series logic AND gates for doing cheap level shifting if required).

Please note, the component values used in these schematics are for rough description only.

I've implemented Spehro's buffer suggestion, and it appears to be working as desired. Can anyone make any suggestions as to how I could further improve this circuit? (Q1 current seems a little high, ~100 mA, but only 75 Ohm on the collector seems to bias the RC lowpass output to around 0 V at 50% PWM duty)

The circuit is drawn up in LTSpice for simulation here.

Below is the circuit drawn up in CircuitLab, if that's easier to see.

simulate this circuit

Update: I've added some biasing resistors to the emitter-follower section and tweaked stuff a bit in LTSpice in order to get the system as linear as possible from the PWM input to output. I'm not quite sure if what I'm doing is correct, but it seems to be better than what I've been doing before.

LTSpice circuit linked before has been updated to match if that's easier to simulate.

simulate this circuit


texts: Thermocouple to ADC - with negative and positive voltages

texts:
I am trying to interface a K type thermocouple to the ADC channel of a Microchip part.

I am interested in negative (to -2mV) and Positive ( to + 4mV) voltages but don't know how to feed them into the ADC to get the full 12 bit resolution over this range of input voltage.

I realise I need to amplify the output from the thermocouple and yes, I know all about cold junction compensation etc.  I just need some ideas of how to interface the -2mv to +4mV signal into the ADC.

Thanks in advance


texts: Why is the voltage across a reverse biased diode equal to source voltage?

texts: Why is it not equal to zero since a reverse biases diode is essentially an open circuit?


texts: What happens if we swap these two components?

texts:
So, in what looks like an attempt to explain mesh currents, my book has the following diagram:

Then it proceeds to convince us of the veracity of several equations.  The first of them makes sense: \$i_d=i_1-i_c\$.  The signs are preserved by the pattern in the use of current directions.  Okay, I get that.  Then it says something a bit harder to grasp: \$i_g=i_3-i_2\$ and \$i_f=i_1-i_3\$.
So my question becomes:  What happens if we flip f and g?  It seems that \$i_d=i_e\$ regardless of the chirality of the components, all of the numerically indexed currents are going to be the same.  How, then, can these relationships be demonstrated?


texts: Attenuating a 10V Sin wave [Circuit design]

texts:
About a year ago I designed a circuit that takes a 10V analogue signal and converts it to a 5V level and gets read by an ADC etc.

Here's the original circuit:
The AD620 has external pins for a single gain resistor, it has a gain of 1 in the circuit

simulate this circuit – Schematic created using CircuitLab

I've decided to revisit some of my old designs and was finding ways to improve upon what I previously built.

With input limits of 0V and 10V my clamping diodes aren't needed at all, as the maximum limits I get after the voltage divider are 0V and 5V anyway.
I buffer the singal, divide it down and then buffer it again which I think could be better implemented
There is no impedance matching on the input of the AD620

I've redesigned the circuit and removed some components and added another resistor on the input and have come up with the following circuit

simulate this circuit

My signal source can supply 150mA so shouldn't have a problem driving the low impedance resistor.

Question - I guess my actual question is this, are these two circuits comparable? Or are there any better solutions?
Any other feedback or issues you see with either of my designs feel free to point out.


texts: Gerber viewer confusion - missing traces

texts:
I'm not sure about my gerber files. I guess there is something wrong.
In different gerber viewers the PCB looks right. But in online viewers from JLCPCB and PCBway, the bottom view looks wrong. Some traces are missing.
Bottom layer (everything is there):

Bottom view (some traces are missing):

Where are the missing traces? It's only a 2 layer board. And all traces are displayed in the bottom copper layer, but not in the bottom view. The top layer looks fine. I don't understand this.


texts:
The above problem was asked in GATE 2018 Electrical paper. I got the answer as 50. But I am confused if my answer is correct. The funny part is all top 3 coaching institutes has given 3 different answers for this problem. Please help me with this problem.

