texts: MAX608 boost converter stopped working, the OUT pin is shorted to ground

texts:
I was working on a little project to convert 3.7V from a lithium ion cell to 5V using a MAX608 boost convertor IC.
I put the required components according to page 7 of the data sheet and everything worked fine, and I was able to get a good 5V output with reasonable voltage ripple under load.
I was experimenting with different inductor coils, and filter capacitors, for a few days before deciding to solder the circuit to a perf board and see how it works.
Today for some strange reason the MAX608 stopped working properly. I quickly checked the output voltage and it read about 3.5V, I checked the chip and saw that it was getting hot quickly, so I removed it.
I double checked the connections according to the schematic, and even replaced the components with new ones.
I also replaced the battery with a new one, fully charged to about 4.2V, but the MAX608 refused to work and got hot quickly, and I quickly removed it.
I am beginning to suspect that the chip might have been damaged. I removed it and did a quick continuity check with my multimeter, and to my surprise I found out the OUT pin and GND were shorted, I heard a clean and loud beep. Is this normal?
I am thinking it isn't, since according to the data sheet the OUT pin is connected to the non-inverting input of the internal low voltage start-up comparator.  The inverting input of the comparator seems to be connected to a 2.5V internal voltage source.
<img src="https://i.stack.imgur.com/IJgXE.png" alt="The Functional Diagram of MAX608 according to the data
sheet" />
If this is normal, then what are possible culprits?

Could it be the 3.7V input? Which sounds odd since it is well with in the input range of the chip; 1.8 to 16.5V according to the ELECTRICAL CHARACTERISTICS table of the data sheet on page 2.
I used a logic level IRL3102 MOSFET instead of MMFT3055EL since I do not have access to those MOSFETs; I tried other IRL3102s, but didn't solve the problem. I don't think trying other type of logic level MOSFETs would make much difference either. But I could buy a few and test this.
Could this be a breadboard problem? I tried 3 different breadboards and the result was the same.
Have I possibly damaged the chip maybe by ESD, perhaps by accidentally touching something on the circuit?
I don't have a chip replacement yet, and ordering a new one will take quite a while. Should I change the chip?
At this stage I am out of ideas. What should I check next?


texts: Why is de-assertion of an asychronous reset a problem compared to its assertion?

texts:
"The biggest problem with asynchronous resets is that they are asynchronous, both at the assertion and at the de-assertion of the reset. The assertion is a non issue, the de-assertion is the issue. If the asynchronous reset is released at or near the active clock edge of a flip-flop, the output of the flip-flop could go metastable and thus the reset state of the ASIC could be lost."

Source: Page 18 , section 5.4 of http://www.sunburst-design.com/papers/CummingsSNUG2003Boston_Resets.pdf


texts: I have no idea should I connect Vin(-) input pin to COM output pin in this converter. Both pins are somehow grounds. The converter works in both cases, but what is the proper way?


texts:
I am working on a low frequency 30 khz module that needs to have an ultra low power consumption. The problem is the research focuses on improving the performance of the adders and multiplier and doesn't focus on the power consumption.

Could some one tell me what are the best architectures for multipliers and adders to have the lowest power consumption in nW?

Let me put my question in an other form: What is the adder and multiplier architecture that achieves the lowest power consumption so I can build them using vhdl, knowing that the delay is not an important issue.


texts: Centre tap transformer unknown rectifier citcuit

texts:
I have an older transformer with a rectifier circuit what I managed to backtrace and looks like this:

I could not find a lot of details about this online but it seems the transformer can supply 2x2x24V.

Can someone explain this rectifier circuit? It looks to me this is 2x half way rectifiers on both end but what is the diode in between the two serves for?

Is it safe to connect the 2 32V outputs in series to maximize the voltage?

Thanks?


texts: hall current sensor potential failure mode

texts: I was curious what are potential common failure modes for hall-based ac current sensors in a mains ac environment? Specifically those like the acs712 and acs723. Assume you have a 5amp current sensor, and draw 20+ amps of current through it for a sustained period of time. What would happen?


texts: New to debugging. How to go about finding a mistake in this exponential voltage converter

texts:
This is the exponential converter I'm trying to set up:

Marked in purple are the measurements I have taken. As far as I can figure out the first part is working correctly OpAmp is giving the expected output proportional top input voltage. The second part with (-0.74,-0.77,11.39) measurements don't seem to to change with input voltage. I have checked everything 10 times and not sure how to go about debugging this.
I 3x checked every resistor value and replaced every OpAmp and transistor just in case of damage.


texts:
I'm trying to calculate E12 resistor series myself.

Above is an illustration of the idea where such equation can be written:

x = r3 + r3 * %tol = r4 - r4 * %tol

form that we can derive:

r4 = r3* [(1 + %tol)/(1 - %tol)]

hence in generalized form we can write (%tol = 0.1 for E12 series);

r(i+1) = ri* [(1 + %tol)/(1 - %tol)]

But when I iterate the above formula in a for loop I obtain the following results for the first resistor values:

1.0000    1.2222    1.4938    1.8258    2.2315    2.7274    3.3335    4.0743    4.9797    6.0863    7.4388

Then I take [(1 + %tol)/(1 - %tol)] = 1.2 rounded value instead of 1.222222 and write the formula as:

r(i+1) = r(i)*1.2

But again when I iterate the above formula in a for loop I obtain the following results for the first resistor values:

1.0000    1.2000    1.4400    1.7280    2.0736    2.4883    2.9860    3.5832    4.2998    5.1598    6.1917

But the real values for E12 should be as:

1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8

What am I doing wrong here?


texts:
I have a power supply, multimeter, and a copper wire  with cross sectional area (A) A= 2.14*10^-3 m^2, Length L = 0.13 m and the resistivity of copper is p=1.7 × 10-8. The goal is to find the resistance of my copper wire, but I'm not sure what other instruments I need to determine the resistance, or how to setup the circuit to find out the resistance. After using the resistance equation, I found that the resistance should be about 1*10^-6 (ohms), but I cant get close to that answer.
How should the circuit be setup?


texts:
simulate this circuit – Schematic created using CircuitLab

How to calculate Iout(current flowing through RL) of this circuit?
All Resistors are of same value except the load resistor.
Let the rail voltages be +15v and -15v.


texts: Inverting Op Amp Finding resistor value of voltage divider

texts:
A small clarification V_2 = -100V_1
I don't think my analysis is correct since I ended up with R1 as a denominator.


texts: Blue light LED works without any resistor and doesn't burn out. Why?

texts:
I just started to learn electronics and LED in particular. What I've read in literature is that you MUST have a resistor, otherwise your light LED will die, since the LED current is ~20-30mA, and the current from the 4AA batteries is definetely >3A (it burned the 3A fuse instantly).
My circuit shown in the picture

Why the LED works and not burned down instantly? What could it be? And does it work for most of LEDs, or I just happen to have the one with higher power dissipation, or something like that?


texts:
I'm trying to repair a laptop motherboard for a coworker and found a shorted IC.
I'm not sure of what it is so i'd like to know if anyone could give me an hint

The IC is labeled 5AF2S and is in SOC70-5 package.

I found out it could be a 3 state non inverting buffer but I'm really not sure.

The motherboard part number is byg43 nm-a601

Edit:
Here is a picture i had in my phone.
The red circle is the ic try to identify
The green circle is something that is gone too ( it only hangs on one leg and show marks of corrosion )

Edit more picture

This last one is the green circled part of the first picture
Marking is FAL CO it is a zener diode DFLZ5V6-7

Edit: I just bought the schematic
It is a power distribution switch G517F2T11U
https://datasheet.lcsc.com/szlcsc/1912111437_GMT-Global-Mixed-mode-Tech-G517F2T11U_C356801.pdf


texts: 8b10b encoding: Calculating running disparity for multiple words

texts:
I am designing a 8b10b encoder in SystemVerilog. The circuit has the ability to encode 1-16 bytes (8 bits/byte) in a single clock cycle.

I have a question regarding calculating the running disparity (RD), which is a single bit output. I understand it represents the difference between no. of ones - no. of zeros in a bit stream. Neutral disparity implies difference is 0.

The calculation is straightforward when the input is a single byte. But if I have 3 bytes to encode at once, how do I go about calculating RD?

First, I encode each byte separate to form a 30b output.
Do I take the 30b (3x10) encoded output and calculate RD, i.e., RD(out[29:0])?

Or

Do I calculate RD(out[9:0]), RD(out[19:10]), and RD(out[29:20]) separately and then decide whether to maintain or invert current RD?

Thanks.


texts:
I want to build a counter circuit which to count from from 0-7, during some pulseswidth. The problem I am having is that it has to do the whole count sequence during one PW and that is where I am struggling to come up with an idea

edit: just want to delete question now, sorrry for irrelevance and being unclear


texts: Why do you need two voltage sources in a switched capacitor realisation of a continuous resitance?

texts:
I am learning about using switched capacitors in RC circuits to create effective resistances.
When I run through what is happening in my head, I consider the potential difference as (V2 - V1) or V effective. Since this is the case, what is the need for two potential differences, V2 and V1. Would the circuit not be the same with a single battery of V2-V1?


texts: Calculate Current out of Function Generator

texts:
I couldn't find an equation for this on Google/Wikipedia, but does the frequency of a function generator (we'll say that it's a sine wave) impact the current output. Example, if I had a 5 volt source and applied it to a 10 ohm load at 50Hz what would be the current seen by the load?

Thanks,


texts: Bode Plots and Electrical Circuits - Zeroes and Poles

texts:
I would like to understand more electrically with little math (transfer function) involved regarding Poles and Zeroes in a control system (Feedback in DC-DC Buck Converter to be specific). I understand that I have been told my math users in this site that I will not understand the concept of poles and zeroes without having transfer functions or math. But request you all to help me understand electrically about this.

How does a having pole/zero in a system mean and how does this pole/zero impact electrically?

And how does a having a pole decrease the gain in the bode plot and how does having a zero in the bode plot make the slope of the line flat? Request you to provide answers in more simple and basic electrical terms as much as possible. I don't know if this is appropriate, but please excuse if so, "Please explain it to me like a five year old" (Maybe an analogy)


texts: Phasor math for balanced 3 phase circuit

texts:
Are there any mathematicians in here?  I am currently reading my ECE text's chapter on AC machines and i referred to some material in the chapter that first discussed AC circuits.

In the photo below of the math, I am unsure of how on the right hand side, the subtraction of two phasors became a multiplication of 2 phasors...  Specifically, following the red arrow, how did the term furthest to the right go from the form it had I*<150-theta to (1 - 1*<120) ??

