texts: Inferring a pipelined divider in Verilog

texts:
I want to synthesize an integer divider in Verilog to divide 16-bit integers by 8-bit integers. I assume that the compiler will be way more clever than me when it comes to implementing the details of the logic, so I want to give it a / sign and just let it be creative. I don't want an insane amount of logic with a huge propagation delay, so I'll obviously have it pipelined. I want to tell the compiler "you have X clock cycles in which to deliver me a result".

I suspect that this is possible because there's precedence for this in FPGA toolchains when it comes to inferring hardened, pipelined multiply blocks from constructs that look similar to what I have below (Xilinx example, Yosys example)

I have 2 questions that I'd like answers to:

Is the below enough to tell most Verilog compilers to generate a multi-cycle divider with whatever method it wants?
What's a pretty sane number of pipeline stages to offer the compiler? I'd think it would be the number of bits in the denominator (8 in my case).

`timescale 1ns/100ps

module pipelined_divider (input                                    clock,
                          input signed [width_numerator - 1 : 0]   numerator,
                          input signed [width_denominator - 1 : 0] denominator,
                          output signed [width_numerator - 1 : 0]  quotient);

    parameter width_numerator = 16, width_denominator = 8, depth = 8;

    reg signed [width_numerator - 1 : 0] pipeline [(depth - 1) : 0];
    integer i;

    assign quotient = pipeline[depth - 1];

    always @ (posedge clk) begin
        pipeline[0] <= numerator / denominator;

        for (i = 1; i < depth; i = i + 1)
          pipeline [i] <= pipeline [i - 1];
    end
endmodule

For reference, I'm aiming at a Lattice iCE40 FPGA at the end of this. The model I'm looking at has 5,280 logic elements, and they look like this:

I realize that the right answer here is probably "just try it and find out", however, when you google similar questions for programming languages and not HDLs, there are tons of answers about how to drop hints to a compiler to get it to do something smart. I wish there were more easily google-able discussions like that when it came to hardware synthesis, so that's why I'm asking.


texts:
I want to build impedance meter for measuring input-output impedances of audio amp stages.

Does anyone have experiences with such projects. I want to measure stages while running (hot measuring) so have an idea to inject 1kHz low level signal at one point and measure losses on another. Is it appropriate way to do measuring?

What do you think?


texts:
if i'm using Sampling frequency less than Nyquist Sampling frequency, Aliasing will occur which will scramble the whole signal, so one solution is to use anti-aliasing filter

How can i calculate it's Bandwidth, also is it a band-pass filter ?


texts: ATmega32 programming without external clock?

texts: I'm using an Atmega32. I want to use an external 16MHz crystal and I'm using a universal programmer (like http://www.kanda.com/products/wellon/VP-290.html). My question is: once I've programmed the chip and set its fuse bits to use an external oscillator, would I need an external oscillator when I'd want to reprogram its flash?


texts: 8051 Stop Mode -- External Interrupt Polling?

texts:
I inherited a physical product that needs to function like this using an 8051 in STOP mode.  My user manual is a little light on STOP mode, but I can't get this to work, does someone who has used 8051s can weigh in on this?

Desired Actions

Note: Button A is an external interrupt.

1)Hold down Button A, for five seconds.  Poll Button A every 5ms. After five seconds of polling, call the STOP(); macro.  System shuts down.

2)While system is in STOP mode, press Button A and and system turns back on.

The problem I have is that when I hold down Button A for 5 seconds, it triggers the STOP mode.  But instantly the system bounces out of STOP mode because Button A is still held down.

The datasheet (sketchball Asian 8051 MCU...) is not clear on the wake-up behavior.  In one place it says any input from any from anything on port 1 or port 0 will wake up the MCU from STOP mode.  That's not true.

It also suggests that the external interrupts can wake up the MCU.  That seems to be true, and explains why STOP mode isn't "sticking" when I use Button A.  If I switch the polling to Button B, a non-external interrupt button, the polling method works and the system goes to STOP mode.

What is strange with that behavior is that the Button A external interrupt is not enabled!  Global interrupts are enabled, but not any external interrupts. The behavior is really odd.

Is there some way I could use Button A to trigger the STOP mode, but not have it  immediately trigger an external interrupt and pull the system out of STOP mode?

(This was not a system issue with a PIC in an earlier design since it was polling buttons using some kind of deep-sleep watchdog type timer... sketchball Asian 8051 has no such feature).

UPDATE

Even though the datasheet does not state it, it looks like the watchdog timer and internal low power clock keep running in STOP mode.  There may be a way to jigger some variables to keep the system in STOP even when it is being retriggered.

SUGGESTED SOLUTION

I could enter STOP mode, when the button is held for five seconds and then released.  That would work, but requires a product manual rewrite.

FINAL CODE

Triggering the STOP mode on the button release works well.  One thing that is not ideal is that you end up having to spoof that the unit is on/off, so the code logic is that you hold Button A for five seconds, at five seconds the display turns off BUT the unit is actually still running.  It appears to be off, but when you release the button the unit actually goes off.

There ends up being a lot of code logic behind the scenes to handle all the edge cases.  Like if someone taps the Button A, once it is off, but doesn't hold it down for 5 seconds.  You need to capture that and shut the system down again.


texts:
a couple of days ago I had a discussion with a colleague when he told us he purchased a "WiFi Booster Adapter+Antenna". It was claimed that by plugging it in his USB and using it instead of his built-in WiFi adapter, he'd be able to connect  to those "far away wireless networks".

My assumption about WiFi (or any form of 2-way connection):

The two devices should be in each other’s range.
There's no such thing as "receiving range".
Even if you boost one device's transmission range while the other device is moving further, you should also do the same boosting (more power gain) for the moving device.

Based on those assumptions I have the following in my head:

(Both devices in each other's range; A's signals are reaching B, B's signals are reaching A)

(B is going further and boosting its signal. While B's signals are reaching A, A’s signals aren't reaching B)

The question is: away from the discussion itself, the brand of the booster or where he's installing it (one might purchase a super duper WiFi AP for example). Am I making wrong assumptions here? either about how sending/receiving signals works or how the booster works, if so can you please correct me?


texts: Processing an analog signal to square wave using a SN74LS14 Schmitt trigger?

texts:
I'm looking at using the SN74LS14 for turning a 3V peak-to-peak audio signal to a square (rectangular) wave. If my reading is correct, the positive-going threshold (V_T+) is 1.6V and the negative-going threshold (V_T-) is 0.8V. Since the input has a 1.5V peak, which is less than V_T+, would the output be a constant LOW? If so, is there a more appropriate Schmitt trigger for a 3V peak-to-peak signal?

In fact, what's SN74LS14's recommended input voltage? I can't seem to find it anywhere.


texts: How to determine a capacitor value across a switch carrying DC

texts: The tiny rocker switches I'm using in a current project are supposedly good for 3A DC, which is at least 2X what I'd expect to draw worst case. It is supplied from a hefty Li-ION battery source nominally 12V, and these are cheaply made switches. So I'd like to include a capacitor across the switch to prevent some of the likely arcing when the switch is opened, and hopefully give the contacts better longevity. Is that reasoning sound and if so, how would you approximate a reasonable value for the cap?


texts: Will soldering jumpwire to DC Booster USB circuit work

texts: I wanted solder 2 pins to the positive and negative holes of this usb booster circuit, but I am not sure if it will still work. Please, will the connection work if I do this? Thank you for any help!


texts: How do I build a switch to automatically control my shop-vac?

texts:
I'm starting to get into woodworking and I've run across some high-end dust collectors and shop vacuums that turn on automatically a second after the tool plugged into them (such as a table saw) is turned on. When the tool is turned off, the vacuum stays on for a few seconds longer, then shuts off automatically. There are also aftermarket switches like the iVac that do the same thing.

It seems like I would need a normally-open 120V relay to turn on the the shop vac, but how do I delay turning on the vacuum, then make it stay on for a few seconds longer after I turn off the tool?


texts: Op Amp in buffer configuration is decreasing output voltage

texts:
I have a 4.24V DC signal which I have to apply a buffer in the purpose of have a high impedance between the 5V signal and Op Amp output. My circuit is like following:

The problem is that my output voltage presents aproximattely 3.8V

Why the Op Amp in buffer configuration is decreasing the output voltage?

PS: I'm using an Op Amp Single Power Supply (I tried with LM324 and LM358)


texts:
I was trying to use a DM-4100A multimeter to verify a power supply, and I'm not sure I'm using the multimeter correctly.  The multimeter is >10 years old too, so maybe it is not working correctly.

When I set the meter to measure AC voltage, with a 500V or 200V max, it reports 170-175V.  I was expected more around 120V  (I am in the USA).  Is 170V an expected voltage, or would that suggest I'm doing it wrong?