Solution by Kreatryx

Solution by Made Easy

Solution by ACE Academy


texts:
If our hand is near the infrared sensor, it will remain in HIGH condition until we release the hand from the sensor.
How can an additional circuit (without a microcontroller and without another ne555) with the sensor input when the circuit conditions when the sensor is HIGH,  produce output on the additional circuit HIGH and immediately LOW again without having to change the condition of the sensor output which is still HIGH.
The plan is to make the ne555 timer input because of this. If the trigger input continues on (sensor), the ne555 can't start counting the timer
In PLC what I mean on my thread is a one-shot block, what does it mean is when the input is HIGH, the output is also HIGH but immediately LOW... maybe is like pulse current. because on my timer input(ne555) the timer cannot start counting if my input from sensor is still HIGH... i have an idea to make a one-shot-like circuit to make it happened


texts: Help identifying a photodiode pre-amp PCB

texts:
Recently I found this PCB in a electronics junk bin. It's said that it's a photodiode preamp, but I was not able to find the datasheet or any information about the board.

Since the PCB looks neatly designed and put together I wanted to know where this PCB could have been used for.

Would also be interesting to find the IC's that are missing and test the functionality.


texts: ATmega: Can one determine if an address is program memory or data memory?

texts:
On an Atmel ATmega1284 (or any of its AVR cousins), is there any way to determine at compile time or at runtime whether an address that is passed to a function belongs to program memory space or data memory space?
Specifically, I want to provide a debug trace where the input string may be stored in program memory space or in data memory space, but I prefer to use just one function for it so the caller doesn't need to bother: if the input string is stored in program memory, I can copy it to a stack-allocated buffer and then pretend it was always in data memory. For example, in C-like pseudocode:
function my_trace(const char *string) {
    if (is_in_program_memory_space(string)) {
        strcpy_P(local_buffer, string);
        print_the_(local_buffer);
    }
    else {
        print_the_(string);
    }
}

const char data_memory_string[] = "data memory string";
const char program_memory_string[] PROGMEM = "program memory string";

my_trace(data_memory_string);
my_trace(program_memory_string);

I tried to put in a breakpoint in the compiled code and it seems the addresses of a data-memory–allocated string and a program-memory–allocated string happen to be very close (like 0x800040 versus 0x800360) so I can't rely on address ranges. (And, doing that would probably be unsafe anyway, but that's a different discussion.)
Edit: I'm using the toolchain that comes with Atmel Studio, which in this case is version AVR_8_bit_GNU_Toolchain_3.6.2_1778.
Edit 2: The solution provided by user @NStorm indeed solves the problem. However, on my system it was necessary to typecast the return value of __builtin_avr_flash_segment() to a signed char.


texts: ATtiny2313 vs ATtiny84 software compatibility

texts:
I make and sell a variant of the USBtiny AVR programmer. It uses an ATtiny2313 clocked at 12 MHz and does bit-banged USB using hand-tuned assembly language (that someone else wrote - it's an open hardware / open firmware project).

In an attempt to reduce costs, I'd like to shift from using the 2313 to using an ATtiny84 instead.

I can figure out how to adjust the firmware for the different pins. But the big(ger) question is whether that hand-tuned assembly language will run the same way on the 84.

Other than pins and registers, is the entire ATtiny chip range cross compatible from a software perspective otherwise?


texts: Connect audio output to recording device

texts:
I am working with the 9V sound recording module from Radio Shack. It comes with an electret mic, but I am trying to figure out how to connect headphone output or computer line out output to the mic wires (if possible)

Link to device on Radio Shack's Web site

When in recording mode, the voltage to the mic seems to be about 3.3 volts.

Is there a circuit to make this connection and have sound files 'played' to the sound module from an mp3 player, for example?


texts:
I have a circuit where an 12 bit ADC IC is outputting 5V logic levels, which are going to be read by an FPGA inputs. The FPGA voltage is 3.3V so the 5V outputs from the ADC chip will switch the 3.3V to the FPGA through opto-couplers.
I am using ILD74 opto-coupler IC's and have attached it's datasheet. It is uses NPN transistor outputs.
My question is what will be the voltage dropped across the collector-emitter of the NPN transistor? Can I expect it to be approx 0.6V?
The reason I ask is that I can't lose the 0.6V from the 3.3V input to the FPGA. Also the FPGA inputs are pulled down with resistors so I want the inputs to be active high.
Thanks everyone!
ILD74 datasheet pdf
EDIT
I am just thinking, would it be a better idea to connect the 3.3V FPGA inputs on high side switching and let the opto-couplers do the switching so the FPGA has a strong 3.3V and 0V levels. And then just invert the 12 bit inputs on the FPGA hardware?


texts: Are some soldering iron tips unsuitable for lead-free solder?

texts:
I don't do much lead-free work at all, so I'm asking this question out of ignorance. I have been using leaded solder as long as I have been soldering, and I have never had an issue with a soldering iron tip. The plated part of the tip always stays shiny, I'm OCD about cleaning the iron, careful with the temperatures used, and never leave my iron on long without using it.

