texts:
I'm on a quest to build a small cylinder (1/2" diameter) that illuminates for extended periods of time on a single charge. I've looked at numerous small sized batteries and decided on using 2 LR44s rated at ~170 mAh @ 1.5 V (each). This would be my first true engineering project so excuse my shoddy calculations.

I'm debating between using an LED OR an EL Wire design. From what I've read, an LED DC takes ~20 mA for ~7000 mCd luminosity (and ~10 mA for ~3500 using linear relation) which would give me about 34 hours (170 * 2 / 10) of continuous use.

Now from what I've read about EL Wire,

  each meter of high brightness EL draws about 10-15 mA at the high voltage

So if I have a 1" length keychain It would draw ~ 0.3 mA (0.025m * 12 mA) which would give me a runtime of ~1,133 hours (170 * 2 / 0.3). Is that at all accurate?

If it is, does an inverter of that size (1/2"x1/2") exist?


texts: Is a capacitor bad when it looks like this?

texts:
Hello I am new to the electronics field. I am looking inside of one of my synthesizers and I see some capacitors (I think they are Mylar, correct me if I'm wrong) that look like this. I know it is a bad sign if an electrolytic capacitor is bulging, but is it the same on these?

Is there anything wrong with these capacitors?

The issue I have is that the brass sound disappears over time after you turn the synth on. It starts with high volume but it slowly goes down in volume and sometimes it disappears completely.

The other problem is that there is bleed between the higher and the lower part of the keyboard. The keyboard is split in the middle. The sounds come from 5 different presets that you can turn up and down for the higher and the lower part of the keyboard. But if you turn for example the strings up in the higher it also plays a bit in the lower and vice versa.

I have studied the schematics and diagrams over the past week and only now did I discover that a significant amount of the electrolytic capacitors are not the same value as what it should be according to the schematic. But it is always a higher capacitance and higher voltage. But I don't know if the schematic is wrong or if there are wrong valued capacitors on the board.


texts: Step up 3.3V to 5V and draw 500mA without a voltage collapse/break down

texts:
I would like to step up 3.3V from my power supply with the help of a dc-dc-boost converter to 5V and then I want to draw 500mA by placing a 10 Ohm resistor between the output-pin of the boost-converter and ground.
The problem: The voltage drops down to 3.3V. (With 100 Ohm not)
Is there somewhere a module which can supply such a current draw? If yes, which one - sot-packages preffered?

I already tried those converters: MT3608, Pololu S7V8A and SX1308


texts: 8051 microcontroller problem to find execution time of part1 for a given code

texts:
For the below mentioned 8051 assembly code:
   Time elapse: MOV R0,#100
   Part 1  \$ \quad \, \, \,\,\$   : MOV R1,#50
   Part 2  \$ \quad \, \, \,\,\$   : MOV R2,#248
   Part 3    \$ \quad \, \, \,\,\$ : DJNZ R2,Part3
            \$ \quad \quad \quad \, \, \,\,\,\, \$  : DJNZ R1,Part2
           \$ \quad \quad \quad \, \, \,\,\, \, \$   : DJNZ R0,Part1
    Assumptions:
  1) Microcontroller is running at \$12 MHz \$ frequency and \$ 1 \$ Machine cycle is having \$ 12 \$ clock cycles
  2)MOV instruction takes \$ 1 \$ Machine cycle
  3)DJNZ instruction takes \$ 2 \$ machine cycle
    Calculate time required for execution of part1:
  a) \$ 2495600  \mu \$s  \$ \quad \$ b) \$ 2496300  \mu \$s  \$ \quad \$
  c) \$ 2495300  \mu \$s  \$ \quad \$ d) \$ 2496600  \mu \$s

My Approach:
Here \$ \# 100 \to \$ Decimal
$$\because \text{In 8051 : MOV Rn,#Data} \implies \text{#Data } \to 8 \text{bit}$$
We Know:
DJNZ Rn,addr:
$$\text{Decrement register 'Rn' and Jump to 'addr' if Rn} \ne (00)_H$$

Now,time required for execution of Part1:
 Part 1  \$ \quad \, \, \,\,\$   : MOV R1,#50
 Part 2  \$ \quad \, \, \,\,\$   : MOV R2,#248
 Part 3    \$ \quad \, \, \,\,\$ : DJNZ R2,Part3
          \$ \quad \quad \quad \, \, \,\,\,\, \$  : DJNZ R1,Part2
         \$ \quad \quad \quad \, \, \,\,\, \, \$   : DJNZ R0,Part1
So,time required for execution of Part1, \$ T = N * 12*T_{CLK}\$
where, \$ N= \$ total number of machine cycles  required for execution of Part1
$$\implies  T = N * 12* \frac{1}{f_{CLK}}$$
$$= N * 12* \frac{1}{12*10^6}$$
$$\therefore T=N \mu s \quad \dots (i)$$
For \$ N :\$
\$N= 1+1+\{ 247*2 + 1*2\} \quad \color{red}{[\because \text{leftmost } 1 \text{ is for 'MOV R1,#50' ;}}\$
\$ \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \color{red}{\text{2nd 1 is for 'MOV R2,#248' ;}} \$
\$ \quad  \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \color{red}{\text{ 247 times 'DJNZ R2,Part3' True Condition &}} \$
\$ \quad  \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \color{red}{\text{1 time 'DJNZ R2,Part3' False Condition}]} \$
\$ \quad \quad \quad + 49*2 +49 \{ 1 +248*2\} + 1*2 \quad \color{red}{[\because \text{49 times 'DJNZ R1,Part2 ' True Condition & }}\$
\$ \color{red}{1 \text{ time 'DJNZ R1,Part2 ' False Condition}]}\$
\$ \quad \quad \quad \quad \quad + \underbrace{98*2 +98 \{ 1 +1 +248*2 +49 (2 + 1 +248*2 )+1*2 \} }_{\color{blue}{\text{Calculation for 98 times}}} \$
\$ \quad \quad \quad \quad \quad \quad \quad + \color{green}{\{}1*2+ 1*1 \color{green}{\} \to \text{calculation for 99th time}}\$
\$ \quad \color{red}{[\because \text{'DJNZ R0,Part1' is True for 99 times} \implies \text{Part1 is executed 99 times}]}\$
$$\implies N= 2470348$$
$$\therefore T= 2470348 \mu s$$
,which is not there in the option, Key Provided:c)\$2495300  \mu \$s
so, please anyone help me to find my error...


texts: What happens in this current branch? In circuit analysis how to deal with branches like this?


texts: How to connect a microphone to apply audio signal to electronic circuit?

texts: I am working on a project where we have to design a band pass filter signals in audio frequency range. We have tested the filter design using Signal generator already, and now we want to see if it works with actual audio signal which has those frequencies in/out of it Passband. Is there any specific IC or something which can help me for this? We are using simple Active filter for filtering. Also, will it actually work as it was working with Signal Generator?


texts: How to determine the state of charge of a NiCD battery when charged via a Bench PSU?

texts:
I’ve a bunch of Sanyo Cadnica cells of various capacities in my possession. Though they are a bit old they have never been used and are NOS. I’m currently trying to charge a KR-FH 7000mAh cell. As per the label on the battery(please see picture below) it says at 700mA it should be charged 14-16 hrs and at 233mA for trickle charge.
I’ve two questions:

Currently the battery voltage is 0.89V since it sat in storage for like 5-7 years. So, I assume I can set the bench power supply to 700mA current and voltage to 1.45V. My power supply is CV type. But what if the battery was around let’s sat 1.09V or something like that where it’s not fully discharged? I’m aware a fully discharged elk is 1.0V usually.

Is the tricky stage mandatory at 233mA after completing the 14-16hr charge at 700mA?

I’ve never manually charged a NiCD or NiMH cell. Only Lead Acid batteries so far. Usually the NiCD and NiMH batteries I’ve used at the AAA, AA and C type cells that have either it’s own automatic chargers. I do not have a charger for the 7,10 &20Ah cells. So manual charging is my only option for time being until I find something.
I’m hoping to get some expert opinions from you guys.


texts: I found a TTL converter box made custom made many years ago. It says Namur_to_TTL converter on it. What is Namur? I googled but couldn't find a clear explanation.


texts: Finding simulator-specific range for user-defined physical type

texts:
I want to find out the maximum range for user-defined physical types like the following:

type resistance is range 0 to 1_000_000
units
  Ohm;
  kOhm = 1000 Ohm;
  MOhm = 1000 kOhm;
end units resistance;

(see also http://www.iis.ee.ethz.ch/~zimmi/download/vhdl93_syntax.html#pred172).

Documentation for physical types (VHDL LRM sections 3.1.3 and 3.1.2) says that the range is of integer type, so I could write range integer'low to integer'high which is the same as range -2_147_483_648 to 2_147_483_647. However, my simulator seems to use 64-bit arithmetic here, and range -40_000_000_000_000 to 40_000_000_000_000 also works, as does range -2**62 to 2**62 (while 2**63 does not).

Is there a canonical way to find out the simulator-supported range?
If not, how would I put the empirically-found 2**62 into a constant (for externalizing such simulator-specific code)? An integer constant won't cut it :)


texts: Driving a DC hobby motor using an AVR and a single power supply

texts:
I've recently begun experimenting with AVRs and am keen to progress beyond making blinkies to making things move.  I've tried to start with something easy, but it seems I'm already foiled!  What I'd like to know is this: is it possible to drive both an AVR and a motor from the same power source and without them interfering with one another?

The schematic below illustrates my initial attempt at doing this. The ATtiny is generating a ~3kHz PWM signal (1/3 duty cycle) on pin 5, with the intent of supplying a time-averaged voltage of 3V to the motor via the power transistor.  When I wire this up though, the motor just seems to cough and sputter.

Thanks heaps in advance,

Tim

p.s. I'm just wondering about the fundamental possibility/impossibility of what I'm trying to do: I don't expect anybody to debug my circuit for me! :-)


texts:
I have an assignment to create a counter that counts in the following way depending on input y

if y = 0 -> 0, 6, 3, 2, 1, 0...

if y = 1 -> 0, 5, 4, 7, 2, 1, 0...

Also it has another input x if x = 0 it counts up (for example 0,6,3,2,1,0) and if x = 1 it counts down (0,1,2,3,6,0).

I know that i can solve this by creating a big table with following columns

x|y|Q1|Q2|Q3||Q1+|Q2+|Q3+
----------------------------
0|0|0 |0 |0 || 1 | 1 |0
0|0|0 |0 |1 || 0 | 0 |0
0|0|0 |1 |0 || 0 | 0 |1
0|0|0 |1 |1 || 0 | 1 |0

...

But is there any simpler (and more elegant ) solution?