UPDATE:  It sounds like it may be reporting peak voltage instead of RMS.  The multimeter does not seem to have an RMS setting.  Can I just take the voltage and divide by 1.414 to get the RMS voltage?  I want to do this for the purposes of verifying whether power adapter is still producing the correct voltage.


texts: Export restrictions on programming equipment

texts: I have a friend that works for an overseas manufacturer. He sells programming equipment to companies that have products with multiple Programmable Controllers embedded. I raised the subject of "export Control" requiring a special export license, and he stated that he required none to re-ship to Mexico. I used to work for Tektronix and recall a lot of paperwork to obtain the proper permits. Where is the line between simple logic ICs and more sophisticated components?


texts:
This is uc3845 IC which use for control PWM in power supply.
I see this set up on datasheet for testing and I want to set up this on breadboard for better understanding how this IC work, but I don’t know VREF voltage. How much voltage VREF should have?
Regards.
Plus, I don't know COMP pin use for, can anyone explain it to me?


texts: L4978 voltage regulator feedback resistor values

texts: I am trying to use a L4978 to create a 6 V regulator. I, however, am unable to find how they calculate the resistor divider in Figure 4 to get a given output voltage. Does anyone know how they are calculating this?


texts: Single step debug and timer's counter value

texts: I am debugging with cortex m7, i found that when I halt the CPU, the timer's counter value still upward increases. After reading it's reference maunal, I found a register that can stop timer's clock feed when the debugger halts the CPU. However, even I configure this register, I still got counter value increases for about 15 in disassembly single step(timer clock is same as cpu's). Is this the same for all microcontroller? So I can only see the right behavior in simulator? Thank you!


texts: Wirelessly power multiple LEDs with antenna?

texts:
I'm working on a project that requires me to build an antenna and I'm not very experienced with wireless transmission.  Here is an overview of my project: Four parking spots for cars with pressure plates that produce roughly 4 or 5 volts when a car is parked in a spot.  (this is small scale - think model car size) Since the 4 volts indicate that a car is parked, we want to send that signal to the entrance of the parking lot that lights up an LED indicating the spot is taken.  The distance between each spot and the entrance would be roughly 3 feet max.  There would be a LED for each spot

We were thinking of using an oscillator to convert the voltage to a signal that can be transmitted through an antenna.  Something like this: https://www.sparkfun.com/products/9089
I did more research and found this chip that supposedly converts voltage to frequency and frequency to voltage which would be perfect for this project (again, I'm not experienced with wireless transmission - this could be wishful thinking)
We wanted to use a microchip antenna so we can solder on a PCB.  Here's an antenna example: https://www.sparkfun.com/products/144
So would we need a receiving antenna with the same Hz as the transmitting antenna? I'm assuming I could solder the receiving antenna to the frequency input, or is that completely wrong?
I assume we would need a different frequency for each parking spot sensor so the corresponding LED would light up.  Does that sound correct?

My main questions if you guys can't answer the few in the paragraph before is this:

What antenna (or antennas if I need multiple ones) would I look for to transmit the converted voltage/frequency
Would I need extra parts to help transmit the frequency and receive it?

Thank you for your patience and your expertise, every bit of knowledge helps and I appreciate any input.  Thank you!


texts: Suggest mini project for feedback and controls that can be simulated in LabView

texts: im an electrical engineering student and Im having problems on my feedback and control subject. all of my proposals for project are being denied. can you please suggest electronics that can be simulated in labview? thanks .


texts: How can a DC supply be given to the transformer primary in a flyback DC to DC converter? In a flyback converter there is a transformer and DC supply is given to it. How?


texts: What will happen if I put a small resistor in series with a large motor and 24V battery?

texts:
Here's the small resistor

Why: I need to measure current drawn by a large motor (from electric lawnmower), but my multimeter has a max rating of 10Amps. Workaround is to attach a known resistor in series and measure the voltage drop across the resistor, then use ohms law to solve for current in the circuit.

This resistor has a power rating of 250mW. Based on other lawnmower motors, I am assuming this is approx a 350W motor, and with a 24V source, the current will be around 15Amps (using P=IV).

Question: If I place such a resistor into the circuit, will the resistor blow up, or will it SAFELY dissipate whatever small amount of energy it is capable of absorbing and let the motor take the rest?


texts: Can I increase DC voltage using capactiors in series and then use a voltage regulator?

texts:
I am (re)learning electronics and I am currently playing around with "simple circuit" to practice a bit.
For testing, I am doing a simple circuit that could have 2 different input voltage (not at the same time), one from a 12v and one from a simple Li-Po (3.7v).
As I want 5v I use a simple step-down voltage regulator for the 12v.
Regarding the battery, I know I could use a step-up voltage regulator, but I would like to know if it was "ok" and "safe" to use two (same) capacitors (non-polarized) to increase the voltage output voltage of the battery, and then use this "boosted" voltage inside my 5v voltage regulator.
So I avoid to use 2 ICs for a "simple" tasks.
Also, to learn a bit more, what would be the drawback of this solution even if it is "OK" to do it ?
N.B.: I know that step-up/step-down voltage regulator exists, but I do not own one and these ICs seems a bit more complex than "simple" fixed step-down voltage regulator. So for now if I can still use my step-down voltage regulator it would be great.
NB2: Li-Po have an integrated circuit to protect from overvoltage, so I suppose it's ok to boost the voltage


texts: How could one "inverter control" convector heater be more electrically efficient than another?

texts:
I'll have to explain it step by step so that you have no chance to misunderstand what I'm asking about.
First, what a convector heater is. It's a plasma TV shaped box usually made of sheet steel. There's no plasma TV in there, it's hollow. A set of holes is made in the bottom side of the box. Another set of holes is made either in the top side or in the front side near the top of the box. A resistive heating element is installed inside the box near its bottom. The box is either mounted onto a wall or installed on small wheels or legs. The heating element is connected to AC mains so that it can draw electricity and produce heat which heats the air inside the box and causes convective flow of air through the box. So it's yet another way to produce an old boring electric heater.
That was an unregulated heater which would either underheat or overheat the room most of the time. So a heater is usually equipped with a thermostat which is mounted somewhere on the box. A thermostat may have a rotating knob and a bi-metal plate or it may be an electronic thermostat which has some electronic circuits and button controls to set desired temperature. Either way it cycles the heating element on and off. So the heater is either fully on and producing heat or it's off and it's cooling down to room temperature.
Now welcome an "inverter control" heater. It's the same heater as above but now it has some clever electronic circuit that can run the same heating element at different power levels. I cannot find the details of how exactly it's implemented (and if I could I'd rather not understand them) but it sound very similar to how LEDs are driven with a switched mode driver - exactly the right average power is applied to the heating element and so it's always "30% on".
Then there're two very similar convector heaters - nearly the same shape and size, same power and both with "inverter control", produced by two different manufacturers. Some dealer claims that a certification lab tested both heaters and one of them turned out to be seven percent more electrically efficient than the other. I don't know what exactly "electrically efficient" means but the dealer frames it such that the "better" heater will consume less electricity for the same amount of heat.
How could this be possible? If it were LEDs than the driver losses would be useless (and even harmful) heat. This time heat is useful and it doesn't matter where heat is produced - in the heater or in its control unit which is attached to the heater. Either way it should produce one kilowatt-hour of heat for every kilowatt-hour of consumed electricity.
How could one heater be "more electrically efficient" than the other? Is it technically possible?


texts: I am lost with how to approach part C and D of the question. In fact, I need some intuition with how to tune a differential amplifier.


texts: Electronic component which produces a clear clicking sound

texts:
A surprisingly hard thing to search for as most references are to defects with other components.

Are there any such devices mass produced? or any good alternatives.

I've considered over-driving a relay and short spikes to a piezo but I'd doubt the life-span of the first and dislike the result from the second.


texts: Is it possible to step up dc without changing it to ac or pulsed dc?

texts: I've been looking at dc to dc step up converters/voltage multipliers, and they all seem to make it ac or pulsed dc and reconvert it to dc at the end. Is there a way to step it up directly? A clock circuit is pulsing dc, for whoever got my question closed.


texts: Why does the value increase constantly and slowly in diode mode?

texts:
I am using Fluke multimeter and trying fix electronic circuit. In diode mode fluke docs, telling briefly explained how to test the durability and accuracy of diodes. The test usually runs when I touch the probes on the circuit to the anode and cathode of the diode. and it shows a value of 0.6 volts on one side and the OL value appears when I change the probes side.

but things are not going as usual. in a different electronic board, When I touch the probes to the diode again it writes 0.6 volts. but when I change the location of the probe slowly and I encounter an ever-increasing voltage value. I wonder what they might have connected on the circuit in parallel with the diode, or if we assume that the diode is intact, what short circuit might have been in the circuit. do you have any idea

Whatever possibility I tried out of circuit, on the one hand a constant voltage, on the other hand slowly and continuously increasing voltage when I change the place of the probe, I could not design. Why do you think I see a constantly increasing voltage value when I change the probes?


texts: Dimmer with zero-crossing circuit and TRIAC

texts:
I want to make a dimmer to control a huge power resistance of 700W. For this, I made a circuit that detected when the wave reaches zero (the circuit above the figure) and another that controls the TRIAC that controls the current that goes to charge.

The zero detection circuit is working fine, but the control circuit does not. I'm controlling everything for Raspberry. The code is only a function that is triggered by the interruption of zero detection. This function waits a certain time (depending on how much I want the wave to pass) and then a pin (which is what goes to the optocoupler and then to TRIAC). However, regardless of the time I put to wait, the output is always the same as the AC input, ie always 220V. Do you have any idea what might be happening?

I've already checked that Raspberry is sending the signal correctly and it is. So I think the problem is on the TRIAC or optocoupler side.