I went to borrow an iron from a lab, and the tip was dark grey and rough. It would not accept any solder unless I tried to rub off some of this material, and even then it would only be a small spot that oxidized very quickly. I concluded that the tip was ruined, and went to get another iron with a better tip, but all the irons in that lab had the same condition, or worse. I got a brand new tip and installed it, and the tip lasted for about 15 minutes before it had a perfect coating and could not be cleaned. This whole time, I had been using the available solder: a 99.3% Tin, 0.7% Copper blend with a rosin core.

To further the ancedote, I came across another lab that used the same iron, but only had lead based solder. The tips in this lab ranged from perfect to moderately abused, but all would have been able to easily melt solder. Many irons were set to 450 degrees C, and their tip looked just fine. I'm not sure how much I would trust the temperature though, the iron is just about the cheapest "temperature controlled" iron I've seen.

Taking another new tip and using lead based solder, I was able to end up with a tip that I would classify "used, in good condition" after a soldering session. My conclusion is that the lead free solder is either more corrosive or less protective than normal lead solder. Which (finally) leads to my questions:

Is there a lead free metallurgy that is more forgiving to soldering iron tips?
Is there something inherently wrong in my handling of the soldering iron?
What would I need to solder with this composition?
Is there any hope for these tips that have been used with the lead free stuff? (My gut says no)

The soldering iron is a Stahl Tools SSVT Variable Temperature Soldering Station.

The solder is Elenco LF-99: 99.3% Sn, 0.7% Cu; Rosin core.

EDIT:

The other oxidized irons used were used to assemble simple kits; nothing very fancy or exotic as far as I know. They were handled by novices, which made me originally believe that the students had destroyed the tips. When I ended up with an oxidized tip that was otherwise clean, I thought it was less likely that the students had killed the iron. As I was using the lead-free solder, applying solder never seemed to clean the tip. I wasn't setting the iron to temperatures that were excessively high in my opinion (400 degrees C), but I don't know what the actual temperature of the iron was.


texts: DC current continues measure using shunt resistor with ADS1115 and ESP8266

texts:
#include <Wire.h>
#include <Adafruit_ADS1015.h>
Adafruit_ADS1115 ads; /* Use this for the 16-bit version */
void setup(void)
{
Serial.begin(115200);
ads.setGain(GAIN_SIXTEEN); // 16x gain +/- 0.256V 1 bit = 0.125mV 0.0078125mV
ads.begin();
}
void loop(void)
{
int16_t results;
results = ads.readADC_Differential_0_1();
Serial.println(results);
Serial.print("Amps: ");
float amps = ((float)results * 256.0) / 32768.0;//100mv 100A shunt
amps = amps * 2.666; //uncomment for 75mv 200A shunt
Serial.println(amps);
delay(300);
}

Is this correct? Because i didn't get real values. I'm using shunt resistor which is 200A 75mV drop. i have esp8266 and ADS1115 to measure the small voltage drop of the shunt.ACS712 hall sensor gives me terrible experience. I'm trying to monitor my solar panel DC current on Blynk App. My plan is to develop DIY smart charging controller which can get maximum efficiency from my panel and get data to a online dashboard.


texts: Telephone Call and Electromagnetic Waves

texts:
Can you give me a simple explanation of how do telephone calls work?

I know that when I receive a telephone call, it means that my mobile has just received a certain Electromagnetic field. But in air there are many electromagnetic fields, which correspond to all the telephone calls directed to other numbers. How do my mobile phone understand which is the correct Electromagnetic field? What is the role of the sim card on this?

I think that the receiver antenna of a mobile phone will receive all the electromagnetic fields in the air, and all of them will generate some voltages on it.


texts: Transient Current in an LC circuit with a DC supply

texts:
Here is a LC circuit with a DC supply.