I do not recall seeing this anywhere else in the chapter or on the review of complex arithmetic in the appendix and it is sort of bugging me.  I am not seeing how they got from that line to the next line in the solution process.


texts: Detector of a 1 followed by 1 in a sequence of 0s

texts:
I need to design a digital circuit that detects when a sequence of 0s does NOT contain a 1 followed by 1 (or more).

Example:

00000000010001000000000 Output: 1

00000011000000010000000 Output: 0

I know how to design a sequence detector, but this case is a little bit different since it needs to check the whole sequence before giving an output.

Thank you.


texts: Will two 18650s in parallel double the total max continuous discharge current?

texts: Let's say a 18650 cell is rated at max continuous discharge of 8A . Will having two in parallel make it 16A?


texts: What makes Bluetooth v5.0 completely better than v4.2?

texts:
I read documents about Bluetooth 5.0 and one of my first sign is, v5 has longer range, higher speed and also consuming lower power than v4.2 . Actually these features should affect each other by opposite way. If speed and range is better, then power comsuption should be affected in a negative way.

Whats the actual change they did to make 5.0 better than older one. Every feature of it seems better ? Its about data structure ? Whats the key improvement ?


texts:
I recently posted a question about cutting the ground wire in an isolation transformer to make it truly isolated. After reading the responses, I decided the best advice was to reconnect the ground wire and just use a three prong to two prong adapter between the isolation transformer and the DUT. After I reconnected the ground I checked and confirmed that I had ground wire continuity from the wall outlet to the transformer outlet. Then, just out of curiosity, I plugged in one of those outlet testers from Home Depot (the ones with the three lighted indicators that tell you if the outlet is wire correctly). I expected that it would say that I had an "Open Neutral" since there is no connection between primary and secondary coils, but what it said was that I had "Open Ground". I checked the tester in a house outlet and it is functioning fine.

Is there some physics about transformers that would confuse this tester or is it telling me that even though I think I have good continuity through the ground wire, it isn't good enough?


texts:
I understand that three phase allows you to always have a voltage, when another phase is in neutral, other phases will be at maximum peak.

What I don't understand is how three phase's add up? If all the phases are separated 120 degrees apart, however they all reach maximum peak in one cycle, and lets say each phase is 5VAC Would it be 15VAC per cycle since they're all reaching max peak in one cycle? Just overlapped 120 degrees apart.


texts: Capacitors bridging over transformer in insulated power supply

texts:
I need an isolated power supply for powering a device that’s very sensitive to current leak (see below). I bought one such isolated power supply from Aliexpress. What surprised me is that there seem to be two capacitors bridging the isolating transformer.

I wonder if these two components somewhat undermine the “isolation properties” and if I should perhaps remove them? What are they there for anyway?

BTW the black rectangular component adjacent to the top side capacitor on the first photo is an optocoupler so that should be ok.

FYI the sensitive device is an Atlas Scientific pH probe measuring my pool pH connected to a Raspberry Pi. Apparently the current leak between the mains switching 5V powersupply and the pool water is enough to completely throw off the measurements. When the RPi is powered from a battery power bank it gives accurate results.

Can / should I remove the two blue things?


texts:
This is with reference to  a circuit i saw in The Art of Electronics.The authors claim that IC1 is an integrator and that the circuit ensures that a current of magnitude |Vin|/(200k) constantly flows through the capacitor.They further explained that only the direction of current changes at regular intervals determined by the Schmitt trigger IC2.

I suspected that the opamp IC1 is a comparator(no negative feedback).So I simulated the circuit with LT Spice (with Vin =6 Volts) giving me the following results.

The waveform in green is the voltage at inverting terminal of opamp IC1.The waveform in red is the voltage at the output of IC1 and the blue waveform is the current through capacitor C1.The simulation proved that the authors were indeed right!!
The inverting input was held constant at 3 Volts(for Vin=6 Volts).

This meant that the capacitor somehow completes the feedback loop providing negative feedback and thus ensuring that voltage at non inverting terminal = voltage at inverting terminal.
 I came to terms with the fact that the capacitor 'completes' the feedback loop.I guessed that since the capacitor conducts throughout the time period ,it must always behave like a varying resistor completing the feedback loop.

But then I had trouble explaining why a capacitor doesn't complete the feedback loop in an astable multivibrator circuit.

The above circuit can definitely be explained by considering the opamp  as a comparator switching between Saturation voltages at fixed thresholds.Simply said- the capacitor doesn't complete the feedback loop.

So to summarize my question -why does the capacitor complete the feedback loop
in the Voltage Controlled Oscillator circuit but not in an Astable Multivibrator???


texts:
I am building an Affordable Solar Radio Telescope and for it I need an amplifier. I have built the circuit described in pg 8 of this link.

I have built the exact circuit but I am using a dual supply of 12 V (because I am using op amp IC 741 and read that it works on dual supply).

But the op amp is providing negligible gain, and even though my input is positive. And I am using non inverting mode my output is negative.

What to do?


texts: Interfacing GPIO pins between a uC and RS-485 tranceiver

texts:
uC: EM357 datasheet
RS-485 IC: sp3078e datasheet

Two input pins on the sp3078e need to go high at the same time when I'm sending bytes.  I'm using a single output pin on the EM357 to drive both of them high and low.  The EM357 datasheet says the max output current for the pin that I'm using is 4 milli Amp.  The max input current on the sp3078e is 1 micro Amp.  Do these connections require any series resistance or pull-up/pull-down?


texts: How to extract pol & zero data from amplifier's data sheet?

texts:
I am looking at the OPA548 amplifier's data sheet and trying to extract the corner frequencies but i am unable to accurately do it, as i can only make assumptions based on the open loop gain/phase graph, so what should i do ?

Link to datasheet


texts: Apparent contradiction in AC analysis of BJT amplifier

texts:
Suppose you have the circuit:

For an AC analysis we can draw the following circuit:

Now my job is to find \$v_{out}\$, which can be easily found by:
$$
i_E=\frac{v_{in}}{R_E} \\
i_C=-\frac{v_{out}}{R_C} \\
i_E=i_C \\
v_{out}=-\frac{R_C}{R_E} v_{in}
$$

And this is reasonable, but one could also argue:
$$
i_B=-i_1 \\
i_B=\frac{i_C}{\beta} \\
i_C=-\frac{v_{out}}{R_C} \\
i_1=\frac{v_{in}}{R_B} \\
v_{out}=\beta \frac{R_C}{R_B} v_{in}
$$

The second one I think is wrong but I can't find the loophole in the reasoning.


texts: Changing coil voltage for Electric Relay - HF14FW/0XX-HSTF

texts:
I have a controller board with HF14FW/018-HSTF electric relay. It's not functioning now, so I need a new one, but apparently an 18 V version is not available anywhere.

How can I adjust the coil voltage, if I buy 12 V or 24 V versions? Or maybe there is an alternative model I can use, with similar characteristics?

Any help or advice is highly appreciated.

PS: It's from the water level controller for an espresso machine, if it matters.


texts: Heating a wire with DC current; why is it hottest in the middle?

texts: I am putting DC current through a wire to heat it. I would think the wire would heat up evenly but I have found that it is hotter the closer I get to the middle, or, respectively, colder the nearer to the clamps. Can anyone explain this?


texts: PIC32MX can't get 80 MHz Clock from Internal RC OSC

texts:
I am using PIC32MX795F512L with the internal RC oscillator. By changing the settings of the config, I can get to 60 MHz max. But I can't get to 80 MHz. When I change the config for 80 MHz, PIC32 just won't run. Here is my config settings for 80 MHz clock speed.

    #pragma config FNOSC =  001            // 001       // FRCPLL       // Internal Fast RC oscillator (8 MHz) w/ PLL
    //#pragma config JTAGEN = OFF         // Disable JTAG
    #pragma config FSOSCEN = OFF        // Disable Secondary Oscillator
    #pragma config OSCIOFNC = OFF       // Enable CLKO Output on the OSCO Pin
    #pragma config FCKSM = CSECMD       // Enable Clock Switching & Fail-Safe Clock Monitor (FSCM)
    #pragma config FWDTEN = OFF         // Watchdog Timer Disabled

    //#pragma config ICESEL = ICS_PGx1    // ICE/ICD Comm Channel Select
    #pragma config FPLLIDIV = DIV_2     // Divide FRC before PLL (now 4 MHz)
    #pragma config FPLLMUL =  MUL_20     // PLL Multiply (now 80 MHz)
    #pragma config FPLLODIV = DIV_1     // Divide After PLL (now 40 MHz)
                                        // see figure 8.1 in datasheet for more info
    #pragma config FPBDIV = DIV_1       // PBCLK = SYCLK

The same config above runs on the Explorer 16 Board. But It doesn't run in my custom designed PCB.


texts: Charging 3P pack of 18650 batteries using a single TP4056, and protection standards

texts:
For a project at uni, I'm trying to learn to work with 18650s and TP4056s. One of the tasks is to be able to USB-charge three 18650s (Panasonic NCR, 3350 mAh each) in parallel, whilst also being able to draw current from the batteries (not when charging; we already have a switching circuit to separate charging and discharging automatically, but this is besides my question).

After days of research, it seems to me that over various forums, people are split on the use of multiple batteries and possibly multiple TP4056 in this regard. I've seen people recommending for and against the use of each of the following three scenarios:

One TP4056 with a 3P parallel pack;
Three TP4056s in parallel with each having one battery;
Three TP4056s in a series/parallel configuration with the first having a 3P pack.

This is an example of people approving the first, this is an example of someone approving the second, and this is what I mean by the third configuration.

All these seem conflicting to me, and so I'm wondering which is considered bogus, and which is considered good practice. Personally, I'm most inclined to go with the first approach, since I don't see why a TP4056 would treat three (balanced) batteries differently from a single battery with triple the single-battery capacity. A diagram of this proposal - not including switching mechanisms as mentioned since those are not fundamental to the question at hand, and therefore assuming the TP's OUT will never be outputting anything when there is current flowing into the IN - is found all the way at the bottom.

I was also told it'd be bad to connect the inputs of three TP4056s in parallel to one USB breakout board, and I don't know what's up with that (I'd be fine in using diodes, if current flowing in and out of the modules would somehow be the problem). This would of course not be an issue with my proposed way of doing things, but it would be for the other two methods.