I'm using this components:
R2,R8=180R ¼ w, 180R 1w
R6,R4=680R ¼ w, 680R 1w
R5=39R 3w
R5=56K 1w
R7=10K ¼ w
R1=1M ¼ w
C4=100nF
C3=100nF 230V ~
C1=10nF 630V~
U1=MOC3021
U2=4N35
U4=BT136
Q1=BC547B

Thank you!!


texts: Relationship between base resistor and collector current in this unbalanced differential amplifier

texts:
For this BJT circuit, I was wondering if there was a solution for how the collector currents change with respect to the value of the single base resistor.  This arrangement popped up in a circuit I was trying to understand and I noticed that my DC analysis was wrong because I couldn't figure out how to account for Rb.

The simulation shows the expected result of splitting the bias supply equally among the transistors for a zero ohm base resistor and as the resistance increases the T2 base current is reduced causing the bias current to be shunted to the T1 transistor.

So far I have come up with \$Ic_2=\frac{\alpha I_{bias}}{1+e^{I_{B_2}R_B/V_T}}=\frac{\alpha I_{bias}}{1+e^{I_{C_2}R_B/\beta V_T}}\$.  Can this be simplified? Am I on the right track?


texts: L200 regulator power supply circuit design help!

texts:
So here is the thing, I'm far from an expert in electronics, I'am pretty good with following a schematic but not designing one.

I have made a power supply based of the LM317 that worked out pretty well. But now I wanna try it out with the L200 regulator. The problem that I have is that there is no simulating model for the L200 (Using Multisim). And if I can't simulate the circuit I have a hard time testing different stuff.

So I would really appreciate if anyone have some time over and could draw me a circuit that will fulfill my purposes.

L200 Datsheet & L200 Designers Guide

PSU requirements:

Voltage adjustment: 2.8V - 30V.

Current Adjustment: 10mA - 5A

The hard part:

I want to make the current go through a 2N3055 power transistor, the datasheets does not say how I can make both voltage/current adjustment + using an NPN transistor.
I have pretty much infinite space to build the power supply in so I can fit in a BIIIG heatsink without any problems.


texts:
Which is the best circuit for using a magnetic contact for turning on a LED strip?
I would like to turn on a strip led with 12V 7A battery, but:
 1 - if I use only the magnetic contact it will be burned (when the contact is closed the LED strip have to be off so in this way I put it to ground, is it right?) (yes this is a short circuit, I'm not using this way)

simulate this circuit – Schematic created using CircuitLab

2 - if I put a resistence it works but the strip led has low power:

simulate this circuit

3 - if I put the resistence only for the magnetic contact, when it's closed the LED strip is ON (instead should be OFF)because the current goes the same through the LED strip (I think it has a lower resistence)

simulate this circuit

4 - I thought I should use a transistor between the strip led and the magnetic contact but it's not enough..
Should I use also a relay?

Can someone help me? Am I thinking in the right way?


texts: Electrical motors' properties regarding Stall torque

texts: Is there's any way, or any type of electrical motor, that can have a Stall torque, meaning a torque produced while having its output rotational speed lowered or zero, without damaging the motor? like with our arm we can hold a cup in the air, having the constant force output to hold the cup in its place, and we can even add water to the cup, increasing the necesary force output from our arm, without damaging the arm. Is this possible for any type of electric actuation?


texts: Choosing proper CCS current for discrete transistor amplifier's differential and VAS stages

texts: Here is a figure from "Audio Power Amplifier Design" by Douglas Self. Self using almost same current values (4mA and 6-8mA) in many examples without explanation. How to choose these values properly for my own design?


texts: Code Composer Studio v4 and MSP430 development

texts: Does anyone have experience using CCSv4 to program for the MSP430 chips? I know msp-gcc is out there, and I'm sort of kicking myself for not using it, but at this point I'm stuck with CCSv4. I was drawn in by the fact that it was built on Eclipse, but I'm uninspired by the level of library/header file support that exists. I've had very little luck in even getting the UART to work correctly, and I won't even go into my struggles with printf. Does anyone have any advice on making the most of CCSv4 for MSP430 work? Maybe it's just me and I haven't tapped into some awesome resource yet... (I've already seen the MSP code examples provided by TI for my MSP430 family, and I've signed up on TI's e2e community...)


texts: Why do current transformers have a minimum frequency rating?

texts:
Datasheets of current transformers usually specify a working frequency range. In other words, they specify a minimum and maximum frequency for normal operation.

I understand that the core losses grow exponentially with frequency. So the datasheets give an upper limit for frequency. But, why is there a lower frequency limit? What happens when we apply an AC current to the input of a current transformer with a frequency lower than the rated minimum frequency?

An example product:
EPCOS B82801B Series
Frequency range: 50 kHz ... 1 MHz


texts:
I would like your suggestion on my first design Differential signal modulator [simulation attached].
Before jumping into design let me highlight my objective.  I am differentiating a control signal of 1MHz and then modulating it with carrier frequency 15MHz(not limited to this specific value but for testing). The whole modulator needs to be integrated on a silicon substrate, in other words, the design should comply with IC design regulations i.e. occupy less space, power-efficient, and simple. The current design consumes 5.6mW power.
So I would request suggestions who had experience in a related field, that
1-How can I further improve this design?
2-Is there other alternatives design that would be much better than this one?
Your suggestions and comments will be highly appreciated. Thanks


texts:
Was wandering whether anyone could suggest how to solder stainless steel. I know hydrochloric acid flux is suggested to remove oxidation. Anyone could suggest a supplier in UK or who would be able to deliver to UK.

The part we have is a folded miniature box (approx. 2x4x3mm). We require to close up 2 gaps of stainless steel material by soldering the surfaces together, however conventional flux does not seem to work...

If anyone has any suggestions on technique or super aggressive flux supplier suitable for this procedure I would be most grateful for advice.

Thanks in advance.


texts:
On the diagram below, there are 4 PNP transistors.

When RA0 is set to HIGH, then current flows from +5V through RA0 to GND and from +5V through 7 segment display, then through (for example) RB0 (if it's set to HIGH) to GND. Is that right? Is setting a processor pin to HIGH state means the pin will allow current flow from the voltage source to GND through itself?


texts: Identify this two-terminal SMD electronic component 16C95A

texts:
Please if anybody can identify this electronic part as it is burnt and I need to replace it. Your help will be so much appreciated!
Electrical interface RS-485, 2-wire. Supply voltage [V] 12 - 27 VDC.


texts:
The PM motors specially BLDC or PMSM they get their armature energy from the permanent magnets on their rotors unlike the Induction Motors in which the armature gets its energy from the Stator rotating flux. So we can say that PM require less current or energy or power as compared to IM for same work.

Does it means that when energy of PM is used to do the work then at the same time the magnetic flux or field or strength of the PM gradually reduce as it supply the energy to do the work in the motor action?

So if the magnets keep losing their energy then after certain amount of hours-of- working they will de-magnetize and a PM will not run. Please correct me if I am wrong in this understanding.


texts:
If two conductors (A and B), separated by a distance R, are parallel for a length ℓ and conductor B has an AC current flowing through it (I), what would be the equation to calculate the EMF (voltage) induced in conductor A between points 1 and 2.

To help clarify the question, I will give the following example inputs:

Conductor B is AWG 4 (5 mm) diameter single core cable. (It is carrying an AC current of 10 A (RMS) @ 50 Hz)
Conductor A is an 8 mil wide 1 oz PCB copper trace
The length ℓ between points 1 and 2 is 50 mm
The gap between the centre of the conductors A and B (R) is 5 mm
A complete path (not shown in the diagram) exists such that current can flow in conductor A
The medium between the conductors is air


texts:
I'm referencing this Fairchild semiconductor datasheet on the TIP112.  (I'm actually working with a TIP110) and trying to evaluate the gain.  In the specs grid on the second page, the sheet states -> 4V Vce/1A Ic the gain is 1000 and at 4V Vce/2A Ic the gain is 500.

However, the graph on the next page (figure 2) is quite contradictory to these statements.  Can anyone confirm that this is a typo?


texts: Toggling 9A with ATtiny85 single-button-latch

texts:
I'm trying to use a nice one-button On|Off latching setup on ATtiny85. See for details the last one of these four: http://www.technoblogy.com/show?VOO
In a low-power set-up on my breadboard this is no problem; works like a charm and allows for any delayed auto-off.

However, I want to use this for powering up/down my 400W Ebike.

My question is: how to boost the signal from ATties peak 40mA to an acceptable current that can switch a FET or a relay?

I considered diverse alternatives like transistors or 555 based latching schematics, but choose this one since I have an ATtiny on board already.
I have zero experience with FETs or MOSFETs, and I'm stuck.

In this thread (avrFreaks, post #6) a BS170 is mentioned, but I cannot simulate the right circuit and I do not understand yet fully what's going on in that MOSFET.

I have considered using a relay, but these are hard to find in an acceptable price range with specs needed (small footprint, shockproof and allowing to switch 10A at 42V). So I think MOSFET is the way to go.