I can only use JK flip-flops. This is sequential logic so i don't have to worry about voltage or things like that... Also if it means something we use HADES for this


texts: Concerning truth table, Karnaugh map, cost and delay of a logic function

texts:
A logic function called \$defragment(n)\$ receives as its input \$n\$ bits, \$d[0],...,d[n-1]\$, and \$n\$ flags, \$v[0],...,v[n-1]\$, indicating whether the input is valid. The function returns only the bits which are valid, according to their order,\$\,y[0],...,y[n-1]\$. In case the number of valid bits, \$k\$, is smaller than \$n\$, the remaining \$y's\$ are assigned \$"don't \,care"\$. Attached is an example for defragment(4).
I was asked to first write the truth table for defragment(2), then its SOP, then try and evaluate its cost and delay based on its recursive expression which I'm expected to determine.
Are the Karanugh maps attached, and the SOPs, correct?


texts: Voltage shift 5V to 3.3V for PIC16LF145x 3.3V I/O input, several approaches

texts:
For USB device detection I need a way to shift that VBUS 5V to 3.3V in order being able to connect it as I/O input pin. The input pin should be high as long as VBUS = 5V, and low as soon as VBUS = 0V. This pin will be configured to generate an interrupt on input change. Only in high state USB functionality will be enabled as specified in USB 2.0 specification.

Low power consumption and low BOM is absolutely important in my case.

A design with a zener diode was rejected due the relative high required minimum zener current.

I decided to use a reistor divider with very high impedance.

simulate this circuit – Schematic created using CircuitLab

This voltage divider would ideally sink at most 0.4µA current as long as VBUS is 5V. The question is, is it enough for the PIC16LF145x micro controller I/O pin in order to detect a high signal? Theoretically it should since I/O pins are basically MOSFETS. Since there is some design specific capacitance it would take some time I/O pin to become "high", but this delay is no problem. However, there is also an input leakage current (datasheet, parameter no D060) of 5-120 nA. Does it mean, that the current provided into input has to be higher than that leakage current? Can R1, R2 even be higher for even lower constant sink current?

Is a MOSFET design the better approach?

simulate this circuit

An MOSFET for example this BSS138 also has some constant current in the range of some 100nA to 5µA (Zero Gate Voltage Drain Current, VGS>0V, VDS=0V). For this reason, this circuit is also not to be considered as an ideal solution.

What would you use, is there an even better/simpler solution (in regard to power consumption)?

Edit: Both the microcontroller as well as the USB host is powered by a battery (the same battery). However the micro controller should run independend of the VBUS voltage (USB host can be off, suspended...). My intention was to keep the energy consumption of the whole system as low as possible.


texts: What happens to a diode when it break-downs?

texts: What happens when you expose a diode beyond the break-down voltage, does it become conductive in both senses or non-conductive in both senses?


texts: how to represent a circuit when a simplified expression is just 1 or 0?

texts: For example if my boolean expression is defined by the function f(x,y)= x+xyz+yzx'+wx''+w'x+x'y+1. I know that A+1=1 no matter how A is. But if they ask me to represent the circuit with logic gates, what is the representation of it? I mean they generally ask me to simplify the expression in order to optimize the circuit. So how can I proceed?


texts: Does the wire gauge affect RF emissions when there is a relatively high current?

texts:
I'm reviewing wiring in an area that should have minimal RF emissions.
I was wondering if the AC current carrying wires were to experience high current if that could cause RF emissions of significance.  If so would increasing the thickness of the wire help to reduce emissions?
VLF radio is 3 - 30 kHz. AC has 50 and its harmonics, e.g. 100 200 Hz It's low frequency radio, I'd still regard it as RF.


texts: Bonding Electric Vehicles: Which System to Implement (safety)?

texts:
I am currently working on building an autonomous electrical vehicle and would like some input on which bonding system would be safest and most practical. The system battery is 48V (dc) and which feeds motors as well as runs through a series of isolated converters for lower voltage systems (24V, 12V). My understanding of the options as well as pros and cons are as follows:

Traditional Chassis Bonding
Pros: Simple, all enclosures/chassis at equipotential

Cons: If someone is touching the chassis and a positive node, you are the connection between hot and cold (with your heart in between).

Isolated DC System
Pro : First ground fault (i.e.; to chassis) will do nothing

Cons: 1) safe to touch until after first fault (imagine someone is standing on earth and touches chassis if first fault is to chassis) 2) fault protection will not trip til second fault.  3) Common mode currents across different enclosures could affect electronics after first ground fault
4) Detecting first ground fault (when it occurs and where)

Impedance Bonding
Pro: 1) If impedance selected properly perhaps the impedance of the resistor could reduce risk to personnel. 2) chassis and enclosures at same potential. 3) if impedance is selected properly circuit protection could still trip in ground fault condition.3) Monitoring the voltage over the impedance will allow me to detect if there is a ground fault that doesn't trip circuit breakers allowing me to electronically trip upstream (main) circuit breaker in this condition (via PLC).

Cons: 1) If impedance is not properly calculated either circuit protection may not trip properly (arc flash needs quick trip), or if too low personnel is no longer safe.

I am leaning towards impedance bonding. The low voltage systems are isolated so I don't think I could use them as bond return path (I don't know how isolated dc-dc converters would respond to an influx in ground current). Online people are generally recommending isolated system, however as this system's battery is at 48V DC (not HVDC battery) I think that the risk of an isolated system is low enough that this system would be the best option.

Please correct any misunderstandings, and any input/experiences would be greatly appreciated.


texts: Integrated Circuit design: Comparing the results given by corner analysis and Monte Carlo analysis

texts:
In IC design, corner analysis is performed to study the operation of the ICs under extreme conditions and Monte Carlo analysis is performed to ensure the mismatch is within the tolerance.
However, can the results given by the corner analysis and the Monte Carlo analysis be different? For exapmle, in a TT corner @27C, the output voltage is, say, 1.8V. But the mean output voltage given by the Monte Carlo analysis @ 27C is only 1.6V even if the corner analysis and the Monte Carlo analysis are based on the same set of design parameters (such as L and W).
Also if this happens, what would be the solution? Would different sets of parameters be used for the corner analysis and the Monte Carlo analysis?
Thanks


texts:
For my Super OSD Pro project (Super OSD is divided into two versions: Lite and Pro) I'm going to be using a 4-layer board. Are there any gotchas to be aware of when using 4 layer boards?

I was thinking of having the most widely used nets (+3.3V and GND) on layers 1 and 2, and having layers 3 and 4 for carrying signals. I could also occasionally use layers 1 and 2 for carrying signals where 3 and 4 are full up.

One other thing I'm also concerned about is how to connect pins to the right layers? Say I want to connect a pin on the top to layer 2. I've always routed a trace from the pin to a via, then dropped the via to that layer, but is there a better way? I've heard of via on pad but I've also heard that can produce bad results and is only really for BGA's, not the TQFP's I'll be working with.


texts: How to determine the variation in Q point given some resistor tolerances

texts:
In Microelectronics 4ed (Neamen), in page 157 Ex 3.8 they ask to find how Id and Vd would vary acording to some variation in the resistors. They don't explain how to do this in the book so i thought using partial derivatives on Id(R1,R2) with respect to R1 and R2 and see how the function behaves in the scope that they are asking me. Then evaluate Id acordingly. I couldn't arrive to the answer through this method because the derivatives weren't that friendly.
One could arrive to the answer graphing with matlab or using LTspice but i think there should be an easier way to do this. So that is my question, is there an easier way to arrive to the answer? How?

Ex 3.8: (a) Consider the circuit shown in Figure 3.33. The transistor parameters
are VT P = −0.40 V and Kp = 30μA/V2. Design the circuit such that
IDQ = 60μA and VSDQ = 2.5 V. (b) Determine the variation in Q-point values if
the VT P and Kp parameters vary by ±5 percent. (Ans. (a) RS = 19.77 k,
RD = 38.57 k; (b) 58.2 ≤ IDQ ≤ 61.08μA, 2.437 ≤ VSDQ ≤ 2.605 V


texts:
I am trying to build some DIY LED fixtures to light my saltwater aquarium. They need to be dimmable, and I want to dim them with Pots for convenience versus a controller.  It will probably be clear by the end of this thread that I am a novice at best, but here's what I have so far.

I selected the MeanWell LDD-1000h driver to run my lights. http://www.meanwell.com/search/LDD-H/LDD-H-spec.pdf

I chose this driver because it's PWM dimmable and in aquarium lighting, the spectral output of each diode is important so PWM is the obvious choice over CCR dimming. also, this driver is economical as I am building 5 fixtures (Multiple tanks) and there are very few drivers that have pwm dimming on board without exponentially driving up the price.
my plan was to build a controller using a 555 timer with the output pin connected to the dimming pin. According to the countless posts I have read through, this should work but in practice it has not.

I built this circuit among several others, but I thought this was going to do the trick.

I calculated the resistance and capacitance values using this formula: f=1/(.693 x C x (R1 + 2 x Pot1)) and where f= frequency in Hz, R1 and Pot1= Ohms, and C= Farads. knowing that I need a minimum of 100Hz, and a maximum of 1kHz, I plugged in the values of the Pot I am using, and various resistors and capacitors I have at my disposal until I arrived at these figures that while not perfect, should have worked.

I have scoured the net, built countless circuits and still cannot get this driver to dim. can anyone weigh in on this? I have seen some circuits built with mosfets connected between the timer output and the controlled device. I don't understand what that does and therefore am not sure if that might be the missing piece to my circuit? Any help would be much appreciated!


texts:
I'm designing a board that links sets of three Anderson PowerPole connectors to each other.

I traced the physical outline of the PowerPoles in the tDocu layer, but originally I did it incorrectly. I deleted the original wire in tDocu and drew a new one. In the package editor, it looks correect:

but in the layout editor, and when previewing the package from the layout editor, it has retained a portion of the original, incorrect rectangle (the thicker one):

Is this a common problem? Or am I doing something obviously wrong? I'm fairly new to EAGLE.

I have the library, board, and schematic files in a GitHub repo here.


texts: VISA: (Hex 0xBFFF0015) Timeout expired before operation completed

texts:
I'm writing a simple code in Python to remotely send commands from PC to RSHameg HM8134-3, using USB. I'm using visa to do so.

Something to note, when I write to it, it doesn't give me any errors(even though it doesn't change anything on the display as it suppose to)

rm = visa.ResourceManager()
scope = rm.open_resource('ASRL3::INSTR', write_termination='\n', read_termination='\n')
scope.clear()  # Clear instrument io buffers and status
idn_response = scope.query_ascii_values('*IDN?')  # Query the Identification string
print (idn_response)

And I'm getting this error:

Steps that I took so far to resolve the issue:
1. on the manual of the device, it's asking to have '\n' or \r\n in the end of the commands
2. I checked it on NIVISA and it gives me the same exact issue.
3. Tried to increase the timeout
4. Tried different bauds (300, 600, 1200, 2400, 4800, 9600, 19200).