When the switch is closed at t=0 capacitor behaves as a short circuit while the inductor behaves as an open circuit as the voltage across the inductor immediately jumps to battery voltage.

Now we know that the current in inductor increases while in a capacitor current exponentially decreases with respect to time.

I wonder then how the current will overall behave in that circuit as when capacitor is short circuit inductor is open circuit at t=0 then when current in capacitor decreases then at the same time in inductor it is expected to increase. So what will be the overall shape of the current with respect to time. How will its graph look like and whats the theoratical explaination for that ?


texts: I have an IC (PDIP) I would like to replace with a board and some smd parts. Normal 0.1" headers are too thick to fit in the holes of the desoldered IC pins. Do you know if there exists 0.1" pitch headers with diameter of 0.6mm or less, so that they fit in the holes for the IC pins?


texts: How to represent a given sinusoidal equation?

texts:
I'm having problems figuring something out, and I'm sure someone can guide me in the right direction here.

Write the sinusoidal equation and then represent it for the voltage u(t) if T=2 [ms] and the peak value Um = 331 [V] is reached at t= 0.2 [ms].

I know that the sinusoidal form for the voltage is:

\$u(t)= U_m  \sin(\omega t + \gamma)\$

I also calculated the frequency f = 1/T = 500 [Hz]

\$\omega = 2  \pi  f = 1000\pi\$

So basically my equation becomes this:

\$u(t) = 331  \sin(\frac{2\pi}{10} + \gamma)\$

My questions are the following:

Do I need to find out the value of "γ"? And if yes, how exactly am I supposed to do that?
How do I represent this equation graphically?


texts: 12VDC 3-Position Axial/Rotating Connector

texts:
I am looking to source a connector suitable for use in a 12VDC light. I need to assemble/disassemble the 3 components- a base, stem and head.
The 'tricky' part is that I also want these connectors to be the rotating points for adjustment so they must be able to rotate around a central axis (much like a normal DC barrel plug can). I don't expect the mechanical strain to be be taken by the connector, I can design load-bearing shoulders etc. for this.
The connector must also be 3 position- I have seen DC jacks with a sense pin, normally for laptops but I don't know how good these are for a reliable contact if the part is occasionally rotated?
I have also thought about slip rings but the problem is I want the two parts to disconnect.
Lastly I was thinking about 3 position/TRV audio jack plug connectors? 6.35mm/0.25" would be great as long as I can get a female jack that's small enough to fit inside a Ø12mm tube.
Any ideas or words of caution would be appreciated. It would likely need to be rated 3A or above and I will be over-moulding the connectors.
Thanks!


texts: Trace impedance on 4layers (Top and internal_plane_1)

texts:
I'm currently design a 4layers pcb with 50r trace for an Ceramic chip antenna (on top layer).
Due of a lot of trace, my trace antenna is a coplanar.
Trace on top layer with polygon pour around AND internal_plane_1 (just below) connected to gnd.

The calculation: [https://chemandy.com/calculators/coplanar-waveguide-with-ground-calculator.htm[1
With E = 4 / S = 0.37 / W = 0.154 / h = 0.2.
Impedance >> 50.0r

My question. We see often impedance controled track with Top and Bot layer, rarely with top and internal plane.
is there a contraindication ?


texts: Arduino LED matrix and 2D array, data seems to be corrupting

texts:
I'm trying to drive an 8x8 LED matrix with an arduino nano, but I can't get the LEDs to display what I tell it to.

I'm using this LED Matrix

Here's my code:

int row1 = 2;
int row2 = 3;
int row3 = 4;
int row4 = 5;
int row5 = 6;
int row6 = 7;
int row7 = 8;
int row8 = 9;

int col1 = 10;
int col2 = 11;
int col3 = 12;
int col4 = 18;
int col5 = 14;
int col6 = 15;
int col7 = 16;
int col8 = 17;

void setup() {
  int i;
  for(i = 2; i <= 18; i++) {
    pinMode(i,OUTPUT);
  }
  for(i = 2; i <= 9; i++) {
    digitalWrite(i, HIGH);
  }
}

void loop() {

  int display [8][8] = {
  {1,0,0,0,0,0,0,0},
  {0,1,0,0,0,0,0,0},
  {0,0,1,0,0,0,0,0},
  {0,0,0,1,0,0,0,0},
  {0,0,0,0,1,0,0,0},
  {0,0,0,0,0,1,0,0},
  {0,0,0,0,0,0,1,0},
  {0,0,0,0,0,0,0,1}
  };