Furthermore - notify me if this requires me to open a separate question -, this SE thread's accepted answer advises that one connect a protective DW01A in between TP4056s and batteries, but as far as I know, that exact circuit is already present on the TP4056 itself. I have read about there being TP4056s on the market with and without protective circuitry, and I'm thinking this might be what that SE thread is referencing, but I might be wrong about this. Any extra thoughts on this last point appreciated.

Edit: Added diagram. I forgot to add that the charging time is of little importance.


texts:
I'm using burst mode to read 14 bytes from a sensor via I2C running at 400KHz. The problem is that there are periodic errors on the last byte of the packet, that come in roughly every 8 reads. The issue does seem to be specifically related to the last byte, as a current workaround is to simply request 15 bytes instead of 14 (there are registers after the ones i care about, so that works fine).

What could possibly cause this? A couple of things that I'm uncertain about:

the pull-up resistors are 4.7K. I know this is on the threshold of sizing for 400KHz, but switching to smaller resistors doesn't seem to have an impact (tried 3.3, 2.5 and 1.5)
There are what appear to be irregularities in the clock line (see attached logic analyzer screenshot). I'm not sure if that's something or not, but I would expect a clock line to be... well - regular.

I'm using the hardware I2C driver on an STM32 chip.

LA output:


texts: How to add external GPIO interrupts on STM32?

texts:
I'm trying to configure STM32CubeMx to external GPIO interrupts, however, in the NVIC screen I don't see an EXTI... interrupt to be set.

What should I do to be able to e.g. check for interrupts on GPIO pin PB14, PB13 and PB12?


texts: Reverse Polarity in rush Protection 2 p fet parallel

texts:
after reading those links :

Reverse-polarity protection P-channel MOSFET

Optimal method for multiple MOSFETs for LED driving with a shared power rail

Parallel MOSFETs

and this pdf :

International Rectifier - Application Note AN-941 - Paralleling Power MOSFETs

https://www.irf.com/technical-info/appnotes/an-941.pdf

i wanted to know if my design is right ? if it has any problems ?

max Current calculation :
does max current will equal root ratio max power dissipation to max R on ,

without taking in consideration rise of temperature where it is positive coefficient , so if current increase temp increase leading to increasing Ron so current decreases leading to stability this also helps with parallel fet .

max current 2 fet combined will be just summation ?

capacitor sizing :

i want simple calculation of capacitance of capacitor where it will affect in rush current .

my design  :

update 2 :

so i added capacitor parallel to zener for inrush current

study caps values in reverse polarity case :

http://www.mediafire.com/file/ktecx6txuqk5pbn/capacitors_values_reverse_polarity_protection.xlsx/file

i can conclude from these that caps decreases the change of voltage , am i wrong?

what is  p and f values analogue sim y axis means ?

to study in rush current : i have to make current probe right and cancel the current source in schematic ? because i tried this but change of current not appeared ,
should i  make dc sweep voltage ?

is this method  the way for studying in rush current ? :

https://electronics.stackexchange.com/a/352771/237957

i have read here

http://www.ti.com/lit/an/slva670a/slva670a.pdf

buck converters make u dont need in rush current limiter because they have soft start functionality

just wanna make sure that buck converters will do the work ?


texts: I'm learning about superscalar CPUs and I had a question about that and data dependencies. Given the dependencies, RAW  (read after write), WAR  (write after read), WAW  (write after write), when would the ROB (re-order buffer) NOT be used?


texts: Dipole antenna electric field generation

texts:
An antenna that is of half wavelength of a signal is a dipole antenna. When a signal is fed to this antenna, it should induce an electron flow. However, it is also said that this electron flow produces high concentrations of electrons on either sides of the dipole alternatively during transmission. Many literature state that it is this electron flow that creates a fluctuating magnetic field around the antenna.

I would like to now take a second example. Lets take the example of an AC light bulb being lightened by a 230V 50Hz source. The bulb is connected to the AC source through a wire. In this case, does this wire too experience the same effect of alternating concentrations of electrons on its ends? Doesn't the electrons flow continuously from one end of the souse through the light bulb back to the source without having  aforementioned "concentrations" on either sides?

If so, I would like to know how the former scenario happens especially in the case of antennas and not for the second scenario.

source I studied : https://www.youtube.com/watch?v=7bDyA5t1ldU


texts: Radix-4 Booth's Multiplier verilog code error

texts:
I wrote the code for radix 4 booth's multiplier. But, I am getting 2 errors. I am not able to solve it.
Could you please help?
The errors are:

Error: C:/modelsim_dlx64_2021.1/examples/assignment/booth.v(14): (vlog-2110) Illegal reference to net "B1".

Error: C:/modelsim_dlx64_2021.1/examples/assignment/booth.v(35): Range must be bounded by constant expressions.

CODE
module booth_mul #(parameter N=8,M=8,logN=4)(clk,start,rst,A,B,y,done);
input clk,rst,start;
input [N-1:0]A;
input [M-1:0]B;
wire [M:0]B1;
output reg done;
output reg [N+M-1:0]y;
reg [logN-1:0]count;
reg [N+M+2:0]acc;

always@(posedge clk)

begin
B1={B,1'b0};
if(rst==1'b1)
begin

    acc = {N+M+3{1'b0}};
    count = {logN{1'b0}};
    done=1'b0;
end
else
begin
    if(start==1'b0)
    begin
        acc[M:0] = B1;
        acc[N+M+2:M+1] = {N+2{1'b0}};
        count = {logN{1'b0}};
        done=1'b0;
    end
    else
    begin
        if(count<M)
        begin
            case(acc[count+2:count])
            3'b000 : acc = acc;
            3'b001 : acc[N+M+2:M+1]<=acc[N+M+2:M+1] + {A[N-1],A[N-1],A};
            3'b010 : acc[N+M+2:M+1]<=acc[N+M+2:M+1] + {A[N-1],A[N-1],A};
            3'b011 : acc[N+M+2:M+1]<=acc[N+M+2:M+1] + {A[N-1],A,1'b0};
            3'b100 : acc[N+M+2:M+1]<=acc[N+M+2:M+1] + ~{A[N-1],A,1'b0} + 1'b1;
            3'b101 : acc[N+M+2:M+1]<=acc[N+M+2:M+1] + ~{A[N-1],A[N-1],A} + 1'b1;
            3'b110 : acc[N+M+2:M+1]<=acc[N+M+2:M+1] + ~{A[N-1],A[N-1],A} + 1'b1;
            3'b111 : acc = acc;
            endcase

            acc = {acc[N+M],acc[N+M:1],acc[N+M:2]};
            count = count + 2;
            done = 1'b0;
        end

    else
    begin
        count = count;
        done = 1'b1;
        y=acc[N+M-1:0];

    end
    end
end
end
endmodule


texts: Can I place my inductors in parallel to make a Flyback?

texts:
I would like to build a flyback and I've tried simulating my circuit in LTSPICE, in which I coupled a PCH-45X-824 inductor (820µH, 986mA pk) with a 744139 WE-SI inductor (1.124mH, 3A pk).

It works well and provided the output I wanted so I was wondering if I can place the two inductors in parallel to each other on the breadboard/PCB and will it work the same way it did in the simulations?

Thanks!

Edit: I have a 555 pwm to control the switching speed of the mosfet which will control the voltage and duty cycle of the output


texts:
Say i have a controller circuit which has a clock frequency of 100Hz, there are input signals eds,enable,reset which will come from other circuits or a computer, how do i time these inputs to stabilize just before the rising edge of the 100Hz clock in controller circuit?
My thoughts are maybe to use a memory device like registers to store data from external circuit at a different clock frequency to controller circuit, then read the data using a clock frequency with a rising edge just before the rising edge of the controller 100hz clock?
Ive also head FIFO can be used to connect 2 circuits with different clock frequencies, is this any useful?


texts: Power dissipation in resistor from triangle wave

texts:
How to calculate power dissipation through resistor from specific wave form?

Wave:  Triangle, 1V, 1kHz
Resistor: 10kohm

Q: What is the power dissipation in the resistor, considering frequencies up to 5kHz?

Is there a simple and more accurate way of calculation?
In case I would like to understand/learn both.


texts: What do I need to take in account when using a voltage divider as a voltage sensor?

texts: I'm trying to make a voltage sensor (battery input[0-12v] ) with an output of 0-5v with a voltage divider. I'm gonna read the voltage through a microcontroller and  I'd like to know if there is something else in the process I have to add in the circuit.


texts:
This question is in reference to my earlier question:
Resolution gain in Delta-Sigma Converters
What I understand
From the answers I inferred that we need the input to have some amount of noise (to randomize the signal), so that averaging can improve the resolution of the signal. This noise dithering is done by the DS loop in DS ADC. If we use second order ADC instead of first order we are adding more noise so we increase the resolution better than the first order.
But I also read that statistically the uncertainty improvement that can be done by averaging, if the data is completely random is sigma/sqrt(n), where sigma is the standard deviation of the individual measurement and n is the number of samples we are averaging.
So averaging four samples, for instance, would give me an extra 1 bit accuracy as the uncertainty would be halved.
Question
Is the above understanding correct? By increasing the order are we trying to reach this maximum uncertainty improvement limit by trying to randomize the data better, thus, for instance, 1 extra bit if we are using averaging of 4 samples? In other words, is 1 bit increment in the resolution the maximum that can be achieved by averaging 4 samples for any kind of ADC be it normal Averaging ADC or DS ADC?


texts:
I have a question regarding an application with a Modbus RTU network.

I would like to know if it's possible to use a CANbus cable instead of an RS-485 cable? Here is a picture of the cable:


texts: Are there any contactless IR temperature sensors availbe for a range above 380C?

texts:
I need to measure the temperature of something without contact as part of an embedded electronics project (this sort of form factor would be ideal), and need a range up to 500C. There are IR guns (for cooking, baking etc.) on Amazon for up to 750C for reasonably cheap (>£50), but I can't find any sensors from the usual distributers (RS, Mouser, Farnell, DigiKey etc.) which go above 380C to integrate into an embedded electronics project. There are contact sensors for up to 500C, for very cheap (~£3) which is great, but I would expect to find some contactless ones too, especially since the technology obviously exists for the guns to work.

Does anyone know the technology that these guns use, and if they can be used in electronics projects?


texts: Can you identify these two SMD components?

texts:
A couple of components get knocked off by some loose elements during the shipping of some equipment. I'd like to identify the elements and solder in some replacement.

My guesses:

left one is a 270uF 16 V aluminium capacitor
right one is a 470 ohm resistor (or is it an inductor)

Please confirm or correct me.


texts: Decreasing the resistance in the input circuit of a transistor and its effect on the output current and voltage

texts:
With reference to this circuit:

Question: When the resistance \$R\$ is decreased, how does the lamp's brightness and the voltmeter's reading change?