Any other suggestions? I'm stuck!


texts: I should consider many specific values for a circuit's parameters and simulate the circuit in each case by PSpice to get output files. Because of high number of required simulation, I am searching a way to automate this process. Would you please help me?


texts: Is it Possible to Limit USB Port Current With a Resistor?

texts:
I'm working on a project that has a USB port connected to to a PIC32MX460F512L. The 5v for the USB is currently coming straight from the VREG. The port is only designed to accept USB flash drives, but it occurred to me that someone might decide to plug in a higher power device. I'm using a linear 5v regulator in my design, and it will definitely overheat if a device tries to draw say 2A from the USB port.

If something besides a flash drive is plugged into the port, I don't care if it charges, or functions. I just want to make sure neither the device nor my circuit will be damaged.

Here's some options I'm considering.

Use a dedicated protection IC. for example: AP21510FM-7

These look perfect, but I can't find any that will limit the current to less than 400ma. That's still too much for my reg so I would have to move to a switching regulator.

Use a simple resistor. Would that work?
Use a PTC with a load rating just above whatever flash drives typically draw.

This is kind of crude, but it should at least protect my VREG.

The most likely device that could be plugged in will be a cellphone I think. I know there are some standards for resistors on the datalines setting the current capacity. So will phones even try to charge from this port? All I currently have on my data lines is a TVS.


texts:
There is a question like,

Assume the voltage source connected across the series-connected capacitors as 50∠0 rms, 50Hz. The voltage source has a capacity of 100VA. Calculate the current passing through the capacitors.

For this, my solution is S = 100VA, and so the Irms = S/Vrms = 100/50 = 2A. Not sure whether I am in a right path? Could anyone please assist me with this? Thanks.


texts: Could anyone please be so kind and point me to a relevant lookup table please? I did some google searches but could not find anything. Thanks a lot.


texts:
I am learning on frequency control and voltage control. I am just starting the topic, so I am in little doubt.

Does voltage control has any relation with reactive power compensation?
How is frequency control associateed with power control?

If possible, could anyone please explain to me in simple words about voltage and frequency control.

Thanks in advance


texts: LED current source circuit design concerns

texts:
TL;DR: Read the bulleted list below.

I am designing a simple constant current source to power up some LEDs inside arcade buttons. My project consists of 20 of these buttons. Every button is internally composed by this circuit:

I can't change this circuit because it is locked inside the button's plastic body, so swapping the resistor/LEDs isn't a possibility. Also, I couldn't determine the LEDs specific part number; the manufacturer of the buttons didn't gave me any info about it's circuit. I believe they are 0805 white LED's with 2.8V Vf and 20mA If. And the resistors also seem to be in 0805 packaging.

So to drive them safely from 12V jack plugs with over voltage protection and some brightness control I designed the following circuit, using components I already have lying around:

The J1 and J2 are the connectors where I will wire up all buttons in parallel.
The V1 voltage source is placed there only for simulation purposes. So, now I make these questions:

Is this current source okay to drive my button's LEDs? Considering the 1/8W supposed limitation of the internal resistors.
Does this over voltage protection circuit works?

DATASHEETS:

http://www.ti.com/lit/ds/symlink/lm158-n.pdf
https://my.centralsemi.com/get_document.php?cmp=1&mergetype=pd&mergepath=pd&pdf_id=2n5060_series.PDF
https://www.infineon.com/dgdl/irfz44n.pdf?fileId=5546d462533600a40153563b3575220b


texts: Interfacing an RS422 driver and receiver

texts:
I am trying to interface an RS422 driver and a receiver.

What are the important voltage parameters I need to understand when selecting the relevant chips. From what I understand the most important is the differential voltage parameters.
Now, for eg -
I have a driver(RS422) that has a Differential output voltage of 1.8V(min) to 3.3V(max)(Vcc).

Now, I have a receiver of input differential voltage of -400mV to +400mV. Can I interface them 2. The Vcc of the receiver is 3.3V as well.


texts: Why is there no current flowing through the relay coil in this Qucs 0.0.19 simple dc circuit?

texts:
I just started looking at Qucs and am going through the components. I am puzzled by the results shown by the ammeters in the relay circuit below:

As you can see from the table, the circuit on the right is behaving as it would if the relay coil were energised, and showing 0.75 amps; but the circuit on the left is showing 0 for current, when it should obviously have a positive value there. I've tried swapping the coil terminals on the relay but the result is the same.


texts: What is the name of this wave shaped component?

texts:
What is the name and purpose of the following component?

It's a white rectangle with a S shaped thick trace on it.

Is it a resistor? It came from this teardown (microphone). Unfortunately, there is no information on it.


texts: Can someone explain this tube amplifier circuit for me?

texts:
I have a tube radio that has really low output (I mean the sound is barely audible at full volume). Probably some capacitor in the LF amp failed. However, after I downloaded the schematic diagram, I was intrigues and confused by the design of the output amp. While I can (most likely) repair the amplifier by testing the capacitors, I want to learn about electronics too. In this case, why it was designed as it was.

Here it is:

The left pentode is a 6ZH1P small signal pentode and the right pentode is the
Soviet equivalent of EL84.

Capacitor value explanation - if the number is integer (2200) then the units are picofarads, if the number has a comma (25,0), then the units are microfarads. Resistor values are in ohms, unless there is a "k" or "M" written or the number has a comma (which means that the units are megaohms).

I understand how a basic grounded cathode amplifier works, but this one has some weird (to me) parts, for example:

As I understand, C4-9 is for negative feedback, does it also behave as a cathode bypass cap? I mean, if I disconnected it, would the output increase or decrease?
Why are the screen grids of both tubes and the plate of 6ZH1P connected to a tap of the output transformer? Why is that tap used to provide power to the detector and IF transformer (and their tubes). It is connected trough a 20uF cap to ground, so audio feedback probably would not be there. Is the output transformer used as a choke?

EDIT: The actual fault was a leaky C4-7.


texts: Sampling data at 5MHz with 50Mhz clock in Verilog

texts:
I'm trying to make a controller for the MAX31855 thermocouple IC.
My FPGA works at 50MHz and this IC works at 5MHz, so I'm using a frequency divider to get the 5MHz clock signal.

Now the IC is sending to the FPGA their 32 data bits, at 1 bit per clock cycle. So I don't exactly how to sample this (5MHz) bit stream with a 50Mhz clock signal.

I'm also thinking in metastability problems.

Any idea?


texts:
In my design I have a constant problem with failing 24VDC fans. The fans are used all across the machine, however they fail in only one position, so I excluded faulty fan model as a source of problem.

The fault: fan does not start by its own means. When pushed with a finger it starts rotating, but slower than normal, and is very easy to stop.

The fan is powered from a stable 24V supply via a relay. Cables from a relay to a fan are approx. 1.5m long, and they share a path with some 230V cables. However, I measured 24V on a fan with a scope, and there are no spikes that could cause the damage.

I have run out of ideas, what causes the problem.


texts:
I have been given the problem

  "Using a block diagram for the RS flipflop, add appropriate gates for a D-flipflop".

Now, I can create the gate diagram for both RS flipflop and D flipflop (below), but I have never been tasked with creating a block diagram. I am a computer science student in a computer architecture class, so you can understand my confusion. I know SE likes questions that can have direct answers, so I'll stray away from asking "Where can I learn to create block diagrams". Instead I'll ask this:

How do I turn these gate diagrams into block diagrams?


texts: shielding noise cancelling headphones from mobile phone signal

texts:
I have 2 pairs of noise canceling headphones and both suffer from the same issue of picking up (and amplifying! very loudly) the interference from the GSM radio in my mobile phone. Yes its that buzz-clicking noise you get when you put a GSM mobile phone near a amplified speaker circuit.

And it's definitely the active noise-cancelling circuit causing the problem as turning off the headphones power switch immediately stops the interference noise.

My question is, are there any means to shield the headphones from the phones radio signal? For instance would clamping a balun around the lead to the headphones help?

The only thing I've been able to find searching online is this rather unhelpful forum thread.

UPDATE:
Thanks to the answer below giving the right keyword to search on (ferrite) I turned up a similar question, with an interesting point that if the phone is on 3G (WCDMA here in Australia) it should not cause the same noise problem and in fact anecdotally I am only experiencing the issue in poor-coverage areas where the phone is falling back to GSM instead of 3G service.

I'll still bug a ferrite core to clamp onto the lead to see if it helps in the case of a GSM signal.

As an aside, I think this would make for a nice little method for staff on airliners to check for people who have forgotten to put their phones in "flight mode".


texts: Is this correct for non-inverting op-amp?

texts: Do 0.1 uf and 100 k ohm act as low-pass filter in here?


texts: System Generator: How to know if my FPGA could have enough resources to perform a design

texts:
I am doing a design using System Generator, and I have some doubts if my design could be performed in a Virtex 4 FPGA.

Does anyone know what can I do to check this?


texts:
I have recently started playing with Arduino, as well as electronics in general.  This means I am a complete noob.  I needed some resistors for a project, so I ordered a variety pack.  I emptied the packs into a parts organizer.  I put the pack I ordered into separate drawers in order.  Once I did that, I started putting other resistors I had into the drawers.  This is where my question is.  I have a bunch of 220 ohm resistors.  Some came from the Arduino pack, and some from the pack I ordered.  I have a number of 200 ohm resistors, from somewhere I dont remember.

Is there a big enough difference to separate the 200 ohm from the 220?  Or are they "close enough" that it doesnt matter?  Does this apply to every resistor that is "close"?  Another example is I have 2k and 2.2k resitors.


texts: Arduino - reading translated voltage gain from transimpedance amplifier

texts:
I implemented this circuit with a feedback resistance of 330 kilo ohms and a photodiode, which detects wavelengths in the infrared range.
I used the LM358 to amplify the photocurrent into voltage gain. I am using an Arduino board to read the voltage. I simply read the analog signal at the output of the amplifier.
The Arduino does not give a proper reading however. I am specutlating, that the problem is either with properly connecting to a common ground, or a damage to the amplifier.
I used a different circuit before, and it gave a reasonable sensitivity to multiple degrees of intensity. The problem however was the range of the photodiode. It is supposed to be from 0 to 1024, since the ADC in the Arduino is 10 bits. With this circuit however,it provided a range from 0 to 340 only.
So in summary with this shown circuit, how do I read a maximized range of measurement from 0 to 1024 properly?
Datasheet of the amplifier.
Datasheet of the photodiode.


texts:
I have a question regarding the ESP8266-01.

Do I need to solder a wire from GPIO16 to reset if I am using a button to wake the ESP module from deep-sleep mode ? Or is it needed only if the module must wake up by itself?


texts: Using superposition to solve circuit with one voltage source and a dependent source

texts:
If i use super position to solve a circuit with one voltage source and one current dependent voltage source, does it make sense to use superposition to eliminate the independent voltage source, and do mesh analysis, and then turn on the independent voltage source and do mesh analysis again, and add the results of the two?

Or should i also turn off the dependent voltage source when i turn on the independent source to do the analysis?


texts:
I'm having a hard time understanding Chassis Grounding. From my understanding, the frame of a plane is used for that and all of it can return to the batterie.