A detail from the schematic of the on/off wiring:

PB0 is set high when system is powered up and needs to switch the 42V.
Plz feel free to make any changes on the isolated (simplified) part of the schematic on EasyEDA:
Go to schematic

Any help will be highly appreciated!


texts: Selecting between 60V source and 1uV measurement

texts:
My goal is to perturb a sample with a 250us pulse of 100mA at 60V, then on the same probes measure the response over time in microvolts. The pulses will be repeating at about 100Hz, so most of the time measuring. The response and pulse will be AC, or +/- compared to resting state. Switching time should be 10us or less.
How can I protect my instrumentation amplifier from the 60V pulses, wouldn't using limiting diodes also limit the pulse to my sample? I'd prefer a switch or multiplexer like solution so I can use the same electronics for multiple probe pairs. Would triacs and the like result in a voltage drop, negating my uvolt measurements? Or does someone know of a component for this. A relay would have the range for this, but not practical for the switching frequency. Any other options?


texts: When to use Nodal Anaylsis / Mesh / Superposition?

texts:
I'm studying these three methods and i'm confused on exactly which one is used when. This is a very broad question. Therefore, could some explain in general terms the difference of the three methods as this might bring some clarification to me instead.

As I'm understanding Mesh analysis is KVL and Node analysis is KCL? Am I right here or wrong? Where does superposition come from?


texts: Switching a relay from its supply (2 Relay Module, VCC to IN1, doesn't work)

texts:
I searched far and wide but couldn't find an answer to my question.
I've read the datasheet and I've look at schemes.
I'm not very experienced with electronics.

This is the module I will be talking about:

Let's say I apply 5V to VCC from a given power supply, and then connect the ground. If I short IN1 and IN2 with VCC, nothing happens. Why is this so? Logic dictates it should, because when an Arduino controls the relay it powers the relay from 5V and then uses the same power supply to switch the relay with a pin connected to IN1 and IN2.

Why wouldn't it work with a simple 5V power supply? The power supply I used was my phone's adapter, it delivers exactly 5V.

Is there a way to short something to make it work?

Here's my scheme:

The scheme's idea is to switch between 5V from the wall and 5V from a battery. If power from the wall is available, then the battery is disconnected and recharged, if power is out then the battery kicks in.

I know MOSFETs will probably be better in this case but I've already soldered the thing.

Thanks!


texts: What is the relation between transresistance and input impedance of a transistor?

texts: What is the relation between transresistance (i.e. inbuilt emitter resistance of a bjt) and \$h_{ie}\$ of a transistor?


texts: Creating DIY ON/CHARGING switch for an Arduino

texts:
Currently I'm using the newly released WEMO LOLIN32 (pictured below), and it's a great board, save for the lack of one thing, a power button.

Initially I was thinking of a simple ON/OFF switch that disconnects the battery, but I realized I need it to be able to charge a Li-Po battery while the device is powered down. Now since I'm charging a Li-Po I need to output 4.2V to the charger (at say 50-100+ mA or something comparable to the current from the battery terminal). Sadly as this is a new board I don't have much in the way of a spec sheet to guide me on the capabilities of each port.

Two questions

Will I fry the board if I try to run power through analog out ports?
Is there charging behavior that is built into Li-Po charging that I need to emulate on the analog out that I use?


texts: Christmas light transformer (500 LEDs, 31V, 0.06W)

texts:
I have a set of 500 LED Christmas lights for which I want to replace the power suply. The tag on the lights reads:

Lamp: 3v - 0.06w
Transformer: 31v - 3.6va
Set rating: 31v -3.6W

Is there a standard LED driver I can use, and if so what do I need to look for?


texts: Finding a XT60 connector switch with indicator lights

texts:
I'm looking for an XT60 connector switch (e.g. https://www.amazon.com/gp/product/B07K33LRW2/r), but need one with an indicator light so I can visually verify whether a current is flowing through the circuit (reliability concerns). I see similar switches w/ indicator lights but for other types of connectors (e.g. https://www.amazon.com/Apex-RC-Products-Pack-Switch/dp/B01BQURNBQ/)
Context: connecting external battery to an OneWheel+ XR, and had reliability issues with switches in the past.
Current Requirements: ~60V, ~5A
I looked online for about two hours, and wasn't able to find either:

a XT60 connector switch that had a LED indicator built-in, or
a stand-alone XT60 connector LED indicator (except for https://www.readymaderc.com/products/details/STRIX-XT60-RGB-LED-Tap, which requires soldering tools that I lack)

Would love some pointers for either of the above, or general advice in steering me toward other investigations.


texts: Why doesn't this transistor circuit work as expected?

texts:
This is a circuit I have designed to work as an oscillator. But it doesn't work.

The way I supposed this works:

When power is ON, the capacitor(C1) starts charging through 1Kohm resistor. Once it reaches 0.7 volt, it trigger the Q1 which will almost short the point A with ground. This makes the C1 discharged which will switch Off Q1. The operation repeats. But This doesn't work and I am always getting the base voltage as 0.7v.

What is the mistake I am making?

Note: I have not connected any LED or speaker to this circuit. I just used a DMM to check the base voltage to see whether it is fluctuating.


texts: Identifying direction of rotation for a three phase motor, without applying three-phase power

texts:
Suppose I have a typical smallish (say, <3kW) three phase induction motor. Likely 400V star-connected, but methods that work with any motor would be preferred.

I can ensure that the supply phase rotation is in whichever order I like, but would prefer not to need to alter the motor once installed, which will be before power is applied. So guess-and-check once livened is not feasible.

Three phase power is not available during installation, but single phase 230V power could be. I can spin the motor by hand or by power. Reaching operating speed is not required, only enough to determine direction.

How can I identify which way the motor will spin with a given supply phase rotation?


texts:
I have an ESP8266 01 board
GPIO16 is connected with a reset pin because I'm using deep sleep functionality. I want to have a push-button connected to GPIO2. This button should behave as a board factory reset as well as board restart. It's my own custom "factory reset", not actually the esp factory reset.
I've programmed it like:

If the button clicked while normal working -> soft restart the board (gpios settings remain)
If the button clicked for about 3s while booting -> do the factory reset

What the user can see?

short press -> restart the board and perform an action
long press -> restart the board and perform a factory reset Both actions have to work even when board deep sleeps.

Unfortunately, there are two issues that I can't resolve.

After the board wakes up from deep sleeping, GPIO2 can't be held to the ground because it has not been configured yet. Board won't boot in such case.
My board sleeps most of the time (let's assume 10min of a deep sleep, 20s of working). The user would have to hold the button 10min in the worse case till board boots up (of course there is still an issue number 1).

So, for now, it works only when the button is pressed while board is working (about 20s).
The solution which I have thought about based on some analog circuit with resistors and capacitor.

pull RST pin as well as GPIO2 pin high
Button pressed, then:

pull RST pin to the ground (through some resistor) it will also work for deep sleep,
pull RST high, board is booting
pull GPIO2 pin to the ground but after some time, when GPIO2 os configured

Button release:

pull RST pin as well as GPIO2 pin high

It could be possible using a simple RC circuit, but it is difficult because the RST pin has an internal pullup and it is driven by a rising edge.
Or maybe there is a much simpler way to achieve that. Maybe I miss something.
The assumption is that I want to have it as simple as possible without any other integrated circuits.
Basically, I need something like below (GPIO2 can be inverted, whatever is easier):


texts: USART interrupt not working as expected [STM32 Nucleo]

texts:
could someone explain why i can only receive 13 chars with USART interrupt? I use '\n' to detect the end of string.

#define BUFFER_SIZE 100

char receive_buffer[BUFFER_SIZE];
char receive_data;
int receive_index = NULL;
int data_ready_index = NULL;

void USART2_receive(void const * argument){
         for(;;){
                if(data_ready_index == 1){
                HAL_UART_Transmit_IT(&huart2, (uint8_t *)"Received data: ", strlen("Received data: "));
                HAL_Delay(50);
                HAL_UART_Transmit_IT(&huart2, (uint8_t *)receive_buffer, strlen(receive_buffer));
                memset(receive_buffer, NULL, sizeof(receive_buffer));
                HAL_Delay(50);
                HAL_UART_Transmit_IT(&huart2, (uint8_t *)"\r\n", strlen("\r\n"));
                data_ready_index = NULL;
                }
         }
     }

    void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {

        if (huart->Instance == USART2){
            if (receive_data != 13){
                receive_buffer[receive_index++]=receive_data;
            }else{
                    receive_index = NULL;
                    data_ready_index = 1;
                    // Received data ready to be processed
            }
      }
    }

    void USART2_IRQHandler(void){

      HAL_UART_IRQHandler(&huart2);
      HAL_UART_Receive_IT(&huart2, (uint8_t *) &receive_data, 1);
    }


texts: can I drive 100 or so LRAs with WS2811 controlling DRV2603?

texts:
I would like to make a suit with 100 or more individually controllable Linear Resonant Actuators. Texas Instruments makes this http://www.ti.com/lit/ds/symlink/drv2603.pdf which take a PWM as an input to control the vibration intensity. I'm wondering if instead of lighting LEDs with http://www.adafruit.com/datasheets/WS2811.pdf could one of these be wired to 3 DRV2603s?

Looking at the data sheets, it seems the DRV2603 accepts a PWM between 10 and 250 khz. I'm not clear on what the WS2811 outputs. The datasheet reads 400 or 800 khz but that is operation freq. Here www.world-semi.com/en/Driver/Lighting_LED_driver_chip/WS2811/ I see 2.5khz scanning freq, so I'll assume that.

The other hurdle I see is digital input high current max of 3uA on the DRV2603 while the WS2811 has a constant current output of 18.5mA. I assume that would fry the DRV2603.

Are these totally incompatible? How would the DRV2603 treat a PWM of 2.5 khz? Would I get 25 levels of intensity instead of 255?