My answer: The input resistance of a transistor circuit is given as \$r = (\frac{\Delta V_{BE}}{\Delta I_{B}})\$. So when R decreases, \$r\$ decreases, and hence \$\Delta I_B\$ increases (as they are inversely proportional from the equation). From the output characteristics, an increase in \$I_B\$ leads to an increase in \$I_C\$ and therefore the current in the lamp increases; leading to it getting brighter. As \$I_C\$ gets higher, voltage in the output circuit increases and the voltmeter has a higher reading as compared to its initial value.

Answer given:

Even though my notion that the brightness and the voltmeter increases is right, my reasoning is quite wrong. How does the circuit become "more forward biased" when \$R\$ is decreased? And why is it that \$I_B\$ decreases while \$I_C\$ increases. Why aren't both of them increasing? And if possible, could you say why my concepts are wrong?


texts: What is the name of this oscillator topology?

texts:
What is the name of the topology of the oscillator shown below?

I try to understand how it works and what are the design equations. But in order to find that, I first have to know the name of the things. (There is no schematics entry on google...)

Or maybe someone has time to thoughtfully explain the system...

EDIT:

I am convinced now: the load is part of the oscillator. I edited the schematics and included it.

I added a name to each net as suggested.

The source is a Youtube chain of French EE that does fancy stuff:
Four à induction : Incroyables Expériences [81]
The schematics can be seen at the very end of the video.

I have also simulated it on LtSpice. The slight imbalance between R1 and R2 start the oscillation. Equal resistors do not work (at least in simulation) but nothing is really equal in the real world...

This takes time to start (~10 ms) but it oscillates at 100Khz as expected (by the youtubers).


texts: Bidirectional control of two different actuators

texts:
I have two actuators, part of two different mechanisms:

A cheap brushed DC motor with gearbox coupled to 2 limit switches
A Firgelli L16 linear actuator with protective limit switches (not accessible)

And I want to control both of them with a 12V supply via a DPDT to change direction to limit the parts count.
I can see two problems:

I think the linear actuator is protected against supply cutoffs, but not the motor => inductive spikes
The limit switches have to be transparent to the linear actuator since it is on a different mechanism.

Will this work? Is there any simpler?
PXTY refers to the switch between pole X and trigger Y of the DPDT, LS is limit switch and CW/CCW are clockwise/counterclockwise.

simulate this circuit – Schematic created using CircuitLab

Note that the DPDT will have a center off position. Here is the "truth table" of the motor:

DPDT={T1} AND LSCW={open} (LSCCW don't care) => Motor OFF
DPDT={T1} AND LSCW={closed} (LSCCW don't care) => Motor ON CW
DPDT={T2} AND LSCCW={open} (LSCW don't care) => Motor OFF
DPDT={T2} AND LSCCW={closed} (LSCW don't care) => Motor ON CCW
DPDT={C} (LSCCW and LSCW don't care) => Motor OFF Linear actuator OFF
DPDT={T1} (LSCCW and LSCW don't care) => Linear actuator ON UP
DPDT={T2}(LSCCW and LSCW don't care) => Linear actuator ON DOWN


texts: How to prevent voltage spikes when motor is turned off

texts:
I have a schematics as shown below. The power source is a benchtop power supply which supplies a constant 24V power. Motor is controlled with ESC.

When running the motor and then turning it off I can see that voltage rises significantly (more than 35V). I understand that this should be because of the motor which is an inductive load. So when ESC switches motor off the magnetic field collapses which generates a temporary voltage across the inductive load which basically acts as a series connected battery.

How would I handle this so there is no voltage swing when motor turns off? Would a flyback diode over the power input rails help? Or should I add a clamping device like a TVS diode between the rails?


texts:
I like to build a device that needs long term time stability. In germany, one of the best simple clocks use the mains power frequency to obtain a time measure. While the frequency is allowed to change a little with the power net load, the errors are nullified over longer periods, usually over night. So in the long term, a mains driven clock is actually atomic clock driven and very precise.

This applies to the whole european power network I guess.

So I wonder how about other countrys worldwide? Would it be feasable to use mains frequency for timing issues after adjusting to a country's official frequency?


texts: What is the correct / better way to align two connectors across boards?

texts:
I have a 96 pole connector and a 32 pole connector on one board which plugs into the mating connectors on another board.

What is the correct way (and hopefully easier way) of ensuring that they are aligned ?

I've dealt with 1 connector in the past and if it was slightly off, it wasn't a big deal because I had space to shift the board so that it aligns. In this case, I can't because if I shift the board up or down, I'm shifting the alignment of two connectors.

What I do, is carefully take measurements and and hope that my measurements are correct.

But maybe there is another way, and maybe an easier way.

I have the following

Datasheet with measurements
3d step model of each connector
Altium
I also have access to Solidworks or Autocad (have to check to see which one) but I    never use it.

Can I use something from the list that would give me a better sense of security that it's correct rather than just me figuring out lengths ?


texts:
I want to check the power across a device in Proteus. But I am unable to understand how to connect Wattmeter pins to the circuit. Please Help me to understand this or suggest any other method to calculate power.
Thanks


texts:
I am designing a stripline filter with ADS and I am interested into the interdigital structure.
It seems that ADS only has SCLIN component for coupled edge structure, which is thought for parallel coupled type since the width parameter is common to both lines.
Interdigital type requires independent width setting for each line.
So how can I simulate interdigitsl structure using ADS?


texts: Equalizing unequal grounds with batteries

texts:
I know that it's usually perfectly possible to connect two grounds, and that voltage is measured against it's ground, but this got me wondering about batteries. I'm assuming somewhere in my train of thoughts I'm missing something, but I'm having difficulty figuring out where. So, let's go with an example of what I think should happen.

If I plug a battery (say my laptop) in at home, charge it and unplug, from what I get the ground of the battery remains at the level at which the ground in my house was.
I take my laptop to work, whole different city where the ground is probably at a different level from at home. I would guess that this difference would lay anywhere between -10 and 10 volt, but might be enough to fry a laptop. I don't really know.
I plug in my laptop. The moment I plug it in, the ground in my battery equalizes with the ground at the office. This means that a voltage of about 10V shortly gets short-circuited, and my laptop is busted.

I know this doesn't happen, so I clearly got something wrong, but what exactly? And if moving a battery from one ground to the other isn't a risk, then why is connecting two grounds ever a risk?


texts:
I'm trying to do a question that requires me to design an inverting op-amp in multisim and find the slew rates in different scenarios using the OPAMP_5T_VIRTUAL operational amplifier model found in the multisim component library, and view the output on the oscilloscope.

The input to the op-amp is from a signal generator :

Triangular wave amplitude: 500mV

Triangular wave frequency: 11 kHz

The op-amp should have a gain of 6.

Here is my circuit design from my understanding

the first part was to calculate the minimum slew rate, the virtual op amp values were not changed and the default slew rate is already set to 1M V/us.

so i simulated the circuit and the output was :

i placed the cursors in the linear region of the waveform in the oscilloscope to measure minimum slew rate : SR=∆2.395V/(∆36.290µs)=0.066 V/µs (is this value for minimum slew rate correct?)

In the next part of the question i have to simulate the circuit twice of the minimum slew rate and one fifth of the slew rate and the output waveforms should be on the same oscilliscope:

twice the minimum slew rate = 0.066 X 2 = 0.132

one fifth slew rate = 0.0132

To do this i set 2 circuits one circuit with slew rate of 0.132M and the other one with 0.0132, all other settings of the op amp are default and untouched.

So my circuit design now looks like this:

After running the simulation the output on the scope is:

The red wave(channel A) output is from the op-amp with slew rate of twice the minimum slew rate and the blue wave(channel B) output is from the opamp of one-fifth of the minimum slew rate. Is this simulation output correct?

also, what can i say to discuss the differences between simulation results that indicate slew rate distortion is taking place.

If anything is unclear and not understandable I apologize.
Thanks


texts:
Trying to wrap my head around the basic of how to do decimal addition in an ALU. Here is what I have so far.

I am primarily looking at the MOS 6502 CPU architecture. It has two modes in which you can do operations on values. The first is normal mode. Give it two hex number and you get a hex number. Example,

0x5 + 0x6 = 0xA

The second mode (decimal mode) will take two hex numbers (between 0-9) and output the result  in hex BUT adjusted so it looks like decimal. Example,

0x5 + 0x6 = 0x11

So I fell back to my python programming to write out a simple function to emulate the mode. Basically, every time your hex number is divisible 0xA(10) then you add 6 to the result.

def add(a, b):
    c = (a+b) + (((a+b)/10) * 6)
    return hex(c)

add(0b1111, 0b1111)
'0x30'

So,

How is this done using digital logic?


texts: White cable with a Black Stripe and tons of unknowns

texts:
Currently installing a replacement power supply for my old 24V LED Strip lights in the kitchen. Almost got it fully connected, but on the DC end I hit a snag:

I made a small error in my wiring reference, the picture of the cables running from the PSU to the LEDs is from an angle that does not tell me which of the white cables is the V+, and which is the V-. I only noticed this after I disconnected the old PSU from the connectors. The new PSU is NOT the unknown, it has clear labels.

So in short: What polarity does White cable with a Black Stripe running along its side usually indicate?

I referred to What do solid/striped lines on a wire indicate? but this in-question had black wire with white stripes.

I have a suspicion that it is Positive, due to white cable with yellow or red stripe being the positive, but I am unsure because its black stripe.

EDIT: Adding to the issue:

A potential Answer would always be use a "multimeter":
However how do you use a multimeter to distinguish is for an input cable? A multimeter doesn't really output power to power the strip.

Second problem is that the wires in the PCB do not seem to be the wires I am getting on the other side. So would the best course of action be disassemble half the kitchen to rewire everything?


texts: LED capable of either IR or visible light (not at the same time)

texts:
I'm looking for a type of LED (or some other small light emitter) with two modes:

IR light only
Visible light, if it also emits IR light here it doesn't really matter

Could something like an "RGB LED" be used to change spectrum outside of the visible?

Background stuff:

I want to use these in a costume at a convention with a fun twist. When people use cameras (can receive IR light) they will see things not visible in the real world. I want to be able to switch it into the visible spectrum at various points though. And as it will be used in clothing I don't have much space for two LEDs(IR + normal).