Given my understanding, it remains a closed circuit that always has the same number of coulomb (Batteries and Chassis included).

Let's pretend a lightning hit the plane now. Wouldn't that add coulomb to the closed circuit? If so, is there a limit of coulomb we can add to the frame? Are we recharging the battery?

Then, isn't that new amount of charge in excess to the batterie circuit capacity? Is it why we sometime get a static shock when getting off our car?

It seems like a lot of question, but those questions all explore one aspect: what happens to closed circuit charge once the lightning hit to the moment the charge returns to normal? It could also be charge accumulated from air friction, I'm curious to what happens to the new charge added to the circuit since I'm used to closed circuit.

Thanks in advance


texts: Why do we connect a resistor before a Zener diode?

texts:
Why do we need a resistor in a Zener diode circuit, like in the diagram below?

I understand it is to limit the current but how so, and why do we need it for a Zener diode?

Does selecting different values of resistors affect the circuit performance? So when we are selecting a Zener diode we look in the specifications at different reverse currents that can flow through them. But if those can be changed through resistors, can we select any Zener diaode at a voltage, without looking at the maximum current?


texts:
I have to design a bio potential measurement system:

AD converter and the connecting digital / software part
an analog amplifier stage: basically a regular ECG amplifier composed
of discrete instrumentation amplifier

Googling around I see that the instrumentation amplifier's reference input is driven by a miller integrator feedback.

My question is:
what is the purpose / advantage of this miller integrator feedback?

I think, remove DC component can be easy in software side, hardware cost, size, complexity and PCB design can increase dramatically.


texts:
Regularly I buy ICs from China so I know there can be differences in shipping.
Mostly ICs are sent in either plastic IC storage tubes, and mostly stuck on foam. However, today I got them without any protection like this. I got one extra, but as can be seen at least 3 are quite badly bent. Although it seems bad, after straightening them with some pliers I could easily put them in a breadboard and after removing them from the breadboard they look more or less straight.

I am just wondering about the implications of bending (the only thing I can think of is because they have been bent, they might break when the legs are bent again I will prevent of course), but maybe I can get in trouble:

When soldering them?
Less conductivity?
Heating problems?
Anything else?


texts:
I have a circuit (Death of Zen audio amp) , which requires 2 12 volt zener diodes.
What is a safe wattage rating for them? Does this work?


texts: why are pm (permanent magnet) machines synchronous? and how do I start them?

texts:
Let's consider just one pole pair.

I know from reading my book that a pm machine will have the angular speed of its rotor equal to the speed of the rotating magnet field that the three phase winding creates.

If this was not the case then the (average?) torque would be zero.

I did some research, and it seems that this behavior is due to the fact that two magnetic fields try to align, with a torque that's proportional to the product between their magnitudes and the sin of the angle between them.

Given that I have NO idea what that law is (its name, where does it come from...to be honest it seems an elementary explanation about how two magnets attract each other), I wonder if this is the case. does the motor torque come from this phenomenon? What would be zero (if anything, later on the book it states that if the speed are different I just wouldn't get a constant torque), the ''average'' (on what? a period?) torque, or the instantaneous? I'd say it's the average over a period of the sin that appears in that formula, but it's very tricky to reconstruct it to the time domain.

I also read that a pm machine will either run at the excitation field speed or not run at all. No idea why is that, tho. and if this was the case, how would I start them? as soon as I give them a rotating field, since they are not moving they have different velocities... then the torque would be zero (from the book)?
It doesn't make sense.

And what if, by any chance, when I start the machine the two fields are aligned? Would I get the minimum possible torque (around 0) or something else would happen?


texts:
I have a DC motor that uses 9.6 volt batteries. Can I use 3 of my 3.7 volt lithium-ion polymer batteries (11.1 V) to power this motor?

Somebody please help me. I have tried 2 of the LiPo (7.4v) and it could not give me the expected result. I am currently scared of burning my DC motor. I do not have access to 9.6v batteries.

Also if there would be a possible circuit that can step down the voltage please do help me with it. Thanks a lot.


texts: In demonstration of jumping ring if we assume dc source connected to solenoid, according to most of books, when we place a metallic ring over the solenoid and as soon as we turned on current, due to change in flux an opposite current induces in ring and causes a very high repulsion and ring flies off, but my problem is that generally almost everywhere they consider ring of aluminium or copper and derive a rigorous mathematical model of it but what happen if instead of copper or aluminium we take a ring of ferromagnetic material (steel)? In that case what will be behaviour of ring i.e attraction (because ferromagnetic material attracted towards solenoid due to magnetic field gradient) or repulsion due to lenz law? And can we derive rigorous mathematical model in that case?


texts: How to make a continuous current from a flashing source?

texts: I have a machine running, when a problem occurs, it stops and sends a 12VDC light bulb flashing every second or so, how can I get a constant signal from it to use this signal in the VFD to perform a short time deceleration, I want to do this to differentiate between a normal stop and an emergency stop.


texts: What other components do I need to add to make this circuit send values to analog pin on Arduino ?


texts: Why does a MOSFET have 2 semiconductor leads?

texts:
I have a question on the mosfet construction. Considering a n-channel enhancement type mosfet, it has two n-type regions connected to source and drain terminals. Also there is a p-type substrate. If source is connected -ve and drain is connected +ve voltage, there is no current flow unless there is a positive voltage in the gate which attracts some electrons to form the n-channel and hence conduction occurs.
It seems the same effect could be achieved using only one n type region connected to drain and no n-type region connected to source in the mosfet. alternate mosfet implementation

There would be an depletion region with p-n reverse biased (drain +ve and source -ve). Gate being in a positive voltage can create a n-channel and let current flow. The device could operate in pinch-off or linear or saturation region.
I was getting the feeling the source side n-region is redundant. Would like to know if it serves a purpose?


texts: Two SR latch implementations and De Morgan's rule

texts:
Here, I modify the encapsulated area of an SR latch(with NOR gates). The encapsulated area on the first circuit(with the NORs) is equal(at least, I think so) to the wider encapsulated area in the below circuit. So, I think that my inputs can be and should be used in the same order without changing it.

The BLUE ENCAPSULATED area represents the same SR latch again, but with R' and S' are used as input names and those NOT gates are eliminated. Eveything seems fine till here, however, at everywhere else, I see SR latch created with NAND gates as follows:

The difference of these with my drawing is the ordering(up to bottom) of S' and R'. And unfortunately, this one is the one which is correct and mine is wrong.

So, where do I do a mistake? Is there a conceptual misunderstanding in my thoughts?


texts:
Tried to model an equivalent circuit for a 3-phase TN-S system to model inrush behaveour. Was working for a while, and now nothing beyond the "Power Cable".
Probably an obvious reason, but unable to find it.. appreciate any help.


texts: How to calculate the heat dissipated by a battery pack?

texts:
I have a battery pack consisting of 720 cells. I want to calculate the heat generated by it. The current of the pack is 345Ah and the pack voltage is 44.4Volts. Each cell has a voltage of 3.7V and current of 5.75Ah.

The pack provides power to a motor which in turn drives the wheels of an EV. I wanted to design the cooling system for the battery pack, so wanted to know the heat generated by the battery pack.


texts: Generate current and power LEDS off a bike wheel

texts: I have a bike that I am planning to attach LEDS to the wheels and make them light up when the bike is moving.  To do this I was planning on trying to use the moving wheels to generate current for the LEDS.  How would I go about generating current off the wheels spinning?  Also, will I have to put a voltage regulator on the device to make sure it doesn't generate too much current?  If so do I need a battery or somewhere for the current to go if it can't be used by the LEDS?


texts: How to eliminate 50 Hz noise from amplifier's output

texts:
My goal is to amplify signals with a frequency from 100Hz above. My circuit is looking as the picture below. With an oscilloscope, I am trying to measure the output of the amplifier.
If the input of the circuit is not connected at all, I can see a small 50Hz signal. Touching the input gives me a huge 50Hz signal which comes from the AC power supply from around the room. But I expected them to be eliminated due to the capacitor added.

I know that the oscillator's probe behaves like an antenna. Maybe it induces the noise into the feedback of the amplifier? But then, I don't understand why touching the input increases this noise.


texts:
My son is trying to solve contest tasks in physics. Among the questions, I found the following one

Let me translate.

Find measurements of current meters within the circuit, shown on the picture. Resistance of current meters to be considered as much lower than resistance of the resistors.

Power source is 12 V, resistors from left to right: 1 Ohm, 2 Ohm, 2 Ohm.

I have some knowledge about electronics and circuit design, but this task astonished me. In my option:

it is not correct to connect current meters this way, and current meters are having extremely low resistance, at the same time this their resistance is defined;
if I would consider this circuit, as any stupid circuit can be built by the human, saying that "consider resistance of current meters to be much lower that resistance of resistors" does not help, and to calculate circuit current meters' resistances are required.

Do I miss anything?

Edit: following conversation and answers I redrawn the circuit - here it is


texts: Multiple Vibration sensors via single optocoupler

texts:
I am designing simple security system to protect 20-30 windows (total length about 50m) with vibration sensors (based on SW-420 modules). Window are on the roof and due to environment i use optocouplers for controller isolation.
I want all of that sensors to be connected to one wire, something like Logic OR.

Explanation:
When sensors has LOW on OUT pin, optocoupler cathode has ground pulled via R21 resistor - controler pin has LOW.
When sensor is active, transistor Q sends 5v to optocoupler cathode, and IO pin getting HIGH via Pullup resistor R20.
Note: I places pulldown resistor at the end of line. So if signal or ground wire
is terminated (cutted, disconnected), alarm will be activated.
I tested this circuit with only two sensors (don't have any more).
Look's like working well. But i am worrying about stability and safeness when there will be 20-30 sensors on single line 50m long.
Also i were trying to replace sensors with HC-SR501 PIR Motion.
Unfortunately this circuit not working. Looks like 3.3v with 0.6v drop cannot drive 2N2222. May be other transistor will work?
So, will this circuit works stable and safely when scaled up? (may be some capacitors).
Also is R23/R24 resistor is necessary (i tried without them, and placed in schematic just in case).
Is 2n2222 is right choice for this circuit?
UPDATE
Another idea is  breaking connection between led cathode and ground with mosfet

Will this works?
Is 2kOhm for mosfet gate pullup is enough/to much?
Will mosfet close when transistor closes?


texts: Transmission lines/Antennas power delivered to a load, why halved?

texts:
When seeing transmission lines and antennas in class we saw that the power delivered to a load is equal to:
$$
P = \frac{1}{2}\cdot \left | I \right |^{2}\cdot Re\left \{ Z \right \}
$$
 Where I is the current input of the load/antenna and Z is the impedance of the load/antenna.

What I don't understand is, where does this division by 2 come from? In other classes we've learned that P = VI = I²R but this seems to be different?