How does constant current work? Is there a way to make this chip output less current? Could I maybe drive an led and then throw a resistor in parallel with the LED to drive the LRA as a side-effect of lighting the LED? I've seen Running Man and I know that would look good at least.

I'm certainly open to more proper solutions but this seems appealing for the price of these components. I am planning on using an Arduino with adafruit's neopixel library if this approach proves feasible. The arduino will be used to communicate with a computer over USB serial, so if an alternate solution involves some kind of USB to lots of PWM outputs, that would be great too.

Thanks for any pointers.


texts:
Which one of these is the phase 1? And why isn't there a neutral wire at all? The cable is Chinese. The device it powers is a 3-phase motor that powers hydraulics. I am sorry for asking this question here, but I don't know a better place. I have never come across this kind of color code. There is a connection between the black and the grey cable resistance is 230 ohms.

To put my question in a more technical way:

is it possible, from just the view on the colored wires in the motor cable, to deduct the internal design of the motor? What if I measured the DC resistances between all these four wires with a simple multimeter?


texts: low signal relay, how much voltage and current is possible to pass

texts:
I am working on a clapper (original, i know) and need to pass 230 V AC, to power a light bulb. For this i am thinking a relay is the right choice, but i am struggling to understand the specifications.

For now i am in possession of this relay:

https://www.omron.com/ecb/products/pdf/en-g5v_2.pdf

It might be a poor choice for mains voltage, but lets take it as an example to understand the specs.

It states a max load of:

0.5 A at 125 VAC

2 A at 30 VDC

And a max switching voltage and current:

125 VAC

2 A

What is the difference between load and switching voltage/current?

And if i need to power a 60 W light bulb, with 230 V, will i just need a relay that can handle 230 V and ~0,3 A at max load, and as switching?


texts: Can a computer monitor output light invisible to the human eye?

texts: From what I understand a computer monitor can output lots (couldn't think of a better word) of colours. Is it possible for a computer monitor (television etc) to output light invisible to the human eye?


texts:
I'm trying to design a circuit where it is essentially a motor controlled by a microcontroller with some feedback. The motor will have its own isolated power supply and the actual on/off switch will be a relay + transistor.

What I'm looking for is to have some sort of feedback if the motor side is not working (power supply is dead or wire break, etc), as currently if the controller switches the transistor/relay, there is no way of telling if there is current going to the motor. The motor may also be far away (let's say a meter or two) as well, increasing the chance of a wire break.

Currently, the only way I can think of doing this is to use an optocoupler with a current divider in parallel with the motor line. I have no idea if this a proper way, but I have gotten it to more or less work (with some guess work + trail and error on the resistor values). An issue is though that it is not perfect as I'm guessing when the motor is turned on/off (spinning up or spinning down or stall), the current draw changes which affects the reading a bit.

What would be a better/proper way to do this? Or what should I look up, as trying to search this in google just returns many results on how to measure current using a meter or using the continuity test.

simulate this circuit – Schematic created using CircuitLab

Side note: My knowledge in electrical engineering is pretty limited and my schematic is pretty rough just to get the idea across: I've omitted some parts, like the diode across the relay coil/motor and the transistor might be wrong one, etc.


texts: Thevenin's theorem BJT derivation question

texts:
I'm trying to convert the left circuit to the one on the right using Thevenin's theorem, but I'm not understanding how this is done for this circuit.

From my understanding of Thevenin's theorem:
(1)You disconnect a load resistor R_{L} and calculate the open circuit voltage v_{oc} where the resistor would be.

(2)Then short the voltage source and find the thevenin resistance R_{TH}.

(3)Replace the original voltage source with v_{oc} in series with the thevenin resistance R_{TH} connected to the load resistor R_{L}.

In the below picture, what is the load resistance that is removed and what are the terminals where V_{oc} is measured?  How specifically is +5 volts found to be the open circuit voltage?  How specifically is the thevenin resistance calculated in this image?


texts: How to improve the system verilog testbench for JK flip flop

texts:
I have a system verilog module as shown in (a) which passes the testbench in (b) but this should be the case as this is not the correct implementation. Correct implementation shown in (c). I am missing anything or any suggestions. Also, in my testbench I will like to get rid of the correct JK flip flop code block as the current testbench is dependent on it.

a)

module jk_ff (input j, input k, input clk, output logic q);
 always @(posedge clk)
 case ({j,k})
 2'b01 : q <= 0 ;
 2'b10 : q <= 1 ;
 2'b11 : q <= ~ q ;
 endcase
 endmodule

b)

`include "jk.sv"

module tb_jk();

    // open fitness file
    int passedFile;

   reg j;
   reg k;
   reg clk;
   wire q;

   logic q2;

   always #5 clk = ~clk;

   jk_ff    jk0 ( .j(j),
                  .k(k),
                  .clk(clk),
                  .q(q));

   initial begin
     $dumpfile("test.vcd");
     $dumpvars;

    // open file
    passedFile = $fopen("passed.txt", "w");
    //if(!passedFile) $display("error");
    //if(passedFile)
    //  $display("file opened");
    //else
    //   $display("couldn't open the file");

      clk = 0;
      j = 0;
      k = 1;

      #10 if(clk == 1 && j == 0 && k == 1 && q === q2) $fdisplay(passedFile, "%d", 1);
         else $fdisplay(passedFile, "%d", 0);
      #10 j = 0; k = 0;

      #10 if(clk == 1 && j == 0 && k == 0 && q === q2) $fdisplay(passedFile, "%d", 1);
            else $fdisplay(passedFile, "%d", 0);
      #10 j = 1; k = 0;

       #10;  if(clk == 1 && j == 1 && k == 0 && q === q2) $fdisplay(passedFile, "%d", 1);
             else $fdisplay(passedFile, "%d", 0);
      #10 j = 1; k = 1;

      #10 if(clk == 1 && j == 1 && k == 1 && q === q2) $fdisplay(passedFile, "%d", 1);
            else $fdisplay(passedFile, "%d", 0);

      #10 $finish;

      // close file
      $fclose(passedFile);
   end

   always @(posedge clk) begin : good
       case ({j,k})
           2'b00 :  q2 <= q2;
           2'b01 :  q2 <= 0;
           2'b10 :  q2 <= 1;
           2'b11 :  q2 <= ~q2;
       endcase
   end

   always @(negedge clk) begin
       if (q === q2) begin
           $display($time, " pass q=%b", q);
           //$fdisplay(passedFile, "%d", 1);
       end else begin
           $display($time, " fail q=%b q2=%b", q, q2);
           //$fdisplay(passedFile, "%d", 0);
       end
   end
endmodule

c)

module jk_ff ( input j,
               input k,
               input clk,
               output q);

   reg q;

   always @ (posedge clk)
      case ({j,k})
         2'b00 :  q <= q;
         2'b01 :  q <= 0;
         2'b10 :  q <= 1;
         2'b11 :  q <= ~q;
      endcase
endmodule

Earlier post Testing JK Flipflop using system verilog


texts: How to create a -15v rail from a +15v power supply

texts: I have a +15v power supply rated to 4A, and would like to have a -15v rail that can draw up to 1A.  For the -15v rail would I use a single IC or is there a simple circuit that could accomplish this?


texts: Can repeated UPS failure due overload damage eletronic equipments?

texts:
I had trouble installing a laser print at home that forced me to return to the shop and change it by a new one the next day.
Now, reflecting on the issue, I am in doubt over the cause of the problem.

At first I tried to plug it in the same UPS where the desktop computer is plugged (and where the old deskjet printer was plugged). The device (UPS) simply turned off after some noise and bips everytime I tried. I realized (looking on the internet) that the warm up of a laser printer need a lot of current in the first seconds. It is strange that there is no warning in the documentation of the printer, because I think that it is quite normal to put this type of equipment in a UPS.

When I plugged the (first) printer on a separated socket, it turned on initially, printed one test page, but suddenly starts to blink the LED's in a fashion that indicates, according to the supplier, a failure not possible to be solved by user action. Even after plug out and plug in again the printer was showing the same failure warning.

Before to turn on the replacement printer, I measured some sockets with a voltimeter. They have 3 holes, and most of them have 127 V between live and neutral, but not between live and earth. Except for that one where I plugged the first printer. I was afraid of another damage and plugged it on another socket. It is working normally.

Now: was the printer simply damaged from factory? Maybe the trials in the UPS can have damage it? Is that socket without a dummy earth responsible?


texts: Diode pin labels swapped in this circuit?

texts:
I'm curious why "bl_anode" is shown connected to the "cathode" of the diodes and the two "bl_cat1/2" are shown connected to the anode sides?

Shouldn't the labeling be the opposite? My understanding is the arrow in a diode diagram is the anode and the line the cathode


texts: Parallel L-C circuit powered by an AC generator

texts:
I'm trying to understand how LC resonant circuits work, but no explanation I find on the web helps me with that.

The way I understand it is that if I had only an ideal inductive load, as soon as the voltage was applied on the coil by the generator, the coil would produce a counter EMF that would be almost equal in size but opposite to the applied voltage, reducing in magnitude over time. So the current is limited due to the nature of the coil. We find that current lags behind the applied voltage by 90°.

Now the generator has to constantly push the inductive load that is pushing back. This creates power loss.