  updateScreen(display);
}

void updateScreen(int screen[8][8]) {

  Serial.begin(9600);
  int i;
  for (i = row1; i <= row8; i++) {
    Serial.println(i-1);
    digitalWrite(i, LOW);
      digitalWrite(col8, screen[i-2][0]);
      Serial.print(screen[i-2][0]); Serial.print("|");
      digitalWrite(col7, screen[i-2][1]);
      Serial.print(screen[i-2][1]); Serial.print("|");
      digitalWrite(col6, screen[i-2][2]);
      Serial.print(screen[i-2][2]); Serial.print("|");
      digitalWrite(col5, screen[i-2][3]);
      Serial.print(screen[i-2][3]); Serial.print("|");
      digitalWrite(col4, screen[i-2][4]);
      Serial.print(screen[i-2][4]); Serial.print("|");
      digitalWrite(col3, screen[i-2][5]);
      Serial.print(screen[i-2][5]); Serial.print("|");
      digitalWrite(col2, screen[i-2][6]);
      Serial.print(screen[i-2][6]); Serial.print("|");
      digitalWrite(col1, screen[i-2][7]);
      Serial.println(screen[i-2][7]);
      delay(1);
      blank();
    digitalWrite(i, HIGH);
  }

}

void blank() {
  digitalWrite(col1, LOW);
  digitalWrite(col2, LOW);
  digitalWrite(col3, LOW);
  digitalWrite(col4, LOW);
  digitalWrite(col5, LOW);
  digitalWrite(col6, LOW);
  digitalWrite(col7, LOW);
  digitalWrite(col8, LOW);
}

And here is the output:

1
1|0|0|0|0|0|0|0
2
0|1|0|0|0|0|0|0
3
0|0|1|0|0|0|0|0
4
0|0|0|1|0|0|0|0
5
0|0|0|0|1|0|0¾j
6
0|0|0|0|0|1|0|0
7
0|0|0|0|0|0|1|0
8
0|0|0|0|0|0|0|1

So I can tell that the error (probably) isn't my wiring, because those array values are clearly wrong, I have no idea where the ¾j is coming from.


texts: MOSFET overheats and results in short circuit

texts:
I use this 40V, N-Channel NexFET Power MOSFET
http://www.ti.com/product/CSD18504Q5A

in

simulate this circuit – Schematic created using CircuitLab

The solenoid takes 25A peak current. (Rated drain current is 50A)

In this setup, MOSFET overheats and shorts after some time.
What is wrong with this setup? Please advise.

P.S. I am a noob.


texts: VHDL inout port instantiation vector to single bit inout ports

texts:
For a hardware FPGA project, I like to name my top level VHDL ports exactly the same way as they appear on the PCB schematic. This creates a little bit of a problem when an internal entity instantiation has inout ports defined as vectors (and the entity was auto-generated, so I can't just expose an in/out/tri-state port). I'm trying to verify whether this is a valid way to map the inout std_logic to a inout vector port. See example and attempted solution below:
library ieee;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;

entity top is
port (
        CLK : in std_logic;
        I2C0_SDA : inout std_logic;
        I2C0_SCL : inout std_logic;
        I2C1_SDA : inout std_logic;
        I2C1_SCL : inout std_logic
);
end entity top;

architecture behavior of top is

  component InnerEntity
  Port (
        clk  : in std_logic;
        vect : inout std_logic_vector ( 3 downto 0 )
  );
  end component;

  signal inoutVectAsSignal : std_logic_vector(3 downto 0);

begin

    InnerEntity_inst : InnerEntity
    Port Map (
        clk    => CLK   ,
        vect   => inoutVectAsSignal
    );

    --Drive inout vector with inout bits?
    inoutVectAsSignal(3) <= I2C0_SDA;
    I2C0_SDA             <= inoutVectAsSignal(3);

    inoutVectAsSignal(2) <= I2C0_SCL;
    I2C0_SCL             <= inoutVectAsSignal(2);

    inoutVectAsSignal(1) <= I2C1_SDA;
    I2C1_SDA             <= inoutVectAsSignal(1);

    inoutVectAsSignal(0) <= I2C1_SCL;
    I2C1_SCL             <= inoutVectAsSignal(0);

end architecture;


texts: Turning a PMOS Common Source into a Voltage Follower

texts:
So I have this PMOS Common Source. I thought I'd make it a Voltage Follower by simply pulling it down to ground. But when SPICE-ing, whatever value the pull down resistor I give, it just won't work as a Voltage Follower.