I tried to look for an answer to this online/in books but I couldn't find one. All the resources I found just threw that formula out there without an explanation of where it comes from.


texts:
Given a need for a single 2G × 32 bit DDR3 memory block, which configuration would be ideal and why? What are the pros and cons of each approach?
A: Two 2G × 16 bit memory ICs
or
B: Two 1G × 32 bit memory ICs
I think that A is better than B because the address/bank/control lines can be shared among both ICs which reduces the needed memory controllers. This however, might create timing skew problems between both ICs.
How would I scale this if I wanted to create a 16G × 32 bit DDR3 DIMM for example?


texts:
It amazed me recently to have found 3 tiny Sot-232 transistors inside a 12V led controller. It can't be serious, but after digging and testing it with my 10 watts power LED mounted on a CPU heatsink for 30 minutes, the huge heatsink was hot to touch, yet when stupidly touching the tiny SOT-232 transistor, it was not even warm. It's a AO3400 N-Channel MOSFET; According to the datasheet, it's Max Vds is 30V, and Id is 5.8A.

Question 1, so technically is this tiny transistor capable of switching up to 30V * 5.8A = 174 watts?

Question 2, but according to the datasheet, it can only dissipate 1.4 watt. What is the difference between Power Dissipation VS Switching Power?

Question 3, Again, according to the datasheet, we only get 5.8A when VGS=10V; but since I am planning to use this with a MCU which has a HIGH voltage level of either 3.3v or 5v, what is the approximately expected switching current? and how it's calculated?


texts:
I have a large transformer and I just can't figure out its pinout.
I simply want to make a high voltage circuit but can't find the proper coils.
One side has 2 wires whose resistance is 0.8 ohms and the other side has 13 wires. Some of those have resistances of about 0.4 ohms. I don't think that is normal.
What am I doing wrong?
I am planning to plug this into a ZVS circuit and see if I can make some arcs.
My transformer: TKP0278-E142Z
Here is my transformer on eBay: https://www.ebay.com/itm/SONY-STR-DE997-Replacement-Repair-KGCOMP-Power-Supply-1-443-265-11-TKP0278-E142Z-/113208976789


texts: Why does voltage drop in a simple zener diode based voltage regulator?

texts:
This diagram is from https://www.homemade-circuits.com/simple-voltage-regulator-circuits-using-transistor-and-zener-diode/

The article says that when the input voltage exceeds the zener diode's rating, current will pass through the zener diode and that this will somehow cause the input voltage to drop and therefore cause the output voltage to do the same.
Why does the voltage drop? There is a current limiting resistor stopping the input source from being overburdened, and if there wasn't, that would be a short circuit.
Also, how does this circuit relate to a chopper circuit?


texts: Addition of limit switch for power supply stops circuit from working. Circuit works fine without the switch?

texts:
I am having an issue with a limit switch to turn on and off a circuit. I am using a L7805 5V regulator with a regular 9V battery as the power supply for my circuit. When I plug in the 9V battery normally, the circuit functions fine, however, if I add a limit switch/microswitch to turn on and off the circuit, the circuit does not function. I've tested countless things to no avail:

Different limit switches with different current ratings ranging from 2A to 5A and 50V to 250V AC or DC
Confirmed that the limit switches work properly when pressed using the multimeter's the continuity function
Made sure that the circuit works fine when I plug in the 9V normally by hand into the 5V regulators
Switched the breadboards that the circuit is currently onto different breadboards
Edit: Forgot to include that I've tried putting the limit switch in different places, I tried putting it between the 5V regulator and the 9V battery directly, and the 9V battery's ground and the 5V regulator's ground. Both do not seem to work either

I'm very confused at this point because the limit switches seem to function fine, and the circuit also functions fine without the limit switch. I did a search already and didn't find something similar to my issue, so apologies if this has already been asked. Any possible ideas/or even remote pointers would be much appreciated because I'm still new to electronics. A schematic of my circuit is also attached below in case it helps, its purpose is to drive a servo for a specific amount of time. Much thanks!


texts: Use SCR dimming info to feed 1-10VDC line

texts:
Hello I am modifying an electronic lighting fixture to use LED instead. I have everything I need already, 80W LED, Power Supply, etc. There are just two issues I cannot resolve.

The original fixture uses SCR dimming chip (controlled by electronics/computer) to power and dim a 24VAC Halogen Bulb at 250 Watts. The LED Driver accepts a DC Voltage between 1-12VDC. Im trying to somehow get that dimming information from the SCR, inputs, or outputs and convert it to 1-12VDC depending on the dimming amount fed into the SCR.

The second issue may be easier.. Since im powering the LED seperately, it needs to know when to turn on and off. I figure some type of circuit which can detect ANY voltage from the 24V halogen bulb leads  to and trigger the LED power supply to turn on. I know relays do this but from my understanding relays need a constant control voltage.

The schematic for the dimmer circuit is here (Page 14 labeled dimmer).. I do see +5V and "MOC_EN" not sure what that means or if it can be used
https://www.highend.com/pub/products/automated_luminaires/Trackspot/Schematic/Tspotr15.pdf


texts: What proximity detection technologies can work through glass?

texts:
I'm looking for sensor options for proximity detection through a pane of glass. Something that will sit 6-24" on one side of a pane of glass, and be able to detect presence the same (roughly) distance on the other? I assume ultrasound won't work, but am not sure about infrared. If not, are there other options?

Edit per this link from the comments, most glass is opaque to IR, so no, it won't work. That leaves the second part of the question - are there ways to detect presence / motion on the other side of a pane of glass. Video-based motion detection won't work because I need to be able to restrict distance (i.e. something present/moving within a fairly tight distance of the glass). Use case is something along the lines of a home security motion sensor looking out the window.


texts: Are there any conventions that allow one to tell which electrode is source and which one is drain?


texts:
I am considering using either a trimmer capacitor or inductor combination with the other fixed valued component to create LC tuned filter for 1MHz.

I want the system's resonant frequency to remain stable over the temperature and time.

What parameters should I look for?

Also, looking at the datasheet below,
Coilcraft Variable Inductor Datashseet

It states LMin, Lnom, and Lmax.

Do the three parameters above man the value of the inductor when it is at it's full inductance(when it's completely turned?)?, Or as I turn, the inductance moves from only LMin to LMax?

1180 nH rated inductor's LMin is 1010nH and LMax is 1340nH. Does that mean that one end of the turn is 1010nH and the other end of the turn is 1340nH? or does that mean the range of inductance at maximum turn?


texts: Creepage distance for PCBs handling line voltage AC?

texts:
What is the required creepage (e.g. trace-to-trace) distance for PCBs handling 240VAC rms? What about 120VAC?

This is for UL and CE certification.

The standards for PCB Creepage (e.g. the distance across the surface of a PCB between high-voltage connections) are locked up in proprietary, pay-only IEC standards (specifically, IEC Report 664/664A ).

This is troubling, as following these standards is a good way to ensure safety, even if you never intend to actually get your project UL or CE certified.

Can we get a nice summary of what trace-trace spacing should be maintained for common voltages (e.g. 120V, 240V), with common materials (e.g. FR4, etc...)?


texts:
I'm designing an application for this mangetic angular sensor
https://www.monolithicpower.com/Portals/0/Documents/Position%20Sensors/datasheet_MA700_rev1.2.pdf
Because this is precise and sensitive piece, I'm thinking if I should have additional VCC filtering.
Any thoughts welcome!

This sensor IC will sit on a tiny PCB, which will be connected to main controller board with SPI flat cable.
Should I place capacitor on the main board just before the cable?
Should I place capacitor on the tiny PCB?
Should I have inductor in addition to capacitor?
Should I not worry about it at all?


texts:
Greetings guys and gals,

I am seeing some odd behavior in my PIC-controlled circuit and need some help from the experts.  I have a PIC18 at 3.3V turning on a bathroom vent fan via a relay.

The fan is the following model:

Panasonic FV-30VQ3
Current rating of the fan is 610mA @ 120VAC.

Schematic of my power/control attached.

U1:  AC/DC converter VSK-S5-5UA (please excuse part number in schematic is obsolete)

U2:  MMBT2222A to turn on the coil

REL1: PCN-D3M (TE Connectivity:  120VAC/3A, 25mA coil current)

R1: Connects PIC board GND to wall GND, but is not populated currently

The MKDSN's are 2-position terminal blocks:

X1: Input power from the power cord

X2: Connects fan and input GND

X3: Output power to fan

X4-1: Sends +5VDC to PIC board (other PIC board converts to +3.3VDC with linear regulator w/100uF ceramic cap at output)

X4-2: 3.3V logic from PIC that turns on relay

With no fan attached to X3 and the PIC cycling the relay on and off, the +5VDC, and subsequently 3.3VDC on the PIC board are stable.  All is good here... no voltage drop, transient, or current flyback.

When I connect the fan to X3, I see the behavior that is shown in the attached screenshots of my oscilloscope.   This is the +5VDC:

Clearly the guts of the fan are to blame for the issue, but I would not think that the transients that I am seeing could exist with the amount of capacitance on the +5VDC node (C1 and C3).

The schematic provided on the sticker of the fan shows a capacitor on the white (line) of the fan itself.

Any ideas where this is coming from and how I can suppress this?  The transient is causing my PIC to brown out and behave erratically, as one would expect when your operating voltage fluctuates so much.

Do I need more capacitance?  Capacitor on the 120V of the fan?  I mostly work with low power/voltage microcontrollers and FPGA's so 120V is not in my wheelhouse.

Any thoughts or input is appreciated.  Thanks in advance, much appreciated.


texts:
You get your PCB back from the manufacturer. It is a new design, you have of course bread-boarded all the major parts, but you know there are going to be problems. There are just too many things that can cause problems, e.g.:

Errors in the schematic
Errors in the layout, not found by the ERC/DRC
Misplaced parts during soldering
Shorts and the like during soldering
any combination of the above

I've had two relatively complex boards lately where I've basically had to de-populate the entire boards after assembly in order to locate the error. I found the errors, but the boards were scrap.

I've tried to start with the bare minimum of parts and the parts that can't be hand-soldered (I'm using paste, stencil and toaster). Typically this would be the MCU, the JTAG connector and a few capacitors. Then I'm gradually populating other areas while checking them for problems.

This approach works, but is really slow. I also have to comment out/comment in any code that assumes the presence of some particular hardware.

Does anyone have tips/suggestions on how to approach newly designed PCBs?

EDIT: I'm mainly thinking about the kind of problems that leaves your board dead, like hidden power rail shorts, or anything that bricks the MCU.


texts: Applying hybrid-pi model of an npn-BJT to a pnp BJT in small signal analysis

texts:
When doing the small signal analysis of a circuit containing a pnp BJT connected to either the emitter or collector (or base?) of a npn BJT, is it possible to apply the hybrid-pi model for the npn-BJT and apply a minus sign to the current as in -gmVbe  since current flows opposite?

simulate this circuit – Schematic created using CircuitLab


texts: Buck regulator to match an analog voltage

texts:
In desktop computers, it's common to have headers that control fans with a 0-12V analog output, capable of up to 1A. This works fine for one or two fans, but with more than three fans, you can exceed the 1A rated current.