But if we connect a capacitor parallel to a coil, the current generated by the coils magnetic field flows into a capacitor instead of pushing back on the generator. After the magnetic field is gone, the capacitor would discharge into the coil. Hence the generator is not having to deal with this reactive power, so total power losses (ignoring power losses in the cables due to the reactive current) are lower. This is only true ofcourse if the capacitor and the coil are able to store the same amount of energy at the operating frequency.

As soon as one is bigger then the other, that additional created emf has to be opposed by the generator, where before it didn't have to deal with it.

This is why if we balance capacitive and inductive effects inside a circuit, we get bigger currents to be used for doing work like in induction heating aparatuses with the same coil resistance and applied voltage.

Is my picture correct?


texts: Modern substitute for BF494 or 2n3707 transistors

texts:
This question has been asked before, here:
https://electronics.stackexchange.com/a/263366/199668
But since it's been almost 5 years since that post, does anyone know any substitutes for the mentioned transistors? I'm attempting to make this circuit:
I can't find these transistors on Amazon, and I don't want to wait 2 weeks for one to arrive elsewhere. Also why are they so hard to find today?


texts: Looking for feedback on switching power supply board design

texts:
I'm currently designing a PCB for my first switching power supply using the LM2576, I've discovered while prototyping that these kinds of circuits are pretty sensitive to layout, rogue inductances and such.
I've had a read of various threads and other resources and tried to avoid making the same mistakes as others, now I'm just wondering if, in the opinion of people more experienced than me, I'm heading in the right direction with my layout or I should start again :')
First layout:

Updated layout:

Schematic:

Inductor: 100uH 5A, https://docs.rs-online.com/a3e0/0900766b81505738.pdf


texts:
If I built a coil like the one in this crystal set.

How could I use a micro to detect which point the alligator clip is on?

Basically I want to use the crystal set as a user interface for an audio playback system.


texts: TDA7379 amp in Double Bridge config draws correct quiescent current but gives no sound

texts:
I'm trying to build the double bridge circuit mentioned in the datasheet, available here: http://lib.chipdip.ru/028/DOC001028540.pdf

There wasn't much information in that document (also it says it's a preliminary version and I couldn't find a newer one), and I couldn't make it work. I tried with two different chips, and after connecting STBY to VCC it starts to consume the correct quiescent current but there is no sound.

The input voltage is 20V, input signal is about 0.7V, and in the diagnostic pin there are 0.1V (which I couldn't find any document on how to interpret).


texts:
I have a question about the 'correct' way to use test benches to test VHDL components in Vivado.
To give you an idea of my task, I have a source file called Top_Level which is going to be the highest level where all other components are created from.
So I have simple register 32-bit register that is created with structural VHDL in the Top_Level file and is made up of the following hierarchy:
Top_Level => 32_bit_Register => 1_bit_Register
Signals are declared in the Top_Level file and are passed down and back through all the components, so my Top_Level file has no inputs or outputs in it's entity.
Now when I go to create a test bench called Top_Level_TB for the Top_Level file I have a problem as I can't port map my Top_Level signals to my Top_Level_TB file as they are not in the entity.
How should I get around this or is this something I shouldn't do? Relatively new to VHDL.
Thanks!


texts: Altium: Script to add all symbols to a schematic?

texts:
Does somebody knows a script which puts all the symbols in a library ([optional]: with every footprint added to it) to a schematic?

Would be handy to look over libraries, but unfortunately Altium don't know Python (yet).


texts:
I'm looking into the design of the control circuit for the mosfet. If I know the output voltage and input voltage then I can find the duty cycle required. I found this schematic that uses feedback

Source

https://www.maximintegrated.com/en/app-notes/index.mvp/id/2031

Why would I need feedback that changes the duty cycle like above ?, if the output voltage is dependent on the duty cycle and Vin and if those are fixed values then Vout should be constant regardless of load ?, also I'm a bit confused on the working of the above schematic, is it trying to maintain Verror of 0V regardless of changes in Vout ?


texts: Is a scheme like the one below better than the one listed above for meeting USB eye diagram specs for USB full speed? I'd imagine that ditching the capacitors would be a good idea.


texts: Schematics: where do I need to place a junction?

texts:
I'm a bit confused about where I need to place a junction on the schematic, and where I don't. For example:

When I connect a part, like a resistor or cap, to a wire, do I need to add a junction point?
What if I connect two wires together?
What if I connect two parts together directly?

My schematic is below. I've just let KiCad do the work for me, but I'm not really sure if my wires are really being connected as they should. I currently only have one junction - attached to pin 19.


texts: I'm trying to understand electricity better, but all I found was those stupid water pipe analogies. Can you explain it to me in terms of actual electricity? What is voltage, the speed of the electrons flowing through the wire? Somehow this makes little sense to me but I don't know. Is amperage then just the "flow through", how many electrons pass through? Where does the energy of the electrons come in, if at all? Thankyou!


texts: How do I read the dimensions to create a PCB footprint?

texts:
I'm trying to make a PCB footprint for the SSD1306 ribbon strip, and am unsure of the correct dimensions for the solder pads. The horizontal dimensions are clear enough but I don't know where the pads start and finish vertically speaking.

And also what does the "LS" refer to in the red circle?

Guidance is greatly appreciated!


texts: What is the purpose of these P+ and P- connections?

texts:
I took apart my LED light fixture to clean its diffuser, when I noticed something odd:

As you can see, it has a DC power source connected to 4 daisy chained circuits. I expected that these 4 circuit boards to be connected in parallel, with the daisy chaining forming a shared + and - bus.

However, there are these P- contacts connected to P+, and  I cant figure out what they're for.

Any ideas?

Edit:

I've laid out the traces of the first two boards. It appears that the first two boards form a pair, with 2 current paths.

The green current path goes between the + and - connections of the first board, passing 11 LEDs along the way.
The magenta current path passes from - through 6 (only 5 are numbered on the picture, I missed one) LEDs, to P-, then from P- through all 16 LEDs of the second board.
The cyan indicates the etched portions of the board.
The red and black are the power rails, chained straight through the boards.


texts: Why are the E-series numbers different from the powers of 10?

texts:
The E-series numbers are the common values used in resistors.  For example, the E6 values are:

1.0
1.5
2.2
3.3
4.7
6.8

As you can see, each is about \$10^\frac16\$ apart.  But I wonder why they aren't the powers of \$10^\frac16\$ rounded to 2 significant figures.

\$10^\frac16 \approx 1.4678\$
\$10^\frac26 \approx 2.1544\$
\$10^\frac36 \approx 3.1623\$
\$10^\frac46 \approx 4.6416\$
\$10^\frac56 \approx 6.8129\$

3.1623 should't round to 3.3 no matter rounding upwards or downwards.  And by rounding to the closest number, 4.6416 rounds to 4.6.

The same happens in other E-series values.  For example, the powers of \$10^\frac{1}{12}\$ rounded to 2 significant figures are:

\$10^\frac{0}{12} \approx 1.0\$
\$10^\frac{1}{12} \approx 1.2\$
\$10^\frac{2}{12} \approx 1.5\$
\$10^\frac{3}{12} \approx 1.8\$
\$10^\frac{4}{12} \approx 2.2\$
\$10^\frac{5}{12} \approx 2.6\$
\$10^\frac{6}{12} \approx 3.2\$
\$10^\frac{7}{12} \approx 3.8\$
\$10^\frac{8}{12} \approx 4.6\$
\$10^\frac{9}{12} \approx 5.6\$
\$10^\frac{10}{12} \approx 6.8\$
\$10^\frac{11}{12} \approx 8.3\$

While the E12 values are:

1.0
1.2
1.5
1.8
2.2
2.7
3.3
3.9
4.7
5.6
6.8
8.2

The numbers 2.7, 3.3, 3.9, 4.7, and 8.2 from E12 are different from their corresponding ones computed above.

So why are the E-series of preferred numbers different from the powers of 10 rounded to the closest number?


texts: Couldn't read the correct values of DS1302 RTC Registers

texts:
I am trying to read register values of DS1302 RTC using a PIC MCU in proteus environment. I have made two simple functions for that purpose, one is for the transfer of DATA to the RTC and other is for receiving from it.

I can only get the correct value of seconds register but all other values (min, days, months etc) are either 0xFF or 0x00. Couldn't find where the problem lies.

I have been tracking the bytes transfer to the RTC using an OSCILLOSCOPE which shows that the data is correctly transferring on the RISING EDGE of the clock. I am not initializing RTC values (because the RTC won't LATCH my data) so I initialize it to the system calendar (option available in proteus).

Here I am sending the address of the second's register (0x81) and receiving the second's value (correct value) from RTC.

Here I am sending the value of minutes and getting (0xFF) everytime.

And for Hour register, I get 0x00. For DATE register I get 0xFF and vice versa.

Here are the two functions through which I am sending and receiving data.

char value=0x00;

void SPI_SEND_DATA(char ADDRESS,char DATA){
           delay_us(1);
           EN=1;
           SSPBUF = ADDRESS;            // Transmit ADDRESS
           while(!SPI_BUSY_FLAG);
           value=SSPBUF;               // Clear Bit flag
           SSPBUF = DATA;              // Transmit DATA
           while(!SPI_BUSY_FLAG);
           value=SSPBUF;               // Clear BF flag
           EN=0;
}

char SPI_RCV_DATA(char ADDRESS){
            delay_us(1);
            EN=1;
            SSPBUF = ADDRESS;
            while(!SPI_BUSY_FLAG);
            value=SSPBUF;               // Clear Bit flag
            SSPBUF=0x00;                // Start the SCLK
            while(!SPI_BUSY_FLAG);      // Recieve data
            value=SSPBUF;               // Store the recieved Byte
            EN=0;                       // Fininsh Reading
            return value;
}

Here is how I am initializing the clock in proteus automatically and the clock ticks quite fine.