Is it maybe because the V_in is ideal and assumed to provide the expected voltage no matter how much current is drawn out of it?

simulate this circuit – Schematic created using CircuitLab


texts: Does this RGB LED really need 220 ohm resistors per color?

texts:
I have an arduino kit (5v) and instead of just following their simple instructions I want to know why they are using certain resistors for their RGB LED's.

The RGB LED that comes with this is identical to this one. And I'm assuming the forward voltage and current is the same.

The directions call for three 220-ohm resistors, but is that necessary? My math tells me that Red needs a 100-ohm and the Green & Blue need 160-ohm's. Won't using more resistance decrease the luminosity of the LED?

Or maybe the resistors have something to do with the affect they are trying to achieve with the LED? Here's what the book states, which I don't really understand:

  "By creating a voltage difference between the cathode and voltage
  coming out of the Arduino's PWM pins (which are connected to the
  anodes through 220-ohm resistors), you'll cause the LED to fade
  between its three colors."

Do the resistors have anything to do with this fading, or isn't it just the PWM controlling that?


texts: Analogue switch TS3A475 does the direction matter?

texts:
Does the "direction" of the signal matter?

signal is 1/3Vcc to 2/3Vcc


texts:
As per the datasheet of STM32F103C8T6, its GPIO pins has a hardware speed limitation of 50MHz. I need to achieve speed above 10MHz, but even with assembly codes I am getting only 7.99MHz.

It is running at the maximum recommended speed of 72MHz (8MHz Crystal + PLL).

Can anyone guide me ? Please check the following assembly language loop I am using for toggling the GPIO pins.

 asm(".equ GPIOB_ODR, 0x4001080C");
 asm("ldr r6, = GPIOB_ODR");

 asm("loop:");
 asm("mov r1, #0xFFFFFFFF");
 asm("strh r1, [r6]");
 asm("mov r1, #0x00000000");
 asm("strh r1, [r6]");
 asm("b loop");


texts: Circuit schematic in Eagle seems to connected in series in board layout

texts:
I am very new to Eagle. I was drawing a schematic that would connect my AVR Dragon to my Atmega32A. I drew this up and switched to board layout.

The problem is in board layout. It seems to me that VCC is connected in series from the square pad -> 10k resistor, pin30 -> pin10, C1 (0.1uf) -> C2 (0.1uF) The square pad (for VCC) is outside the drawing board to the left. I was certain that these are supposed to be connected in parallel. I apologize if I am missing something here but I do not see any thing wrong with my schematic. Please correct me.


texts: Driving many leds from 9V battery and USB wire

texts: Hello I have 45 10mm Ultra Bright 7000mcd LED's with a Forward Voltage of 3.2 - 3.6 that have a Maximum Current of 20mA Max of 50mA peak for 10% Pulse Width. that came with 50 1/4W 100 ohm Resistor, and 50 1/4W 470 ohm Resistor. what exactly are my options? I would like to run as many as possible off of one 9V battery if possible. and I would like to do the same (run 45 LED's) off of a 5V usb wire if possible. can you help?


texts: Powering an External Phone Ringer - Straight Talk Home Service

texts:
My dad is having difficulty hearing his cordless phone ring in his shop, due to ambient noise. He has the phone connected to a Straight Talk home phone service device. So, there is no legacy analog line. I am trying to drive an external ringer that was built for an analog system. The Straight Talk jacks do not output sufficient current to drive the ringer.

Is there a way I could use a ring detector and relay? Does anything exist? How difficult would building something be? I have read that the old ringers require 90 VAC. Is that correct?

Sorry. Lots of questions in one post.

Thanks in advance for any info, ideas, suggestions, etc.


texts: If two objects are grounded, why do they still need to be bonded? And if they are bonded, why does each still need to be grounded? (fire safety)

texts:
When transferring a flammable liquid, both the container and the receptacle are supposed to be grounded and bonded.