The obvious solution to me is to make a voltage buffer with power fed from the power supply's 12V rail, and I'm amazed this isn't available already. I know how to do this with an op-amp, but that would not supply enough power and it seems that a buck regulator would be better suited to this, but I can't figure out how to do it. Are there any buck regulator ICs that would be able to implement a 0-12V 5A voltage buffer, fed by a 12V input? Is there a better way to do this? I don't care about high frequency response, and a ~10Hz lowpass filter would be ideal.


texts: Observing ethernet auto-negotiation packets using oscilloscope

texts:
In an answer to one of my previous posts seen here: Verifying 802.3 auto negotiation, @Zac67 mentions that by using an oscilloscope I could observe normal and fast link pulses that are sent in order to determine ethernet data rates of newly connected ethernet devices. How could this be done?

I have a basic understanding of oscilloscope functions. Would a logic analyzer work as well? Thanks for your help.


texts: am I on the right path to fabricating a pcb for my robot

texts:
So I'm a software engineer with the dream of wanting to build some cool robots and understand electronics as a result.

I'm currently hacking with a raspberry-pi and arduino, but mostly I'm trying to play and experiment a lot with a variety of things, just to know what pitfalls etc I will run into.

My arduino and and pi are friends over serial-usb now and I cooked a second robot with an Arduino Uno R3, it can receive commands on serial. This is what it looks like (one 9v powers the arduino, the AA holders power the motors):

So wandering around I found out about fritzing and http://oshpark.com. I designed my board in fritzing :

I exported to the gerber files and uploaded it to http://oshpark.com, it's a pretty decent price so far!

My questions:

I'm a complete noob here and did this with google-fu. Is this how it is normally done? Any obvious mistakes or thing's I've missed out here?
I looked at the PCB layout recommendations post and there isn't a mention of fritzing, and eagle costs a $1000. Am I missing anything great without it. (For a moderately to complex robot board I plan to make)
I assume once this printed, it's just a flat board right? And then I will solder female headers and IC holders to connect other parts right?
Do I need a one-layer or two layer board? (What different would each one make?)


texts: Does a 300W Transformer use 300W when a 12W appliance is connected?

texts:
I've been wondering: if you connect a 12W device to a 300W step-up transformer, how much power is consumed?  Does it use the whole 300W the entire time, regardless of what's connected, or is it an upper-bound?

I'm also keen to learn why.


texts: I'm starting to use Altium Designer. Can't find how to export drawings to picture (JPEG,GIF) format. I do File->Export I found mystic menu Add Exporter that gives me nothing. I'm not sure I'm on correct way. How to export pictures in Altium Designer?


texts: How do manufacturers rate the voltage of light bulb or any types of load?

texts: How manufacturer make light bulb or switch for a  specific voltage? How it is determined that the light bulb will work at the maximum specific voltage?


texts: Temperature compensation in transistor current cource

texts: I am working with analysis of BJT current source. I didn't get the explanation of temperature compensation in NPN transistor with PNP and pull up resistor. How does it work actually?


texts: How much energy can the iphone output into an external device?

texts:
I am having a lot of trouble finding any concrete information online about how much voltage/amperes the iphone 30pin as well as the new 8pin connector is capable of outputing to an external device.

Does anyone know if, and if so how much, power the iphone is capable of outputting?

Would appreciate any links or resources that may help discuss this.


texts:
I plan to put a metal cover to the bare toroid transformer, but the sides would be almost touching (I couldn't find other chassis around). I'm aware the bolt at middle musn't be connected (or shorted to top case) to avoid shorted turn. But with sides almost touching metal chasses, how much current would be inducted or lost to the metal cover?

This is the spec of the toroid transformer. Generally, what must be the clearance in the sides for the metal case, and what negative effects if its' touching?


texts: Should I spread the pads out on the footprint of a THT LED?

texts:
I have a 4 pin RGB LED with a common anode.  I'm trying to make my first PCB and I am creating the footprint for the LED now.

I don't have a datasheet for the LEDs unfortunately.

I have a ruler DigiKey sent me and it seems like the pins fit snugly in the 0.6mm hole.  I think the space between the pins is roughly the same as the pin width.

I think that gives me a pitch of 1.2mm.  I was considering a 1.0mm pad with a 0.6mm hole.  That'd give me only 0.4mm around the pin for soldering and paltry 0.2mm between the pads.  This seems like a lot of extra work for the small benefit of being able to settle the LED all the way down on the board and solder the pins on the back of the holes.

Another option I considered is spreading the pads out using roughly the entire 10mm of space under the LED.  With a 0.1mil pitch, the LED would stick out further from the board but soldering would be somewhat easier because I could have larger annular rings.

Should I spread the pads out on my THT LED and how do you go about making decisions like that?


texts: A question about 16 bit ADC representation

texts:
For a 16 bit ADC with a -10V to +10V analog input range I have read the following:

The resolution \$ \text{delta} = \dfrac{20V}{2^{16}} \$

16 bit 0000000000000000 corresponds to decimal 0 and this means the voltage read by the ADC is between -10V to -9 999.695V.

Similarly 16 bit 1111111111111111 corresponds to decimal 65535 and this means the voltage read by the ADC is between +9 999.695V to +10 000.

But I have couple of questions here where I get confused:

1-) If the ADC samples a voltage of +9 999V, will it register as 65535 or 65534?

2-) How about 32767 and 32768? Do they both represent OV? It seems to me 32767 is registered if the voltage is between -20/2^16V and 0V; and 32768 is registered if the voltage is between +20/2^16V and 0V. Is that correct. If so it means for 0V there are two steps unlike other voltage readings.

3-) Is the resolution \$ \dfrac{20V}{2^{16}} \$  or \$ \dfrac{20V}{2^{16}-1} \$?

EDIT:

I plotted in Python quantization of a sinusoid for a 3 bit ADC.

Which plot below represents better a 3-bit ADC converter quantizing a 10V 1Hz sinusoid input in this case sampled at 512Hz rate:

3 is the number of bits.

Below call it Plot 1, the number of levels are odd i.e (2^3)-1:

And below call it Plot 2, the number of levels are even i.e 2^3:

Which one above represents an ADC quantization better?

EDIT 2:

In response to Dirceu Rodrigues Jr and the transfer function he provided in his answer, I tried to plot it in Python (3 bit ADC for -10 to +10V input versus binary code in decimal):

import numpy as np
import matplotlib.pyplot as plt

#ANALOG SIGNAL:
va = np.linspace(-10, 10, 10000 ) #Analog input from -10V to +10V
fs_p = 10.0
fs_n = -10.0

#DIGITAL OUTPUT CODE:

n=3 #ADC resolution

vd = ((va - fs_n) / (fs_p - fs_n)) * (2**n) #Transfer function
vd = (vd).astype(int) #output code

plt.plot(va, vd,'.b')
plt.plot(va, vd,'-g')
plt.xlabel('Va (Analog input)')
plt.ylabel('Vd (Output code)')
plt.show()
plt.grid()

Here is the output:


texts: What difference does it make to an appliance whether the supply is sinusoidal, or any other shape?

texts:
Just what the title states.

I understand some appliance/s may be damaged if the supply is any shape other than sinusoidal. E.g. sawtooth, square ...

Why is this the case? How does the shape of the supply signal matter to an appliance?


texts: What resides in the different memory types of a microcontroller?

texts:
There are different memory segments to which various types of data are put into from C code after compilation. I.e: .text, .data, .bss, stack and heap. I just want to know where each of these segments would reside in a microcontroller memory. That is, which data goes into what type of memory, given the memory types are RAM, NVRAM, ROM, EEPROM, FLASH etc.

I have found answers to similar questions here, but they failed to explain what would be the contents of each of the different memory types.

Any sort of help is highly appreciated. Thanks in advance!


texts: Is it possible to use an H-bridge IC as dual MOSFET driver?

texts:
I've been looking for cheap and easy ways to drive a MOSFET with PWM and I came across a simple 555-based driver.
But that gave me an idea, since push-pull setup is used for driving MOSFETs, and an H bridge is basically a double push-pull, is it possible to use an H bridge motor driver IC, namely the l9110, to drive two MOSFETs?
The l9110 is intended to drive one motor, but I think I can connect each output to a MOSFET gate and drive 2 MOSFETs with it.
Here is the datasheet of l9110.
Another datasheet. It's in Chinese but has an internal diagram too.
Notes:

I couldn't find a maximum switching time for l9110 so I know that it probably can't handle more than a few kHz. But that's OK.
Please don't suggest using a dedicated driver. I'm specifically asking if this particular IC or other H bridge ICs can be used to drive 2 MOSFETs.


texts: Software for system architecture capture

texts:
I work as an electronics engineer and I'm starting to create a new device. This device will be significantly more complex than any project i've undertaken so far and will require close interaction between myself and the other teams/clients.

To better track how elements of the design will work together i want to create a system architecture, showing how power and data is passed through the device. I've started to do this in MS Word but i fear that the limitations of this could cause errors to arise in the design.

Does anyone have any experience with using any other software packages for creating a visual representation of their system architecture?


texts: Waterproof capacitive touch-sensor issue

texts:
my goal is to develop a waterproof capacitive touch-sensor.
In many sources on the internet, it is said that a mutual-capacitance sensor can achieve this.
For example, in the TI Designs: TIDM-1021 Liquid Tolerant Capacitive Touch Keypad Design application note: https://www.ti.com/lit/ug/tidue90/tidue90.pdf?ts=1598517326899&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FTIDM-1021
We can read on page 5: "The increase of Cmutual causes the measurement result to go in the opposite direction of a touch, and this opposite result is called a "negative touch". This "negative touch" behavior helps to prevent false touch detection when liquid is present."
This phenomenon is also illustrated on figure 19 on page 18.
As the TIDM-1021 used in the application note part is no longer available, we are using a similar part which is the BOOSTXL-CAPKEYPAD. It also works with mutual-capacitance sensing, hence we expect to achieve the same results.
However, it does not work: water on the sensor causes the mutual capacitance to decrease and hence causes the measurement result to go in the same direction of a touch. No "negative touch" is present and hence we cannot prevent false touch detection due to water.
We use the CapTIvateDesignCenter to monitor the measurement result. Here is what we get:
First with a dry touch:

And then with a water drop:

The idle state of the signal lies at the +400 level. As you can see, the effect of water drop is weaker than the effect of a dry touch, but still goes in the same direction (an increase of the measurement signal, meaning a decrease of the mutual-capacitance).
In our setup, we are using:

the BOOSTXL-CAPKEYPAD,

the CAPTIVATE-PGMR to program the board and monitoring signals on our computer. It also powers the board from the USB-bus.