I have also attached the  full project code and simulation file of proteus, in case anyone want to try it. Kindly find in the attachment herewith.
Full Project files

Any help/suggestion would be appreciated.

EDIT: I tried the same code on MAX6902 [the only thing I changed is; I have inverted the ENABLE pin because according to the MAX6902 datasheet, its active low] and it worked like charm. The thing is, proteus may have some problem in simulating DS1302.


texts:
I've got an accelerometer connected to a PIC24FJ family controller via SPI.  I'm trying the simplest operation--reading an ID register whose contents never change--to confirm that I can make it work.  While the problem could be due to one of many things, I'm working with the SPI peripheral for the first time and code generated by MCC.

What I'm wondering is, in an 8-bit transfer, does it generate 8 clocks to send the register request, followed by 8 more clocks to read the reply?  Or do I have to get the reply byte separately?  I've looked at both the datasheet for the processor as well as the Family datasheet, and neither seems to show this.  There are plenty of pictures of waveforms for audio streams, and slave operation but I couldn't find something this simple.  There is an illustration of an 8-bit transfer, but no suggestion as to what happens after the first 8 bits go out.

As for the peripheral, you put something to the transmit register, wait for a ready bit, and go pick up your results from the receive register.  Since they don't explain what happens, that makes it magic.  When I read the source code, I end up in the same place.  Stuff the register, pick up results from the other register.  I could look up other processors, but I couldn't be confident that the peripheral works the same way.

I haven't put a 'scope on it yet, because it's a BGA chip, and the PIC is a pretty find pitch.  It may come to that anyway, but there's a chance someone could help if in fact there's something I don't understand about the transfer process.

. . .

Bonus question: What data do you clock out when you are just trying to read a byte from the chip? In this case, writing all zeroes would be a write request to a register you're not supposed to access.  So there's got to be a better answer.


texts: Why can a switched-mode-power-supply be dammaged without load?

texts:
I've read that some SMPSs can be damaged if they are being operated without any load (or under a specified current). What is the actual cause of this? What is happening if it is damaged due to this?

Does OVP/UVP/OCP/CSP (etc) protect from damage due to no/low load? I've seen some ATX PSU have these protections (however none of them seem to have a specified minimal load).

How do (modern) mobile chargers and other (similar) consumer products cope with this problem? After all one may expect to be able to just plug in it to the power outlet without destroying it.


texts: Filtering inductor for power electronic converter design formula

texts:
I have following power electronic converter

and I need to determine inductance of the filtering chokes. I have deduced following formula $$L=\frac{V_{dc}\cdot(1-d)}{f_s\cdot\Delta i_L}$$ (based on \$v=L\frac{di}{dt}\$), where \$V_{dc}\$ is dc link voltage, \$f_s\$ is switching frequency (=12 kHz), \$\Delta i_L\$ is desired current ripple and \$d\$ is duty ratio (\$0\leq d\leq1\$). My problem is that I would like to use Sinewave Pulse Width Modulation so the duty ratio is changing sinusoidally. I don't know what value to substitute. The solution could be to choose the worst case but I don't know what value of \$d\$ coresponds to the worst case. Can anybody give me an advice how to solve that? Thanks in advance.


texts: Are FPGA's as powerful as the number of gates they have?

texts:
Let's say I have a 1 million gate FPGA. I've found a few processors on OpenCores which only require 50k gates. So would it be possible to make, say, an 8 core processor with such an FPGA? Or are there limits to FPGAs when it comes to implementing massively parallel things?

Sorry if it sounds newbish, but I am a newb to FPGAs.


texts:
In the question, why couldn't I just find Line current from Line Voltage?

Is not Line Current=Line Voltage/Impedance?

I know line voltage and line current aren't in phase, that the angle between line voltage and line current is 30 + theta, where theta is the angle current is lagging by.

But

How do I find theta?
How do I utilise it once I've found it out?

I'm really only lookin for an alternative solution to the question


texts:
I have salvaged a lithium-ion battery pack from a laptop.On the case,it is written each battery has 3.7v(they are 18650s),but when I measured using my multimeter I found each battery to be just 2.8v(some were 3.1v and 3.0v).
My question is,that is it safe to charge these batteries using normal lithium ion battery chargers(TP4056)?
Any answer will be of nice help!


texts:
I'm currently in my second year of computer engineering. I've taken circuit analysis courses and have a good general understanding of components, and a little bit of digital design, however, I'm very confused on how one actually goes about designing circuits to complete a task. For example, what if I wanted to make a circuit that would be used for some sort of door-lock that takes a 4-digit combination (inputted through a 10-digit number pad) along with a physical key to open the door - how would one design something like this?

Thoughts that come to my head:

I suppose the easy part would be the physical key and hardware

this would include the actual key and lock mechanism

Now, what I'm very curious about is the actual circuit that controls the 4-digit combination

(correct me if I'm wrong) there  has to be touch sensors within the keypad that has values for all numbers 0-9
of course, this circuit will have resistors, sensors, voltage source, etc
Some processing must happen to determine whether or not the 4 digits entered are correct or not

More specifically, my question is (are): What is the thought process behind designing this circuit? How does one choose the correct components? How do you create a schematic through reverse-analysis (essentially synthesis)? Not all of these have to be answered, but I just want a general understanding. I'm curious as I'd like to begin creating circuits that do certain things, but I'm lost on how to think about them.


texts: 8 bit barrel shifter using 2 x 1 MUX in VHDL

texts:
Is it possible to write a VHDL code to exactly follow this diagram?
I have written some codes before using subcircuits to form a larger circuit (for example 8 bit comparator using 1 bit comparators) and I'm wondering if I can do something similar here. Maybe use 2x1 MUX as a subcircuit or a component and go from there on?


texts: Modelling effects of unbuffered library characterization cell outputs on timing constraint tables

texts:
Can someone explain to me or point me to a resource that will shed some light on how (instead of using a buffered library cell, we use a unbuffered library cell) including the effects of unbuffered outputs (output drive current) will affect hold/setup/min_pulse_width constraint times?

To give context of buffering - in a purely digital cell for a NAND gate, 2 inverters are added to the output of the NAND gate which is a buffered cell. Remove the 2 inverters will result in the output current of the NAND gate to be dependent on the input logic combinations.

I understand how the output load can be used to model unbuffered outputs but I'm wondering how does this affect the setup/hold/min_pulse_width constraint times?

I haven't been able to find my resources about load dependency on constraint table, so any help will be greatly appreciated :)


texts: Replacing capacitors in a power supply circuit

texts:
Recently, my computer monitor has stopped turning on, I think this could be down to a few faulty capacitors... I think. I tested the output of the power circuit and the outputs, 12v and 5v, were working, when I added some load (using a 4.4Ω resistor) the 5v line died.

I removed all the capacitors from the PCB and tested them with a multimeter set to measure resistance. I can watch the capacitors charge; they all look fine though (I'm not sure if there's a better way to test them than this though?).

I still thought that it could be a problem with a few capacitors as they looked like they had slight bulges in the tops, so I found a capacitor from an old computer PSU that matched the spec (1000µf 25v) and tried my monitor with this... success. However this morning, the monitor has stopped working again, so I'm going to just replace all of the capacitors and see if that resolves the issue.

I've just started looking for capacitors online to replace all of the ones on the power supply board, however there are so many different types. I'm looking on uk.rs-online.com, but say I've searched for 1000µf 25v electrolytic capacitors, loads of different ones are returned at varying prices, does it matter which one I choose? Some of them are labelled 25v dc, could you explain what the difference between a capacitor labelled 25v and one labelled 25v dc are? Are there other things I need to take into consideration when buying these capacitors other than voltage and capacitance?

Here is the power supply board that is faulty:

A close up of a couple of the capacitors:


texts:
I have been using USART for interfacing  PICs to my PC for datalogging. The problem is that now serial ports are not very common and often you need a USB-Serial adapters which do not always work or have problems with drivers. I'm not a big fan of USB but I'm thinking of trying the USB-UART chip form Micrchip MCP2200-I/SO.

In your experience what is the most reliable and universal way of interfacing the PIC-embedded world to the PC/network enabled world!


texts: Is the exam exercise in contradiction with itself?

texts:
For the DC circuit below, \$E_1=15V\$, \$R_1=R_2=4k\Omega\$, \$R_3=1k\Omega\$ and \$R_4+R_5=3k\Omega\$. When switch \$P\$ is open, the voltmeter (with internal resistance \$R_v=10k\Omega\$) reads the voltage \$U_{21}=15V\$. Find the current \$I\$ through resistor \$R_3\$ when switch \$P\$ is closed, if, in that case (closed switch), the voltmeter reads \$20V\$.