If they are both grounded, shouldn't the change on each be equal to ground? And if so, why do they still need to be bonded?
And similarly, if they are already bonded, then there shouldn't be any sparking when the come in contact. So why do they still need to be grounded?


texts: Cross-Talk/Interference between UART Lines on a PCB

texts:
I am wondering at what distance UART lines begin to interfere with each other?  And can I expect the UART lines below to function properly?  The PCB board below has 6 UART lines running alongside one another (the purple traces).
Some info about the PCB below:

The purple traces are approximately 1mm apart 0.25mm lines.  Except
when red UART  lines run directly above purple lines.  A ground
plane is in-between though.
4 layer PCB top layer, inner1, inner2, and bottom are signal (red),
ground, signal(purple), power planes respectively.
All planes are filled with a ground layer around the traces.
The UART lines are at 1.8V.

A close-up


texts:
Take for example a Siemens S7 24V digital input.
I read a couple of articles and also questions on SE and it seems there should be (maybe integrated, maybe as a discrete part):

optocoupler to electrically isolate
TVS diodes to shunt/clamp spikes
surge resistor to limit inrush currents
capacitor to absorb spikes

Is this correct?
How is an industrial 24V SPS input protected?
What protection and in which order would this input have?
Does somebody have an layout of such an input to study?


texts:
I am trying to simulate a LNA circuit from the book "Design of CMOS RF Integrated Circuits and Systems"

However, the LNA circuit still does not give POSITIVE GAIN.

Any help ?


texts: How to attach a paper screen to a DIY PCB?

texts:
For poor people who can only afford paper and not silk, a home brew silk screen can be inkjet printed onto paper and then glued onto a PCB.  Component legs will be poked through the paper.  So I have a PCB like:-

and want to add my paper screen like:-

The large multi pin package towards the middle is digital, clocked at 16MHz.  There are also some analogue voltages about in the mV and kHz ranges.

Photo mount type stuff is my instinctive choice of glue, but might there be issues with capacitance /resistance?  What type of adhesive might be suitable to glue the paper to the PCB?  Is there an electronics glue?


texts:
Logic Gate using Transistor and Diode not working on Proteus, just show ON light different on MultiSims is always work as the Logic Gate's Schematic.
For example Logic NOT :

PROTEUS just Light "ON" never show "OFF" at "NOT Logic Gate".
Please help me What the best schematic for Logic Gates only use Transistor and Diode without IC 7400 etc can work as good as Multisim.


texts:
I have a schematic which is provided between the images. I was searching Google with no luck finding what does +Vs and -Vs mean. Also, on the schematic is a weird μP square. Even the guy in my local electronics couldn't identify it. Could someone explain these things for me?

Thanks.


texts: Transfer function of Operational Amplifier

texts:
I am trying to solve the following operational amplifier circuit to get its transfer function.

I have tried two different approaches, one is elementary approach by finding V- and V+ and equating them. But problem with this approach is that the equations are extremely complicated as there is another node (Va) which has both variables V- and V+. [Applied Milmann's Theorem on these three nodes to get the expressions of voltages]

The approach I tried is to write an equivalent circuit of op-amp and then writing conductance matrix and applying Cramer's rule to solve the matrix. But, in this approach also as I apply conditions for ideal op-amp equations are not solvable.

I am looking for a simple way to approach this problem.

NOTE: G's are all conductances.


texts:
I'm synchronizing two FLIR cameras and FLIR's use of opto-isolation in this document doesn't make sense to me.  Could someone explain the benefits of using opto-couplers as FLIR describes?

The two cameras are both connected to one computer via USB3.0 cables.  In order to synchronize the cameras, a 6-pin GPIO cable is used to connect the two cameras directly.  One of the cameras is configured as "primary" and is triggered to capture images by software on the computer.  The other camera is configured as "secondary" and is triggered by the "primary" camera through the GPIO cable.

This is the pinout for the GPIO port coming out of each camera.

And this is the cable wiring diagram to connect the cameras together.

I feel like I just wouldn't have done it this way, but that doesn't really matter.  Could someone explain to me why they did do it this way?  At the very least, this setup creates a ground loop between the 2 USB cables and the 1 GPIO cable.  I would think that the opto-isolation would be used to prevent exactly this.  Could someone elaborate?  Thanks


texts:
Quick, and potentially silly question.