Thanks for your time


texts:
This is taken from an app-note on the ONSemi NCP1014. Pin 1 of the NCP1014 is Vcc, and I don't understand how it is powered in this configuration. The datasheet linked above mentioned a dynamic self supply powered by charging a cap on Vcc but I'm really not sure how that works given the polarity of D5. Is current drawn through C4/5 here, charging those and C7 on the Vcc, then C7 discharged to power the device?

The App note also mentioned that D6 is only there for a fail condition and when activated would blow F1.


texts:
First off I have no background in electronics but have been coding since decades and have successfully built things around an STM32 blue pill.

Now I am trying to build a battery powered circuit which should have a push button to turn it off. Once the circuit is off, another push of the same button should NOT turn it back on (turning it on it will be done by monitoring voltage of a separate circuit). I have found tons of latching circuits but all of them incorporate the turning back on feature which I explicitly do not want. Is there an easy way to do this (without using an MCU)?


texts: Encoding delay of Ethernet and the relation to cable frequency rating

texts:
I asked a question here called "Speed of electricity (signal propagation?) through copper for communications delay". I wanted to know how long does it take a signal to travel down a length of Cat5e cable (my background is telecomms and networking for this question).

In the opening paragraph on this Wikipedia page it states the following about Cat5 cable;

"The cable standard provides performance of up to 100 MHz"

In my previously referenced question I was pointed to a general rule of thumb for wave propagation which was between 4.9 ns/m and 5.3 ns/m. 100Mbps data transfer over Cat5 cable means 1 bit of data is encoded onto the wire every 1 second / 100,000,000 bits = 0.00000001 ns (that's 1 bit every 10 ns).

From this I assume that the receiving device will expect and receive and decode bits at a rate of 1 every 10 nanoseconds. If the delay down the coper wire (between 4.9 and 5.3) is less than the encoding delay though, surely bits will be being received too quickly at recipient end, faster than they can be decoded into a digital stream which could be buffered?

Also to tie this all together, I have assumed that cat5 is rated for 100 Mhz because that means in each cycle 1 bit of data is encoded onto the wire. Or does this 100 Mhz represent something else? Cat6 is used for gigabit transfer rates (or cat5e) with a frequency of 250 Mhz. Presumably this is just because fancy encoding methods are used to encode more bits into a single symbol on the wire. So, the 100 Mhz reference above from the wiki article is the reason it is a one to one ratio for encoding data onto the wire so we end up with a 10 ns encoding duration per bit. Is that correct also?


texts:
I want to prevent ESD and I read that connecting the wrist band to i.e. USB ground is not a good idea. My oscilloscope has a test output where I would like to connect the aligator clamp of the ESD wrist band to ground. Will this harm the scope?
How about the measurements with the scope? I would start measuring only after connecting the wrist band. I assume that I charge myself only slowly so there should be no spikes after connecting that could affect the measurements. Is that right?


texts: How to fade or delay a DC Signal to remove speaker "thump"/"click"/"pop" from transistor switch?

texts:
I'm trying to create a digital audio switch or relay using an Arduino nano.

It's a very simple circuit, it's just a gate (transistor) which is operated by a digital signal (computer) through a microprocessor (Arduino nano).

I have a NPN transistor working as a switch, which receives the audio signal (at the collector) and receives a 5v signal from the Arduino (at the base) to open the gate and then send (at the emitter) the audio signal to the speaker. It works fine, except for the noise ("click" or "pop") that is heard when the gate opens. I did some research and it seems that a capacitor could open the gate slowly (fading in) eliminating the noise.

I've tried some types of ceramic capacitors and I'm not sure if I'm doing something wrong or using the wrong capacitor, but so far I had no results.

I guess it would be just like fading in a LED from a 5V signal passing through a transistor. Could anyone help me?

Thanks a lot!

Ian

Below is an attempt of a schematic, my apologises if it's not very accurate (I'm a musician).

simulate this circuit – Schematic created using CircuitLab


texts: Is the ATtiny85 actually used in any consumer electronics?

texts: I was wondering if anyone here knows of any products that utilize the ATtiny85. It appears to me that it's solely used by makers/electronics enthusiasts. I'm asking because I think it would be interesting to see to what products its limited IO and storage can be applied. Sorry if this is the wrong place to ask a question like this - I couldn't find a more applicable SE site.


texts: Switching power source using P-channel MOSFET

texts:
In a below schematic, PVBUS and VBUSIN are both attached to USB VBUS of two different USB ports (so +5V). The goal is to be able to power +3V3 regardless of whether VBUSIN is present or not. If VBUSIN is +5V PVBUS is unconn, the IC (SPX3819) is powered by VBUSIN, the other way around (VBUSIN - unconn, PVBUS - +5V) by PVBUS, when both are +5V then powered by PVBUS.

Does this schematic implement this logic? Do I need to add a resistor (100k?) between PVBUS and VBUSIN?

If this does not work, then how could this logic be implemented without incurring voltage loss? (any IC that provides this logic already?)

OR is the 2 separate VBUS connected in parallel not a concern at all and there is no need for such switching?


texts: Behavior of logic gates when one input is undefined?

texts:
I tried to understand to behavior of this circuit when it has no voltage supply at first which means the current state is neither 0 or 1. You can say that there is a 'nothing' input. Then when the switch on digital pulse go to the input but there is a 2-input AND gate but there is only 1 known input because there's no signal at first so I don't know how it would behave this time as the outputs of A, B, and y are neither 0 or 1 so I can't use the truth table or state equation which is a function of the input and present state. There is no present state here to begin with.

If I follow the truth table, then A=0, B=0, x=0 result in A=0, B=1, y=0 in next stage. However, when there is no voltage supply at first. A is not equal 0 because if A equal zero then A'=1 which require voltage supply but there is no voltage supply to make it so


texts: How to use the same switch to control LED and vary resistance?

texts:
I am struck with a simple board design problem.

The requirements are : I have a 4 position slide switch according to the position of the slide switch, I should turn on different colored LEDs and also vary the output frequency of 555 timer in astable mode and drive a piezo buzzer.

I plan to vary the output frequency by varying the resistor values connected to 555 timer.

Problem : I cant use the same switch to control LEDs and vary the resistor values. How to achieve this that is changing the switch position should select different LEDs and also vary the resistance, thus varying the frequency of 555 timer.


texts: Turning a 10A 24V signal on/off with a 5V signal

texts:
I'm currently working on an electrical power steering (EPS) system for an electric vehicle. The motor, which will assist the driver, is this stepper motor. The motor will be controlled by this stepper driver.
The stepper driver will be powered by a 24V line, and outputs a maximum of 10A. For safety reasons (in case of any errors in the system) I would like to able to cut the power to the driver, thus turning the system off.

The solutions seems to be either a transistor or a relay, however I've ran into some issues regarding both approaches.

For a transistor I'm a bit concerned about the dissipated power, both in terms of heat (though I imagine this can be fixed with a heatsink), but also in terms of power that simply goes to waste. As mentioned the vehicle is electric, and as such the EPS-system will be powered from the car's battery. The vehicle is a fairly small racecar with limited battery capacity (I don't have the accept number at this time), and I would very much prefer if I could keep any unnecessary power consumption at a minimum.

A relay seems to be a more power friendly solution, however I am uncertain if they can deliver the current I need. Take for example this relay, which can deliver 10A 28VDC to a resistive load, but only 5A 28VDC to an inductive load. The relay would be directly connected to the motor driver, however since the driver is connected to the stepper motor, is it then correct to assume that the motor is the real load, and thus the relay is connected to an inductive load? In that case this relay wouldn't work. I've found other relays that can deliver the desired current, but they require more than 5V to trigger, which is not an option, since the logic signal which turns it on or off is only 5V.

It's very possible there is a third option that I have not even considered.

In advance I would like to first apologize if this is not the correct site for such a question, but also to thank anyone who can provide some insight.


texts: I have a PCB that I'm sending off for assembly, which includes going through a reflow oven.  The last batch had a problem because the solder mask on some PCBs does not completely insulate a via that is underneath a metal connector, resulting in a short.  What can I safely use (that will withstand reflow temperatures) to paint or insulate the via to prevent the short?


texts: Why is information not doubled in this context?

texts:
Regarding the following section from a text:

Why is information not doubled but increased 4/3 times? Can you give an example to clarify what is meant here?

What is meant by information here?


texts: Heatsink land pattern interpretation (DPAK heatsink)

texts: I'm looking at using a D Series heatsink from Ohmite. The land patterns on the last page of the product PDF are very lightly labeled and I'm not entirely sure how to interpret them https://www.ohmite.com/assets/docs/sink_d.pdf?r=false. From what I've seen elsewhere I think the first rectangle is the actual copper area under the back pad of the device and the second trio of rectangles are the solder mask openings.  I think the dashed outline rectangles under both of those are supposed to be the pads for the leads but they don't seem to be spaced right, at least not on the first diagram.


texts: How does a Watt (1mW from a laser) relate to Amps (20mA max current rating for collector of a phototransistor)?

texts:
How does a Watt (1mW from a lasermodule) relate to Amps (20mA max current rating for collector of a phototransistor) ?

I want to know if the 1mW output from the laser is within or outside the range of what the phototransistor can deal with (20mA max)
Laser is powered of a 5V circuit.


texts: I use OrCAD environment for designing PCBs but I've never thought about what is the purpose of a Drill Symbol in padstack creator.  The diameter is set in the Drill bookmark and other parameters like antipads or thermal pads in Design Layers. I can see it in the layout file. What is that used for?


texts: Why would you connect AC ground to an isolated DC power supply output?

texts:
I have been working on this question for a while now.  I have read, and learned a lot, about power supplies, ac power, and safety.  But one thing I just cannot seem to understand is why one would connect the AC ground (or protective earth, or functional ground, I believe they are all the same) to the DC output + or -? Wouldn't that forfeit the protection that isolation provides?

I am sorry if this is an obvious thing, but I have been really searching for an answer, but I am seeing all kinds of conflicting answers.


texts: Question about a dimension in this IC package drawing

texts:
this is the first time I'm making a PCB layout, so I'm not too familiar with datasheets. The picture below shows a diagram for an IC I'm using. The datasheet says all dimensions are in mm.  However, near the bottom you can see a number that has 0.25 with a circled M, followed by an A and C. What do these letters mean? And does that mean the hole size is 0.25 mm for a pin? I'm really confused because I know it can't be 0.25mm.
Is that in mils instead?


texts: simple matlab function (simulink) with if?

texts:
have written the very basic Matlab function on Simulink and would like why I am getting this error:

function [pos, neg] = select_output(err)
% if the error is negative , flow through the PID designed for negativ
% errors otehrwise positiv
if err >= 0
  pos=err;
else
  neg=err;
end


texts: Which shake sensor has the highest “movement” sensitivity?

texts:
I bought some shake sensors (switches), the SW-18010P and the SW-18020P to use in a project that would make a device leave its stand-by state when it’s moved from a stationary position (over the table)

But when testing (both of them) connected to an Arduino, they don’t behave the way I wanted. They can’t “sense” the device being lifted slowly from over the table, or moved in my hand when walking.