In the application note, they also use a CAPTIVATE-ISO but it is written that if the system is powered from the host PC, there is no need for the CAPTIVATE-ISO board. So it seems OK. Our power supply is then not grounded to earth ground, but page 11 specifies that it has an influence on sensitivity only (which is not the issue in our case).
Something seems interesting on page 5 and may be an hint: "The amount of grounding path around the sensors. Liquid couples the sensor to larger grounding path reduces the mutual capacitance and causes the measurement result to go the same direction as a touch." But I don't really understand what it means and what can we do about it.
The layout is given here: http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/CapTIvate_Design_Center/latest/exports/docs/users_guide/html/CapTIvate_Technology_Guide_html/markdown/ch_evm_boostxl_capkeypad.html#layout
I don't really understand it, I suppose the top black area is a ground plane, but then the electrodes are far away from it, so from where could come the grounding path?
Thank you for your help.


texts: why in some circuit there is use of bubble followed by bar?

texts:
It is a circuit of ring counter. The clock here is negative triggered. but for set and clear it use bubble with bar.What is the need of bubble followed by bar. why it can not use a PRE and CLR (without bar) without bubble. Because both give the same result.

Is there any specific reason for choosing bubble and bar both?


texts: How to distinguish between clock stretching and MSB in I2C EFR32FG14

texts:
In diagram shown bellow of si7021 we have clock stretching phase and MSB phase,
I know we have a flag register I2C_IF ,but how do I see when one ends ant the other starts?
How do I distinguish between the two?
Thanks.
https://www.silabs.com/documents/public/reference-manuals/efr32xg14-rm.pdf
https://www.silabs.com/documents/public/data-sheets/Si7021-A20.pdf


texts: How does the TCP/IP stack interact with Wifi components?

texts: I'm trying to transition beyond Arduino and I'm trying to learn how to use an RTOS (like FreeRTOS) to connect to the web via Wifi. It seems that FreeRTOS and ZentriOS and other RTOS supply TCP/IP stacks. Correct me if I'm wrong but It seems to me that this TCP/IP stack provides the API for interacting with the outside world through either Ethernet or Wifi. Is the Wifi Driver what interfaces the TCP/IP stack with the Wifi Module itself? Does the Wifi Driver implement standard TCP/IP interfaces? Or is it the firmware developers job to figure out how to interact a TCP/IP stack with the wifi driver?


texts:
I’m trying to replace what I believe to be a glass zener diode which I determined was overloaded in an electronic automobile delay module. Cathode was attached to a PCB (labeled “Z1”) and the anode was soldered directly to one of five “blades" which extends through the module and to the female plug of the module bank. While the diode was a bit damaged, I was able to read alphanumeric codes. They are as follows:
PH
3ZX
79C
35*
I’m fairly certain of accuracy, but the cathode side was charred enough to make any characters illegible if there were any. I don’t think that was the case, though. The “35” could be a “36."
The module is of European manufacture—Pektron.
Any help would be appreciated!


texts: Different colors for Power Transmission Towers

texts:
I have observed that some areas have some power transmission towers painted in Red and white colors. But, more often, transmission towers are unpainted. An illustration of what I mean by this,

Left: red and white tower, right 'regular' tower
If I am right, radio/cell-phone towers are usually painted red and white, but the example in this picture is clearly not a radio tower.
So, what is the significance of a transmission tower being painted in such colors?


texts:
I've recently been playing around with analog video like composite to S-video and VCR related things like that. I've always thought it would be really cool to create some kind of analog video generator from sound.

If anyone could explain how composite video signals work and should look that would be great.

Some inspiration is from the "Atari video music" https://www.youtube.com/watch?v=BX1LVBLUYNs
I also have seen people make "Dirty video mixers" which is sort of the path I want to go down.

What I haven't seen is a guitar hooked into a TV. Is it possible to convert a guitar signal into a signal that resembles RCA video? Possibly an arduino could be a good way to go? All analog would be cool though.

Thanks alot for reading.


texts: How to choose proper power supply for 8 servos on Adafruit shield with Arduino Uno controller

texts:
I use Adruino Uno micro-controller powered with USB 5V from PC and  Adafruit 16-Channel 12-bit PWM/Servo Shield on it with 1000uF capacitor, powered with 6V 2A power supply.

Seems like it is not correct power source. Need your help to choose single proper power adapter. I use 8 servo motors:

6 units of Power HD High-Speed Digital Micro Servo DSM44:

Stall Torque: 1.2Kg.cm (16.66 oz-in)@4.8v | 1.6Kg.cm (22.22 oz-in)@6v
Speed: 0.09 sec (4.8V) │ 0.07 sec (6.0V)
Operating Voltage: 4.8 ~ 6.0 DC Volts
Digital: YES

and 2 units of FEETECH Mini Servo FT1117M

Stall torque @ 4.8V: 3 kg·cm | @ 6V: 3.5 kg·cm
Speed: @ 4.8V: 0.13 sec/60°  | @ 6V: 0.11 sec/60°
Digital: NO


texts:
I've got an assignment to make some kind of alarm. When user presses the push button, 1kHz sound should be generated and outputted on some kind of speaker (I'll use buzzer).

That part I know how to make. I can use NE 555 to make astable to generate 1kHz output. But other part of the assignment is the problem. Is says that duty cycle should change from 50% to 0% while user is holding the push button ... I don't even have an idea what to try ...

EDIT: Duty cycle should decay from 50% to 0%.


texts: Is ok to use a CMOS Analog multiplexer with voltage from a sensor as an input?

texts:
So, I got an analog circuit with an IR sensor that generates a voltage in output. The voltage is a measure that must be read with a microcontroller (I use Arduino Zero). This is the sensor.

As you may see from the datasheet, they suggest using a TSV991 in output.

Now, because I would like to use multiple sensors and one analog input on the Arduino, I came up with the idea of using an analog multiplexer. I found out this, the MAX4734 that seems very good for my application (the vary low power consumption is a must for me).

Now, I was wondering if, using such a device to select the input on the analog port could impact on the actual voltage I need to measure from the sensor. I was told to check also the max current the multiplexer can accept to avoid any damage or malfunction. According to the datasheet it "handles rail-to-rail analog signals" so, it should be ok, am I right?


texts: Is thermal relief needed for wire-bond process?

texts: I'm familiar with designing boards for SMT, but less familiar with the wire-bonding process.  When designing PCB pads that will be attached to using a wire bonder, are the pads supposed to have thermal relief?


texts: How to calibrate ACS712 current sensor for a 3v3 MCU (Adafruit Feather M0 with LoRa module)?

texts:
This is my first question in Stack Exchange. I'm completely new to Electronics, but I hope my question is meaningful.

I'm in the process of measuring voltages and currents in my off-grid solar PV setup. We'd want to monitor the PV system remotely, so we're developing a LoRaWAN based IOT setup. We've chosen Adafruit Feather M0 with LoRa module because it has got LoRa module, and it is programmable in Arduino IDE.

I was able to design the simple circuit - voltage divider for Voltage, and ACS712 for Current. I'm facing problems in calibrating the ACS712 sensor with Adafruit feather M0, which is basically a 3v3 logic based MCU.

The specific problem I'm facing is that the 3v3 MCU makes the calibration logic a challenging one. All the articles and YouTube videos I've seen (https://www.youtube.com/watch?v=lisprJs5sNU&t=320s and https://www.youtube.com/watch?v=LGM8v1b41So) are concerned with using ACS 712 sensor interfaced with 5v logic based microcontrollers. I'm wondering if I just have to replace 5v with 3v3 or I've to make any other calculations, to make it relevant for 3v3 MCU. I mean to say, incase of 5v MCU, 0 to 1023 is equivalent to 0 to 5v. Will the logic be the same in case of 3v3 MCU, i.e., whether 0 to 1023 is equivalent to 0 to 3v3 in a 3v3 MCU?

Any response is highly appreciated. If any of you have used ACS712 current sensor with Adafruit M0 LoRa boards or any 3v3 MCUs, please share from your experience. Many thanks in advance.


texts:
I want to connect a microSD card in my AVR ATMEGA32, through SPI, which its operate with 5V.
The microSD card i think that operates with 3.3V so, it is must to connected via bidirectinal level translator.

I found this TI's translator http://www.ti.com/lit/ds/symlink/txs0101.pdf
. which its accepts any voltage from 1.65V to 3.6V in input A, and 2.3V to 5.5V in input B.

My matter is: Can i direct wire the chip's I/O between AVR and microSD?
or it's only, as the datasheet say, "for open-drain and push-pull applications"?


texts:
I know that after time due to writing/re-writing memory wears out, and I was reading about a microcontroller from TI which uses "wear leveling" to insure the longest life of some EEPROM that the chip used.

I can infer that this will try to write to all of the bits on the chip in some sort of cyclic mechanism so it's not constantly writing/erasing some subset of bits at lower addresses and wearing them out faster.

What I'm really curious about is how does this "wear" happen? What components that make up memory are actually wearing out? My very rudimentary understanding is that computer memory uses latches, or caps, or some such component to retain voltage. If that's correct, do they "just stop" holding voltage after a time?


texts: 32U4 based board sometimes does not run setup

texts:
I have a custom PCB using 32U4.
Sometimes when I switch the board on, the code of setup() function does not run. But this is quite unfrequent, the board usually works fine. This just happens from time to time.
I have tested with minimal arduino code just lighting up a LED during setup() nothing more.
Bootloader is Arduino Leonardo.
Here is the board schmatics :


texts: DDR1 Layout Considerations - DOs and DONTs

texts:
I am novice to high speed design.

Before getting in to DDR, I recently learned about impedance matching and how it is done, likewise I learned about length matching and how it is done.(Baby steps towards Signal Integrity)

Now, I need to Place and Route a DDR system within 50x40mm. I have been asked do to it in six layers.

What are the things I will have to learn before doing this? The document I am currently using for reference is AN2582 from FreeScale Semi. Frankly speaking, I dont understand many terms and technologies mentioned in it.

So please list out the points crisply, books and links would be helpful.

Specifically I am looking for suggestions on:

1.StackUp(Gnd, Power Plane location) with reference to Impedance matching(if necessary)

2.Routing principles I will have to follow:

2a) what are the signals that needs to be Length matched in my circuit(details given below). There are 3 to 4 signals falling under the category of address and data group(adding more to my confusion).

2b) routing considerations on address, control lines.

3.Checklist after completion of the entire design.

The third screen shot illustrates signals from Processor.(Kindly zoom-in for part numbers and bear with me)

The crystal used as clock source for Processor is 13Mhz(low speed board isnt it?)

At this time, I have no idea about rise time .

Thanks in advance.


texts:
So since I do not have a battery balance thing yet I have been working, starting yesterday, on some li-ion cells because I need to find capacity of the cells. And I have a few questions to make sure I am doing my math right.

Discharging

I am using 4 computer fans to discharge the cell. Each fan pulls .18 amps. But there 12v fans and this is a 4v battery. So is the fan still pulling .18 amps a hour? And there is 4 in parallel to pull .72 amps a hour. So how much are they pulling because I am simply not sure. And is there a formula on figuring that out? What would it be? Along with the pull I have a multi-meter on the battery to watch the voltage. There at 4v and discharging to 3v. But have nothing to charge them bringing me to my next part.