I'm working on an old board design (late 70's) that utilizes a 6800 processor. The current board design left a few address lines from the CPU unused. I'd like to utilize these in a new board design.

However, in order to do that, I need to introduce a CPLD between the CPU and ROM (EPROM). The CPU runs at 850khz, and while that's pretty slow, I figured that before I worried about programming a CPLD, I'd ask this -

Could a CPLD inline between the CPU and ROMs, adding between a 7ns and 25ns delay adversely affect the CPU running at that speed?

I want to say no, but thought I'd check.

Edit Notes: Bus speed should be the same - HOWEVER, a PIA interrupt is connected to a 555 timer that should run at 450khz, regardless of the CPU's frequency. The CPLD will be replacing the other logic gate chips, and be connected directly to the CPU address lines and the EPROMs address lines. So any delay would be limited to the CPLD, not added on to other logics. EPROM speeds will range between 70ns and 200ns. (My new design will allow the current 2732 EPROMs to be switched out with newer EPROMs and Flash chips. I guess the flash chips could be faster - but I doubt that would be an issue.)
I unfortunately can't post a schematic, as I'm not finished with it yet. :)

--Mike


texts: How do I use command line to compile Libero SoC projects?

texts: I want to use a shell script to compile my Libero projects. How can this be achieved? If anyone has done it, please let me know. The documentation from Libero is not very helpful at all.


texts: Clock line of SDIO bus has worse rise/fall time than rest of bus

texts:
I have an ATWILC3000 wifi module connected to a Raspberry Pi Compute Module 3+ over 4-bit SDIO. It's throwing a lot of bus errors at higher frequencies (currently running at 1 MHz for stability when it should be closer to 50 MHz). In probing the bus, I found that the rise/fall times of the clock line are substantially worse than the data lines in violation of the 5ns maximum specified by Microchip for the clock. Shown below is the (presently 5 MHz) clock on scope CH1 (yellow) and D0 on CH2 (green):

I can't seem to figure out why the clock line would be loaded down more than the data line, especially to that degree. Here's what I've looked at so far:

My oscilloscope probes are both set to 10X (10 Mohm/15 pF).
The issue is consistently on the clock line if I swap scope channels.
The rise/fall time numbers don't seem to change much at all as I vary the bus frequency in the OS config.
I have not looked at the CMD or other data lines yet.
The PCB is designed for a 50 ohm impedance on this bus.
All bus traces have the same number of vias (2) and are length matched to 38mm +/- 0.5mm. The clock line is on the longer side of this, but I wouldn't expect that to make this much of a difference.
Pullup resistors on the PCB are identical for the whole bus (47 kOhm to 3.3V).
I can't find anything in either datasheet that would indicate a variation in input capacitance on the clock line.
The rise time of the data line is within the realm of what I expected with the scope probe loading it down. I was looking at the bus edges because Microchip recommends trace impedances of 50, 68, or 75 ohms depending what piece of documentation you're reading.
The output driver strength of the ATWILC3000 is 13.5mA typical.
The default output current setting of the Pi CM3+ is 8mA. This is configurable (16mA max), but I'm not sure how to do it myself just yet. I think I found out how in the Linux Device Tree and I can't find anything other than the default 8mA in my current configuration.
I read through the driver source for the ATWILC3000 and couldn't find anything in there that would suggest that it has any control over GPIO drive strength (as expected).

Given the above, I'm wondering about the Pi drive strength. I know the Pi is sourcing that clock, but I don't know which direction the data lines are being driven in any given scope capture. If my good data rise times are coming from the wireless module, that would suggest the Pi is to blame.


texts: 50 Hz noise only in chest leads of 12 lead ECG

texts:
I am implementing a 12-lead ECG signal conditioning circuit. With the current design the bipolar leads (lead-I and II) are of sufficient quality with no visible 50 Hz noise. However, the unipolar leads (V1-V6) have large amplitudes of 50Hz noise. Each channel has an identical signal conditioning path. The circuit is powered from a GW Instek DC power supply. The first image is the output of Lead-II and the second the ouput of V5

What could be the source of this 50Hz noise in only the unipolar leads?

Edit: Circuit Schematic added