They do work if I shake it with a lot of force.

I wanted something more sensitive, gentle, that could detect the slightest movement, from laying still over the table to being lifted or moved around, without any shake or jerkiness.

Is there any simple shake sensor that is that sensitive, even to a gentle tilt?

I tried connecting the sensors either in an analog pin (one leg on Arduino 5V and the other on the analog input) and also one leg in a digital pin with pullup enabled and the other leg in ground.

Both gave me the same results.

My device is a dual slave flash with a common battery-power source. When it´s laying flat on the table, I´d like it to enter stand-by mode. If I get it to use it, I´d like it to automatically leave stand-by state. The controller (and battery case) is really small, and I lack internal space to fit more stuff than I already have... A shake sensor is really small, that´s why I preferred this route, rather than using an accelerometer.

Cost isn´t a huge deal as it´s only one unit, but internal space in my enclosure is. That´s the main reason I tried this kind of small sensor.

Here is the original datasheet (in Chinese). I translated it but I can´t find an option to upload a PDF from my computer, only images. I´m trying to convert the translated text to JPG.


texts: basic arduino question - do I need a 555 timer?

texts:
I have an Arduino (duemilanove) connected to a floppy disk drive and I can happily control the stepper motor using three pins on the ribbon cable to three digital pins of my Arduino (well 2 + the ground!).

I would like to control multiple motors at once, but using one Arduino per motor is going to be costly. I have read a bit about 555 timers. If I wanted to control two motors simultaneously stepping the motors independently of each other from my single Arduino, could this be done with a 555 timer IC for each motor?

The Arduino is "single threaded" so I want a way, I guess, to push the "commands" (signals) for driving the step motors onto another chip. This way the single thread of the Arduino can loop round each chip handing out commands for their attached motor (or maybe a method of queueing?).

I have read a little about interrupts on the Arduino also, but I don't think these will be any use will they?


texts: What equation do you use to find these current?

texts:
Components: 9 V battery (actual voltage is around 7 V). No resistor is used. Only red LEDs connected to a battery.
There are 2, 3, and 4 LEDs connected in these circuits with current readings. I can see that with 2 LEDs, I get 14.28 mA. With 3 LEDs, I get 3.19 mA, and with 4 LEDs I get 4.7 mA.
In real life, I know the answers to the current of these 3 circuits. But if I didn't have a multimeter, how would I calculate to find the current?
I'm aware of Ohm's law but I can't find an example that doesn't include a resistor, which is my case.
I'm a total beginner, so I appreciate any advice. Thanks!


texts: How does an Active RFID transponder tag get activated?

texts:
From what I can find on the Internet about active RFID systems, it seems the reader sends out a signal at a certain frequency and if a transponder tag that operates at the same frequency is within range, it will activate and send its signal back to the reader. Quoting from the site I found this:

  In a system that uses an active transponder tag, the reader (like passive systems) will send a signal first, and then the active transponder will send a signal back with the relevant information. (Source)

I understand this concept at a very basic level but I am wondering why transponders that operate at 2.4GHz are not activated by being within range of a wireless router? If they respond to RF waves at that frequency wouldn't they be activated and send out a signal, albeit one that would just get ignored?

I have no background in this and am just starting to learn about RFID so if anything I said is fundamentally flawed or unclear I apologize.


texts:
I understand how/why graded absorbers work - you achieve a match with free space by gradually varying the electromagnetic properties from "almost air" to strong absorption (either geometrically like pyramidal absorbers or through density like graded foam sheets).
How does this work for those (very thin compared to e.g. pyramidal absorbers) absorber sheets? How come they actually absorb energy and don't just reflect most of the waves due to this very sharp step?


texts: Recommendations for building a dedicated external speaker from an older computer

texts:
I'm super excited to jump in and learn more about building an external stereo speaker from an older salvaged macbook laptop. I loved using the laptop to reference how my music sounded to get a better understanding of the playback for people using their laptops to listen to music. Anyway, this laptop has finally died and I would love to repurpose the speakers within (maybe also the class d amplifiers?) and just plug an auxiliary cord and listen. I think this is a fun project yet I'm hitting walls with my understanding of circuits and reading schematics.
I envision removing the left and right speakers from the logic board as well as what powers and drives those speakers (which I believe is the class d amplifiers)
I have found a schematic of these audio circuits and envision creating a circuit board containing these components. I also envision adding a 3.5mm aux input and volume knob to this circuit to input sound and control the volume.
I feel that with the directions of the schematic, adding a volume knob and a 3.5 mm aux input isn't too crazy of an undertaking. Is there anything I am missing?
Is this doable in your opinion? Also any thoughts or recommendations for this project? I feel like the learning curve on this project is extreme but I'm super excited to learn and welcome all feedback and suggestions! Thank you in advance.


texts: Is there significance to length in a matched transmission line?

texts:
I am looking to dabble into some RF PCB design with a microstrip line to a WiFi chip antenna, and I am trying to understand if my intuition is correct.

I have used various calculators to determine the width of the trace I need for a 50\$\Omega\$ \$Z_0\$ on a 4 layer PCB -- all agree with roughly 18 mils on FR4.

Since the transmitter, transmission line, and chip antenna are all 50\$\Omega\$, there should be no standing wave pattern along the line and \$V(x)\$ and \$I(x)\$ (where \$x\$ is the position on the line) should be constant.

Aside from ohmic losses and parasitics (which the latter can be tuned out), does this imply that the length of the line can be arbitrary? i.e.,  the trace does not need to be a specific electrical length such as \$\lambda/4\$?

I am leaning towards that it isn't, but I've reviewed some reference designs from TI (the CC3100BOOST and the CC3200 Launchpad) that have caused some confusion. The CC3100 uses a trace length of 660mil from chip to antenna, which is almost exactly \$\lambda/4\$ at 2.4GHz, and the CC3200 uses a 1200 mil line, which is very close to \$\lambda/2\$. I'm not sure if this is intentional or a coincidence.

I'm looking for a (perhaps tediously) clear answer before I make any mistakes.


texts: What is the voltage at the inverting input terminal of an op-amp, with respect to ground?

texts:
I am currently writing a lab report for an introductory lab in electrical engineering on the subject of op-amps. One question that I'm stuck at is

  With the op-amp operating in its linear regime, what voltage would you expect at
  the negative (inverting) input terminal, with respect to ground? How does this
  compare with your measurement of \$V_n\$?

I think the goal is to test the idealness of an inverting op-amp with the data that I have here:

The op-amp circuit:

simulate this circuit – Schematic created using CircuitLab

Supply voltages:
\$V_{cc+}=15.664\$ V
\$V_{cc-}=-15.143\$ V

I was taught that the golden rule of an ideal inverting op-amp is \$V_n=V_p\$. But what is \$V_p\$? It can't be the input voltage because of the golden rule. How do I answer those questions with the given data?


texts: Suggest a Rail-to-Rail OpAmp to Replace LM741

texts:
I have built a small amplifier circuit around two LM741 op-amps and have had to learn the hard way, as I usually do :), that the LM741 is not a rail-to-rail output op amp.

I have a 0-3.26V input which is to output -10V to +10V, and the circuit is being supplied by +/- 10V so I am not getting near the output needed.

Would someone be able to suggest a rail-to-rail dual-power (I'm assuming as I have +/- 10V output) that can easily replace the LM741.

By easily replace I mean pop one out and pop another in :), same connection diagram. Thanks a million for any help.


texts: I'm trying to boost 12v to 19v(for charging laptop) with a cheap boost converter. But I noticed that I have some voltage ripple (See images). What can I do about this? And will it hurt my laptop charging circuit.


texts: UART works when I open minicom before starting UART

texts:
I am trying to send out large amounts of data at 115200 via UART. I have come across a rather strange problem. I am sending out data in the while loop of the MCU. The MCU is not doing anything else. I am bitbanging UART via a IO pin. I observe that if I open up minicom and then start UART the data is observed correctly. However if I start UART and then open up minicom I dont get the right data. I suspect this has something to do with stop and start bit detection. Since when I randomly open up minicom it takes the stop bit and start bit to be one of the data bits and the data is not correct. This is because the data is being sent out all the time. Does this sound like a reasonable explanation? Or is there something else?

Traces:
http://wikisend.com/download/389684/notworking.csv
http://wikisend.com/download/977160/working.csv

This one is the working


texts: Why is it so problematic to have close to zero standby power consumption?

texts:
Each electronic device consumes electric power when it is "idle" unless it has a mechanical switch. I can understand that for example a TV with a remote control needs to "be ready" to receive a command from the remote control. But even a cell phone charger consumes power when it is connected to the outlet and not connected to the phone.

For example, Nokia claims that one of its new chargers consume less that 30 milliwatts when not connected to the phone and they say it is very cool. I don't understand - the charger is a very simple device, what does it do with those 30 milliwatts?

Why can't this standby consumption me made lower when we already have microprocessors with gazillions of transistors fitting onto a plate size of fingernail? What's the fundamental problem here?


texts: Placing an ultrasonic sensor in a corrosive environment

texts:
A year or so ago I built a simple gauge for the fuel oil tank in my basement using a MaxSonar-EZ ultrasonic distance sensor. At some point, it stopped working, and when I removed it from the tank today, I found that there's quite a bit of black … uh, "stuff" on portions of the PCB, wires, and pads. I'm assuming it's corrosion of some kind.  Although it's not outside of the realm of possibility, I don't believe the sensor got splashed and I know it wasn't submerged. I don't know if the transducer is itself damaged. I never liked that sensor much, so I've got a Parallax one that I intend to put in it's place. I'd like to find a way to make this sensor more resistant to the environment (assuming it's the environment that's caused the MaxSonar unit to die), or find a better replacement. I'm fairly confident that I can protect the Parallax sensor's PCB from the air in the tank with some acrylic sheet and Permatex gasket maker, but the transducers will necessarily be exposed. I'm not sure this is sufficient, however. I'd appreciate other suggestions on how to make a more durable gauge!