Charging

The only thing I have is a 5v 1 amp a hour wall charger for a phone. I stripped the wires. All I was thinking of doing was having that directly on the battery and again using a multi-meter to watch the voltage and then stop at 4v. But how long would I expect this to take? Say the battery could hold 2 amps. It would then take 2 hours to charge but I worry that would charge to 5v. So how do I calculate how long it would take to charge to 4v?

The whole purpose is to find the capacity of the battery. Also note these are about 5 years old. Some are good some are not good. Brand new they where able to hold about 2A


texts: Would it be possible to identify the IC from this image (18507CT)?

texts:
Can someone recognise the IC from this image, or the make based on the font or naming convention used?

The top reads F1823 towards the end
The bottom reads 18507CT. Tried looking up these numbers on Google but none of the results correlate.

This IC is inside this device. It's a water flosser that has a motor controlled by a two modes and a speed function. More pictures of the PCB here


texts: How to control motor (1.5 V at about 0.5 A) with Particle Photon using optocouplers and transistors?

texts:
I’m trying to control a motor that runs at 1.5v at ~0.5A using a Particle Photon. I’m powering the Photon over USB (for now, at least) and the motor with a AA battery. I’ve tried designs based off this schematic (modified to power the motor with the battery) but ended up with unacceptable noise in a separate circuit connected to the Photon. I’ve also tried this design without success. I’m a total noob at this stuff so any help would be appreciated.
I have an inexhaustible supply of resistors, a variety pack of transistors and diodes, some small capacitors, and PC817 optocouplers at my disposal (along with some other misc. components).
I’ve read this but most of it went over my head.


texts:
This is a controller board for a home ventilation system. It runs fine most of the time but sometimes the ventilation stops for one minute, then starts again and runs normally for anywhere between one minute and many hours.

Internet search results indicate that the two capacitors are at fault; the system works again for other users after they have replaced those two capacitors (1000uF25V, 1000uF50V,) so I am going to replace these two capacitors even if they visually look fine. I figure that even if they are not the cause of the failure, getting new ones won't do any harm.

1) Replacements are listed as e.g. 5000 hours lifespan.
a) That sounds awfully short for an always-on system. I don't want to fix this problem over and over.
b) Could I use solid-state equivalents instead; would that give a longer service time of the  repaired board?

However, looking at the board it seems there is (was?) a heat problem nearby, but not right there. The reverse side shows that spot more clearly.

2) Could it be that the problem is not those capacitors at all, but rather another component? I can solder, but electronics is not my strong point so I am clueless how to identify and troubleshoot. From the discoloration on the reverse side, it looks like three component became hot (marked red in the third image): IC "78L05A", resistor "3321", and the transistor "BD438". Does this discoloration indicate a failure or is that expected with normal use?


texts: generating 40 MHz clock from 50 MHz in VHDL

texts:
In VHDL how can I get a clock frequency of 40 MHz if my onboard clock is 50 MHz. I know how to divide the frequency by integers but this case is dividing by 1.25. I am using this for VGA so I think it's important that it is precise.
thanks!


texts: 4 wire RTD (PT100) in a wheatStone bridge

texts:
I want to connect a 4 wire RTD PT100 in a wheatStone Bridge. I tried searching on internet but only up to 3 wire configurations in bridge are available or circuits using other ADS IC's are available. But I want to do it in a Bridge Configuration.

Can anyone suggest how I can do it?


texts: Is my mosfet IRF540N OK ? Help to understand MOSFET behaviour

texts:
I am new to using MOSFETs. To help check the MOSFETs, I made a small circuit as in the schematic below on a perforated board. My test MOSFET is IRF540N. Supply source is a Lead Acid battery of 12V.

I am keeping \$V_{GS} = 0\$V (switch open). I expect when I apply the source, the MOSFET will hold and hold forever, as the supply voltage is well below the Breakdown Voltage.

But, I see the voltage across DS slowly falling and voltage across \$R_1\$ slowly rising till the voltage is about equal across \$R_1\$ and the MOSFET. Then it rises too. This keeps repeating.

If I short \$R_1\$, the MOSFET will blow in 1-2 min.

If anybody can help me understand where I am going wrong, that will be greatly appreciated.

simulate this circuit – Schematic created using CircuitLab


texts:
I want to power a computer fan from a 12v motorcycle battery.
Disregarding the motorcycle battery being 12.6 volts (not charging), lets say that it's a regulated constant voltage source of 12 volts.
The fan needs to be 12v driven where 0.58 Amps will be drawn.
It is a very old fan, and I can't find a datasheet. But it is exactly this one:
https://www.ebay.com/c/1472102822
Ohms law says that a 24 ohm resistor is good for 0.5 Amps or current. However, Ohms law also says that the power being drawn will be 6 Watts. Most resistors do not have this high of a power rating.
How do I power my computer fan the right way without getting a high wattage? I am not looking forward to using bulky, high wattage resistors.


texts: Triggering BT139 triac with MOC3063 opto triac

texts:
First time poster having some problems with triggering triacs. I'm well aware of the dangers of working with mains voltage and I'm very careful.
I'm using one BT139-800 triac to switch a 35W single-phase motor and one triac for switching 3 ballasts for 6 fluorescent lamps with total power of 108 W. I'm triggering the gate of the BT139 with MOC3063 opto triac. I'm using the circuit below for both loads with the noted resistor and capacitor values.

The problem I've encountered is that when I connect the circuit to the mains both triacs are already triggered and conducting. I've started debugging by removing the opto triac which did not solve the problem so after that I've tried removing the 360 Ohm resistor between gate and terminal. Obviously the triac did not conduct and I was able to trigger it with carefully shorting the pins with a screwdriver. Thus I figured the problem is in the resistor, but I'm not sure what its value should be. Is there an easy way of determining the correct value? Are there any other problems with the circuit?
Also how do I know that the snubber circuit has correct values? The motor has a 2.5 uF starter capacitor. I guess I could eliminate the snubber circuit for the fluorescent lamps since the ballast has a power factor of 0.98 and the opto triac is zero-crossing. Is that correct?


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I assume the reader is aware of how a DPLL works.

The DPLL oscillates with a frequency of \$F_{out}\$.
The DCO free running frequency is \$F_{free}\$.
In the model of our DPLL we've only considered the TDC quantization noise.
The instantaneous frequency deviation is given, which is the change from \$F_{free}\$ to any frequency we want it to lock onto, say \$F_{out}\$. The following plot shows a 1MHz change until it locks:

where CKR with the average frequency \$F_R\$ is the retimed clock used to synchronize the internal DPLL operations. The index k represents the kth occurrence of the CKR's rising edge. Let's say that this curve is stored in a vector called ifd, which has a length of k, obviously.

Now given the frequency deviation I'm not sure as to how I could find the power spectral density of the output phase noise, which is mainly due to the TDC quantization with a limited resolution.

I understand that the phase is the time integral of the frequency multiplied by 2\$\pi\$, or \$\phi=2\pi\int{ifd \ dt}\$. We know ifd so we know \$\phi\$ by integration. Now in the context of MATLAB language the PSD is obtained

phi=2*pi*cumsum(ifd)/FR;
pn=f(phi);
% PSD
fs=10*FR;
[pxx,f]=pwelch(pn,[],[],[],fs,'onesided');
XdB=10*log10(pxx);

I'm actually stuck at the second line, where I don't know what f should be. Does anyone know what I should replace f with? Is that simply a sin function or something more complex than that?

Thanks for your attention,


texts: What's the difference between NPN and PNP transistors?

texts:
Suppose that I know how an NPN transistor works.

How different is a PNP transistor? What are the operational differences between a PNP and a NPN?


texts: How does the hardware realize adding 8 values in 1 clock cycle?

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For example:
result= a1+a2+a3+a4+a5+a6+a7+a8

How many adders are needed to perform this in 1 clock cycle?
What does the design look in terms of hardware?


texts:
I am confused with the above problem. I have shown my attempt.
I doubt the equation x1 = x1 + u. Please help me with this problem.


texts: How to properly constrain generated clock and synchronizer in Altera Quartus?

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In my Verilog design I have a 25Mhz board clock from which I derive a 100Mhz clock. Coming from an external Pin I have an asynchronous 4.77 Mhz clock which should drive the logic and be synchronized before (using the main clock):

always @(posedge clk_100Mhz_i)
begin
    // Synchronizer chain... hopefully
    clk4_del0 <= clk4_77_i; // SysClk from ext pin
    clk4_del1 <= clk4_del0;
    clk4_del2 <= clk4_del1;
end

// Used to clock internal regs
assign clock_4_77Mhz = clk4_del2;

// Sample
always @(posedge clock_4_77Mhz)
begin
    timerIdx <= timerIdx +1;
end

Unfortunately I get the following warning:

Warning (332060): Node: X8255_top:x8255|clk4_del2 was determined to be a clock but was found without an associated clock assignment....

I also get a warning about an unconstrained clock. I tried to use what the Timing Analyzer suggested and added the fourth line to my .SDC:

# Constrain clock port clk_25MHz_i
create_clock -period "25.0 MHz" -name clk_25MHz [get_ports clk_25MHz_i]
create_clock -period "4.77 MHz" -name clk_4_77MHz [get_ports clk_4_77_i]
create_clock -name {X8255_top:x8255|clk4_del2} -period 210

without success.

What am I doing wrong?


texts: What is internal battery dc voltage and how do I calculate some battery specs?

texts:
Editing this old question for accuracy in case anyone else sees this. Removed incorrect calculations. Also, I don't think it was ever answered what internal battery DC voltage is. Any ideas?

So what I know is

that the battery is a 13.5 [kWh] battery assuming a discharge/charge
rate of 3.3 [kW]
The DC voltage range is 350-550 [V]
The internal battery DC voltage is 50 [V] (what is this???)
Continuous current is 14.3 [A]
Power (continuous) is 5 [kW] (charge/discharge)

Here's what I don't know:

What internal battery DC voltage is
If the DC Tesla PowerWall 2 has a limit to how many PowerWalls you can stack in parallel (pretty sure this is a manufacturer question so you can ignore this one)
Why the AC Tesla PowerWall 2 specifies a limited number you can stack (I do now know that inverters usually have a limit to how many you can hook in parallel unless they are grid-tied, and I'm pretty sure this is a manufacturer question too so you can ignore this one).

Here's what I want to calculate with the information I have (need this information for a program called HOMER legacy):

Nominal capacity (in amp-hours)
Nominal voltage for DC version

Data sheet link: https://docs.google.com/viewerng/viewer?url=http://www.solarquotes.com.au/blog/wp-content/uploads/2016/11/Powerwall-2-DC_Datasheet_English.pdf&hl=en_US

AC Version: https://docs.google.com/viewerng/viewer?url=http://www.solarquotes.com.au/blog/wp-content/uploads/2016/11/Powerwall-2-AC_Datasheet_English.pdf&hl=en_US