Thanks,
Brian


texts: How does a small active region contribute to good lasers?

texts:
In my class notes, it says that heterostructure LEDs have better lasing capabilities than homostructure LEDS because "of the confinement of electron-hole recombination within a highly restrictive active region". Why is having a confined active region contribute to having good lasing capability?

According to Wikipedia, this has something to do with the fact that the junction is like a quantum well, but I'm not clear on what that means.


texts: How do I distribute heat from a heating pad to my electronics?

texts:
I'm building an outdoor sensor system (a bunch of sensors and a Raspberry Pi inside a plastic enclosure). A few weeks ago, one of my prototypes got too cold (ambient temperature went below 0deg Celsius). While the sensors can handle sub-zero temperatures for a short time, it does reduce their lifespan, so I want to heat the components up slightly.

I bought a heating pad and have got it working (using one of these as a controller). However, it seems to keep all of its heat within the pad, rather than heating up the air around it. For instance, if I put my hand near the pad (2-3cm above it), I don't feel any heat, but if I touch the pad, it is very hot. My thermometer showed it reached above 50deg Celsius, so I know it's working.

How do I go about distributing this heat towards specific components within my enclosure?

Should I just stick a big heat sink onto it, and then have a fan pointing at the heat sink and facing in the direction of where I want the heat to go? Or is there some more efficient method?

Thanks.


texts: Why does a thermocouple circuit need to have minimal current flowing through it?

texts:
I was reading on this website that

  it is imperative that current in a thermocouple circuit be kept as low as possible for good measurement accuracy

Why is this the case?

Also, if one makes it so there is very little resistance through the thermocouple circuit (and hence less voltage drop inaccuracies), then wouldn't this cause the current flowing through the circuit to be high by nature?


texts:
In Ethernet module , why do we need FIFO block before the mac layer ? Can we bypass it ?
Thanx in advance


texts: Effects of magnetic field on conductor windings

texts:
I'd like to know if there is any effect inside a conductor while it's resting in a magnetic field.
More precisely with the HAL effect, which can only be measured across (perpendicular) to the conductor, is there an effect (change in inductance/capacitance/resistance/frequency response) which could be measured along the conductor (from both ends of the wire), which gets influenced by the HAL effect.


texts: Loud sound and crystal clock,how big problem it is?

texts:
I want to use piezo crystal clock in place where loud sounds exist,I worry that it might decrease the performance of the clock,create spurious tones for example.

The db level at the clock will be around 100 db,or 2 pascal pressure.Clock will be typical small clock,it will not have two or three layers of metal around it like some of the big expensive oven clocks.

I think damage is unlikely becose manufacturers often test the clocks for g-force and there is no way sound of that amplitude is going to shake them beyond those specifications,but some kind if clock signal degradation seems quite possible.

The question is,is sound at those not too high levels ( 100db ) problem? Does it create some degree of clock signal degradation for your typical small piezo clock? Do you have any experience,or did you ever heard or read about sound affecting piezo crystal oscillators? Is this common problem or are crystal clock relatively immune to interference from sound?


texts:
I would like to connect a headset to my radio (Cobra AM845.)
The Cobra radio has a 2,5mm audio jack and the headset has a 3,5mm audio jack. I made a PCB to connect the together as:

When I close solder jumper 1 and 2, I can hear the voice in the speakers.
When I press the pushbutton SW1, I can hear on the other side that there is something recognized, but I don't hear any voice.
How do I have to connect the ḿicrophone to hear the voice?
In this image the microphone gets shorten when the button is pressed. How should it work or is this button a normal closed button and opens when pressing?
https://pinouts.ru/images/treo600stereo.gif


texts: Why can a (industrial) servo motor run faster with higher DC-link voltage

texts:
why can a servo motor run faster with higher voltage? While I was searching for a servo and looking through the catalogs of different manufacturers this question popped up. Like you have a inverter which is generating the voltage for the motor. But the current basically gives you the torque. So with a higher current you could produce more torque. But for the speed, it depends which frequency the inverter delivers to the phases of the machine. At least this is my understanding of how it works.

To give you an example of what I mean: In this document you find a bunch of motos: https://www.kollmorgen.com/en-us/products/motors/servo/literature/akm2g-selection-guide/

They all have different rated values for different voltages (different inverters) and I'm wondering how this relates with the speed of the machine.


texts:
I need low power wifi for a not-very-data-intensive application.  What modules or chipsets should I look at?  Other than low cost and low power, I have no restrictions.  The cheaper the better.

This is for a high volume product, so both hobby level (since I can trace it back to an oem module) and oem level suggestions are welcome.


texts: Solid-state AC load switching for both line and neutral wires

texts:
The common TRIAC circuits for switching AC loads cut only one wire (line).
I need to cut both (line and neutral). Is there a configuration to achieve this?
Even most encapsulated solid-state relays cut only one wire.


texts: Do any devices support handshaking on SPI-ish bus without extra wires

texts:
The 4-wire SPI bus has a considerable speed advantage over I²C, but unfortunately so far as I know has no standard way to perform handshaking without using extra wires beyond the four (and four wires is already annoying enough as it is).

For a recent project where the slave was a CPLD, I implemented a nice approach to provide handshaking in one direction (slave can make master wait) and also incidentally eliminate the need for the /FS line.  The signals are Clock, MOSI (master-out/slave-in) and MISO (master-in slave-out).

Clock idles low; both MISO and MOSI output on the rising edge of Clock and are sampled on the falling edge. Two or more consecutive rising edges on MOSI wire while Clock is low will reset communication.

When Clock is low and MOSI is high, MISO will indicate whether the slave is ready.  When clock and MOSI are both low, MISO will indicate whether the slave wants attention.

While this approach works very nicely when communicating between my CPLD and my controller, it would be nice if the same approach could be used when communicating between two standard microcontrollers.  The biggest features that would be necessary to make this work nicely would be:

the ability of the slave controller
to reset itself upon receiving some
number (probably 2 or 3) of rising
edges on MOSI while clock is idle;
the ability of the slave to control
the clock-idle state of MISO, and
preferably load separate values for
use when MOSI is high or when it is
low;
preferably, the ability for the
master to control the state of MOSI
that will be output when the clock
is idle between bytes (in my
protocol, the commands which need
handshaking have the LSB set, but
that's a bit of a nuisance);
for buffered SPI ports, the ability
for the master to wait on the
slave's data line.

Do any common controllers or slave devices offer such features, or work in such a way?


texts:
I am working on a project in which we are trying to design and build an ultrasonic thickness gauge that will calculate the thickness of a given part based on the time difference between sending a signal and receiving a reflection back (using the known speed of sound through the medium). We are currently using an Arduino nano as the MCU for our prototype. We have successfully amplified the pulse generated by the MCU to a higher voltage, which is then used to excite the ultrasonic transducer (which is in contact with the part that is being measured). The reflection is then detected by the second element of the transducer and converted into an electric signal that is centred around the natural frequency of the transducer (5MHz). This signal is then processed (amplified and filtered) into a level that will be detectable by the MCU (circuit and scope screenshot as shown below). However due to MCU's limited sampling rate, the signal will not be reliably detected. Therefore I was wondering if we would be able to devise an envelope detector that would extract the amplitude modulation of the reflection signal, effectively converting a very high frequency into a lower frequency signal, which I am hoping will be detected by the MCU.

According to what I have read so far, this would be achieved by first rectifying the signal using a “super-diode” (precision rectifier configuration as shown below) and then integrate it through an op-amp integrator. However, it seems that because I am relying on single supply and the frequency of the signal of interest is very high, the rectifier will not work as I expected (op-amp used is LM7171, with very high slew rate 4100V/µs), in fact this particular design has proven useless with single supply, even though the very same op-amp has worked perfectly under a single supply arrangement for the circuits shown above. Is there perhaps a way of designing an envelope detector entirely from transistors instead of op-amps?

Any pointers or suggestions will be highly appreciated!

Thanks in advance


texts: In an ATX power supply, how is the -12V supply made?

texts: I was looking at a pin out for a 20 pin ATX power supply and noticed a -12V pin. I am now wondering; is this just a ground? If not, how does the PSU make a -12V supply rail?


texts: Why does a voltage buffer has an high input impedance?

texts:
When considering great voltage gains in amplifiers, a high input impedance is the main rule, followed by a low output impedance. But then, if we look at common-collector circuit (BJT), it has no voltage gain, and still, it has the highest input impedance.

I understand the calculations that get us to the input and output impedances, what I don't get, is how does this respect the ideal voltage gain amplifiers principles?


texts: When it comes in Digital Logic Design using IC (Integrated-Circuit) what is the term HANG Input means? what does it do? and how will it affect the output of the IC?


texts: Electrical gremlins under high Amp draws

texts:
I'm new here so I hope all goes well!

I have used an ATX PSU to create a power bench tester for testing automotive headlights. HID in particular which draw around 8-10amps on startup. I have noticed that whenever I start the bench with such a draw, the USB ports on my PC, connected to the same wall socket, disconnect and reconnect immediately. When tested with a standard 55W halogen bulb, the problem doesn't occur.

I don't recall doing that before therefore what could've gone wrong in my circuit to cause perhaps a jump in amps or what can I do to prevent troubles to my PC's USB devices?

I have used a 12V wire connected to a binding post by squishing the wire between the two nuts - afterward a binding connector which is crimped to a wire which has a female connector to which the HID bulb connects to. I have jumped the green/ground wires in order to start the PSU.

Everything is properly insulated with electrical tape.


texts:
I am really confused with the above problem. I can also solve the problem taking an AC supply across a 20ohm resistor and end up getting like
P = 100^2/20 = 500W
I am not able to digest the solution provided to me by my coaching institute and think that my solution is correct. Please help me with the above problem.


texts: Trying to find the ratio of voltmeters V1/V2

texts:
I'm trying to find the ratio of voltmeters V1/V2. My attempt is shown below

Let's recall each resistors R and then we'll have V1 = (2R)(I) (since two resistors are in parallel). V2 = (3R/2)I (two resistors are in parallel and in series with remaining resistor)

Hence, we get the ratio 3/4. However, I believe that I've gone wrong somewhere. Could you assist me with that?

Regards


texts: Relation for the current generated by a photo-diode in photo-conductive mode

texts:
If a photodiode with responsivity R is operated in photo-conductive mode with
reverse bias voltage Vb and load resistance Rld what relation gives the output current from the photo-diode flowing trough Rld?

I know that generated current from the incoming optical power P is
Io = R*P, but I am not sure how is Io affected by Vb and Rl and when could reverse saturation current be neglected.

I am using this photo-diode BPW 34 FS with incident power levels of about 10 - 1000 w/m^2.


texts:
Desperately trying to find a receptacle to match these 10-years-old cords which come from a Beckman Coulter FC500 cytometer. Anyone know the name?

The receptacle previously used is labelled "AMP" with a squiggly M.

Requested infos:
Diameter of connector barrel at the end is 4.2mm/.165". Length of gold cap portion is 15.5mm/.610"

The connector seems to be push insertion, with a cheap friction-lock style retention clip on the receptacle (easily bent).

I've included the bag labelled "FOA" but it's electrical, not fiber optic! Could just be a reused bag...


texts:
I'm new to electronics and trying to make an astable multivibrator oscillator. The PSpice simulation doesn't work (it says netlist error when I place a mosfet or a diode) and I get a really low efficiency (like around 10% on falstad.com). Is there anyway I can improve the design?

Thanks


texts: How does one estimate the electrical power of a power plant?

texts:
I've asked several people how a power plant creates power (i.e. currents and voltages) and I found that they were unsure. In addition, I’ve done several searches to get more information, and I was not able to find links to answer my questions. I am very familiar with ac power relationships and all the mathematics behind it.

When a power plant creates power like the Hoover Dam, it can provide 2.07 GW of electrical power. My question is what does this mean? I assume from Faraday’s law that the induced voltage across the generator coil produces an current, and this combination (P = VI) is the actual power but I'm sure that my thinking is naïve. Can someone roughly sketch out how the electrical power of a power plant is computed?
If possible, what kind of voltages and currents are power plants producing before the Step Up transformers? Of course, this varies from one power plant to another.


texts:
I going to build for my scooter 24v 9.3ah battery pack,
I already order 21 pic' of 3.7v 3100mh 18650 Panasonic lithium battery I'm planning to conect them 3S3P,
Each battery rate of charging is 0.7C.

I would like to know what is the maximum current (AH) that I can charge my Pack with 24v lithium charger?

Thank you,


texts: Can I connect multiple speaker boxes to a single amplifier output?

texts:
I've seen arrays of passive speaker boxes (high output passive professional PA speakers) that were connected to each other and only the last (or first) one was connected to the power amplifier (a very high power amplifier in that case). The speaker cabiners had the sockets labelled IN and OUT, which means they had been designed for this sort of connection.

The question: I wonder whether the same setup - multiple speakers hooked on single amp output - is possible with standard consumer home audio systems (as my Cantons dont't have the OUT connectors). I'm only interested in the technical aspects, not in how the fidelity may degrade (I only use coat hangers to connect my speakers).

I'm not very well educated in this field, so I'd like to provide some of reasoning I'd already done, in case there is something to correct in there, too. I understand that one should never connect a speaker box of impedance lower than that for which the amplifier is designed (so you can connect 8 Ohm speaker to 4 Ohm rated amp but not the other way around). I'd count that impedance behaves quite like resistance in that, that if I connect the speakers in parallel, I'd end up with half total impedance and would need a 4 Ohm rated amp for a pair of 8 Ohm rated speakers. With three of them, I'd be down to 2,5 Ohm rated amp for 8 Ohm speaker boxes. With speakers connected in series, I'd need an amp power rated roughly equal to the speaker power ratings combined but won't need to worry about the impedance (as long as the speakers are same or higher impedance than amp rating). For simplicity, I use sets of same speakers (make, model, power rating, impedance) here because that is what interests me. My amps are D-class.


texts: Simple power supply circuit loses voltage over time

texts:
I have a simple circuit that I built from a 120V to 18V transformer, a bridge rectifier and a few passives. I have a voltage divider because my little $20 oscilloscope can only handle max 12V. I expect to see around 1.1 Vout, and sure enough I do. But then I went to the bathroom and when I came back the multimeter read 0.8V. So then I let it sit for a while, and the value keeps going down. If I unplug it and plug it back in, I start at 1.1V again. The transformer (which I salvaged from a broken UPS) gets warm, but doesn't seem to be alarmingly hot or anything. So I'm stumped.

My guess is that it has something to do with the RC portion of the circuit, relatively high resistance in the divider interacting with the cap somehow that I don't get, but I'm not finding anything online about it. Searching doesn't give me what I want because results for step-down transformers seem to get in the way.

Am I doing something dangerously wrong? Will I accidentally burn down my apartment?


texts: Control AC Sync. Motor by Blocking AC Cycles

texts:
I have an AC synchronous centrifugal water pump that I would like to control the speed of.  The main goal is to slowly start the pump and ramp up to full speed over about 60 seconds.  I believe this can usually be accomplished by a Variable Frequency Drive device but those usually do a lot more and cost too much to make this worthwhile.

Instead of converting the wall AC power to DC and then back to AC at various frequencies I was wondering if it would be possible to simple remove certain cycles from the 60hz AC power to get a lower frequency.  For example if I wanted to start the pump at quarter speed I would remove 3 out of every 4 AC cycles.  This would result in 15hz although it would also result in a pause between each hertz.  This kind of solution would be fairly easy to make with an Arduino and a dimmer board but I was wondering if anyone has any feedback on this.  Would this even work or would an AC synchronous motor not like the pauses between the cycles?


texts:
I tried to make a NOT gate with N type mosfet and everything seemed good when the gate had voltage, however I found strange things when the gate was open and that I put test components between the source and drain.
My voltmeter indicates a voltage of 1.8V between drain-ground, but a voltage of 1.6V between drain-source, even if nothing is going on at the gate. Then, I expected to have the remaining 0.2V at the 1M test resistor and/or parallel led I put between source-ground, but both were indicating 0V.
What am I missing ?
This mosfet's order is: gate, drain, source.

simulate this circuit – Schematic created using CircuitLab


texts:
What is the purpose of the C2 capacitor in the feedback loop?

What is the time-constant of the R4/R5/R6/C2 net?

This is for a pH-probe.

Source


texts: How can we persist the leds blinking rather than swithching from one led to other while using a demultiplexer

texts: Demultiplexers are used for many outputs. In the case of led blinking, but its difficult to identify the leds that blinked. Since its output get switched between many leds. How can I digitally switch between many LEDS but have the output persist? Without switching between leds using a demultiplexer?


texts: Change in resonant frequency of quartz crystal with atmospheric pressure?

texts:
We have a bare quartz crystal and we are measuring its resonance frequency to a very high accuracy (1 ppb). As it cycles between atmospheric pressure and vacuum there appears to be a change in frequency. Could this be because the crystal is being compressed? How can I calculate change in frequency if this is so?

Unexpected change, in temperature controlled environment, is about 400 ppb


texts: Finding the primary VA when winding your own power transformer?

texts:
I have been researching how to build power transformers but I am stuck on finding the proper wire gauge for winding the primary. In order to find the correct wire size I have to know the current in the primary coil. I have two different formulas from different sources for this that say different things.

METHOD 1
The first is an article written back in 1947.  Which says "the primary circuit VA is 1.4 times the total secondary VA.

METHOD 2 the other formula is from a transformer calculator which is Vp x Ip = Vs x Is.
Then divide primary VA / Vp (115)

My example problem is this

Vp (primary voltage) = 115
Ip (primary current) = ???
Vs (secondary voltage) = 19.2 volts
Is (secondary current) = 1.5 amps

When using Method 1 we get Ip = 0.35 amps. This seems to makes sense because the primary should be more current than the secondary to make up for any losses.

When using Method 2 we get Ip = 0.25 amps. This has the primary and secondary VA being equal. Which contradicts the first method which says primary VA is 1.4 times the secondary VA.

So which one is correct?


texts:
We are designing PCB with multiple ICs (up to 10 ICs). Each IC has MDIO and JTAG interface. The board has two signal layers, one power layer and GND plane. We have to route JTAG and MDIO lines to each IC, so the tracks become pretty long and what is the main point of concern - there are too many vias between layers.

For example while I was routing JTAG TCK track to the last IC, I had to add 8 vias. As far us I understand each via adds some inductance to the line, so the high frequency components of the clock may be attenuated. Should we consider for the number of vias and trace length while routing JTAG and MDIO pins? And also how the number of vias influences the wave impedance?

Is it a good practice to route high speed nets like 100BASE-TX diff pairs using some vias? Or we must  add extra layers to keep the number of through hole vias less than two?


texts: How does a diode valve work based on this sentence?

texts:
In a diode valve, the anode would not emit electrons when heated so when the polarity of the voltage across the tube was reversed, no current flowed. Notice how the solid state transistor works in a similar way.

Why does the anode not emit electrons?
Why does no current flow when the polarity of reversed? Why reverse the polarity?
What is a solid state transistor? Just a normal transistor?
What do they mean by solid state?


texts:
I am running into problems creating a circuit that once a button is pressed ( clicked ) will latch and run for a few seconds and then turn it self off. This would be trivial with a MCU but now I am trying to do it with a monostable 555 circuit.

The idea is that I have a high-side mosfet acting as a switch, this is closed by the button. This should start the 555 timer circuit and now the switch would be kept closed by the timer output. And when the timer output is low again, the circuit will be inactive. This is the circuit I am trying to simulate using LTspice:

The timer is working if simulated, but now the simulation hangs as soon as the voltage controlled switch is triggered. Do anyone have any better idea how to achieve this functionality or how to get the simulation working?

Edit: I am trying to keep the power consumption to a minimum when the circuit is inactive, minimum meaning nano-Amps. The current draw when active is also good if it is low. But mostly the circuit will be off.


texts: How to I calculate the AC amperage draw of a 12 volt 3 amp AC/DC transformer under full 3 amp load?

texts:
I want to calculate the 120 volt amperage draw of my 12 volt AC/DC wall adapters, most specifically, one that has a 3 amp rating that is pulling close to 3 amps.

Is there a formula for calculating the AC amps?

Example: A 36 watt 120 volt load vs. a 36 watt 12 volt load on a 120 volt AC/DC converter. I want to compare AC amps of each.

I apologize in advance if my question is not clear, but that's the best I can do.


texts:
I have a PCB in front of me now, with the following circuit on it:

Despite looking fairly easy, this doesn't work as it should. After delving into some info about 8051 ports, I started to suspect that, despite measuring 4.9 Volts on the outputs, ports are actually not sourcing current, they are sinking. Then I saw this (page 138):

8051 Microcontrollers: Hardware, Software and Applications

Here, the author claims he is doing what I am trying to do. Is he right or wrong? Could this be done with the right choice of resistors? Or can this only be done with an PNP?