What I did to solve this is find \$I_g\$ and \$R_6\$ in the first state (when \$P\$ is open) and then find the current \$I\$ using superposition of currents from sources \$E_1\$, \$E_2\$ and \$I_g\$) in the second state (when \$P\$ is closed). But I got a wrong result.
Then I got really confused by the voltmeter readings. If the voltmeter shows \$15V\$ when switch \$P\$ is open, that means that \$-I_gR_6=15V\$, but in the second state, when \$P\$ is closed, we have \$-I_gR_6=20V\$. How can that be?


texts: 3 transistors connected in series principle?

texts: My teacher asked me what is the principle behind this circuit, And i don't know what does he means, what are your thoughts ?.


texts:
I'm working on lighting up an entire LEGO city from my nephew. But the problem is I need a lot of leds with different amperes and voltages ( I'm gonna put them in parallel). So my 2 questions are :

Do I need to put a resistor before every led? or can I just put a resistor in front of a bunch of leds ( I have around 15-25 leds per resistor)?
I need for most of my leds about the same value of the resistor (around 150 Ohms). Can I put the resistor of exact 150 Ohms (1% tolerance) in front of the leds? or do I need to set the value a little bit higher with an extra resistor?

EDIT: also in the comments: 41 yellow and red leds have 2 volts and 20mA
About 30 white leds have 3.5 volts and 20mA and about 10-20 leds have 2.6 volts and 70mA


texts: What is the direction of current flowing through the primary coil and secondary coil of a transformer?

texts:
I am very much confused about the direction of the induced current in the secondary coil in a transformer. I am sharing a video tutorial. Please help me understand this. To see the video click here.

In this video between 36:25 min - 37:28 min they are showing current flowing through a transformer. According to the statements between 32:50 min - 36:24 min, I think the direction of the current flowing through the secondary coil as shown should be in the reverse direction.

I think if the direction of current flow is in--

primary coil     -------     secondary coil

  clockwise         ------      anti_clockwise
  anti_clockwise    ------       clockwise

but...in the video --

primary coil     -------     secondary coil

  clockwise         ------      clockwise
  anti_clockwise    ------      anti_clockwise

Why?


texts:
I am using a 310VDC,  4pole BLDC motor with hall sensor feedback for my application.
My objective is to run the BLDC motor at 7500 rpm. My motor rated speed is 8500rpm.
I am able to run motor at 7500 rpm now.
My other objective is to stop the motor within 1 second period from 7500 rpm.
I am using BLDC drive as my own design.
Now I am able to stop motor within 5 seconds.
I am not able to reduce the above stopping time.
Help me with the methodology to stop within one second period.
Input supply of my BLDC drive is 310V.


texts: What should I consider before purchasing a professional Pick and Place machine?

texts:
I am thinking to expand business and go with a professional pick and place machine. Not the most expensive, but not the cheaper ones.

I will ask about software licenses/usage, training and post sales support, cost of repairs, and hidden costs. Is there anything else I'm missing?

I am already shipping dozens of boards per week, and I want to expand. I would rewrite the question as: if you are the CTO of a small assembly company, and your boss ask you to buy a pick and place, what is the most critical factor to take into consideration?


texts: Data over DC Power, mono-directional, simplest circuit

texts:
(To preface, I will probably just run 4 wires, with RS485 on 2 and power on the others, but this came to my head, and I started thinking about it.)

I was thinking of a simple way to send simple low speed data (9600 baud?), from a single source out to multiple devices using just the two wires also used to power the devices.  No return data is needed.

Situation:  12 or 24 volt system of perhaps 40 'nodes' spread over a 200 foot x 200 foot area, each 'node' is a simple microprocessor with it's own software address, running a few RGB LEDs. Harsh environment, only has to last 2 weeks (Burning Man).  The data would be simple commands, with no more that say 8 bytes per command (with address, checksum etc.)  Data would be sent from a central controller that simply coordinates the colors and timing etc of the LEDs.  Devices will be added in a 'star' pattern, but with multiple nodes on each line.  Each node will run a processor at 5 volts, and perhaps 300 mA of 12 volts for the LEDs at each node.

My thought was if I use a power supply between 16 to 24 volts (24 volts is easy to find) and at each node used a 12 volt regulator for the LEDs, and a 5 volt regulator for the processor, that would prevent voltage drop problems with long lines.  If, at the power supply, I put 3 or more high current diodes in series, then my 24 volt supply becomes more like 22 or less.  By putting an FET parallel to the diodes, I could now switch the power line from 22 to 24 volts.  With the appropriate driver, a microprocessor (5 volt) serial TX line could 'modulate' the voltage.

At each node, I could have a single supply comparator on the 5 volt supply, with resistor voltage divider off of the 22 volt modulated line as the input to the comparator, with it's output feeding into the processor RX line for serial data.  In an ideal situation, a simple low pass filter and voltage divider could provide the reference for the comparator, in actuality, the 22 volt supply will probably vary a bit, maybe not enough to worry about, and perhaps I just use a lot of diodes to make more of a voltage difference, so that the reference is guaranteed to fall inside the voltage drop range.

Any thoughts?  Does this seem doable.  Since the data is just broadcast out, with no need to get a response, this seemed the simplest way to go.


texts: Why am I getting NaN and INF values for my Norton Equivalent Circuit

texts:
I am given this question

I have 2 questions:

1) Is my work wrong? I am assuming so since I am getting some funky answers. If I am wrong, will you please point out what I should have done differently?

2) Since he didn't add a ground I figured I would have to consider the entire bottom wire as + 0.2I_0 because of the dependent source, but would I also have to consider my external voltage (V_x) in some way? If so, how would I add it into my work?

Problems I had with this question:

1) There is no ground, I am not familiar with problems like this.

2) I was not sure what equations I needed for all my unknowns. The equation that feels most like it doesn't belong is Equation 2, but I could not find any better approach.

Thanks!

Here is my attempt to solve for R_th:


texts: What's the math behind generators with electromagnet cores?

texts: Our biggest generators spin an electromagnet to produce current. Why does it take less electricity to maintain the electromagnet than the electromagnet generates? In an ideal world, how much power would it take to maintain the electromagnet?


texts: What should I use to make this MOSFET drop the gate-voltage even faster?

texts:
I'm trying to create a delay circuit like this.
When I snapp on the push button, then the current flows from +3.3V to GND and bypass the 220 Ohm resistor, which is my load.
But the problem here is that I want to have this current peaks like a square wave, PWM etc, not this slow slope.
Question:
What should I replace so this MOSFET got its voltage gate dropped to 0V when the gate voltag is under a certain threshold?
I will NOT use a mechanical relay and optocoupler will not work neither.
Digital circuits will work too. But I'm not expert at them.

Solution:
Schmitt-trigger


texts: What property of a BJT transistor makes it an amplifier?

texts:
I know how we can amplify a given signal using BJT transistors by biasing them. But I would like to know what is that crux property which enables BJT transistor to act like an amplifier. Is it the constant nature of reverse saturation current or is it the definite relationship between the base and the collector current or anything else?

I am specifically talking about the BJT.


texts:
If using the nodal analysis for a certain circuit one usually chooses a node as reference node such that one can reach as many other nodes as possible. Unfortunately 99% of the literature I found on this subject seems to assume that one can alway find such a node that reaches every other node within a single branch.

Consider the following example:

One can see that obviously it's not possible to reach every node within a single branch, even if we change the reference node.

My text book states that one would need to use a super node in such a situation, as also shown in the example with node #4.

I assume this is due to our equations not being linear independent if we would consider #4 a "normal" node.

Please provide me some insight in why we have to use a super node here and if my assumption is correct. I'd highly appreciate to see some kind of mathematical proof.


texts: Quartus synthesises memory in logic despite verilog synthesis attribute

texts:
I have the following read-only memory module:

import Signals::*;

module ProgramMemory(input logic [PC_SIZE:0]  pc,
              output logic [IS:0] ir
);

    (* romstyle = "M10K" *) logic [IS:0] memory [MEM_SIZE:0];

   initial
     $readmemb("program.mem", memory);

   assign ir = memory[pc];

endmodule // ProgramMemory

When it is synthesized for a Cyclone V the ROM is implemented in logic rather than dedicated read-only memory. How can I make this work?

I've turned of the minimum ROM and RAM sizes in the project settings.

IS = 10,
MEM_SIZE = 10


texts:
I'm writing code that sends SCPI commands to various instruments (power supplies, o'scopes, data acquisition, etc.)
The TDK Lambda power supply is returning the code "C01" which means "Illegal command or query".
Are there standard error codes or are the error codes manufacturing / instrument specific?


texts: Generic method for implementing if-else statement in hardware (using gates,mux-demux,flip flops ) etc

texts:
I am currently working on converting a high level language into an equivalent circuit.. I am able to convert simple expressions like a+b, a.b or a combination of them using gates. But I wanted to know if there's a generic method to implement if-else statement using electronic components such as gates, mux, ff. A simple answer would be to use mux-demux. But that wouldn't solve the following problem(for example)

if(posedge(clock)):

q<=d

The construct for that would be positive edge triggered flip flop. So is there any general way to implement if-else statement?

Any help would be appreciated. Thanks!


texts: Rectified X2 circuit gives 2 voltages depending on how the powerplug is connected to the wall (EU)

texts:
simulate this circuit – Schematic created using CircuitLab

I'm trying to control a mosfet directly from a phase shifted 50Hz sine wave. But when I was trying to understand the voltage drop with X2 capacitors something weird happend.

Depending on how I plug the power plug in the wall the voltage measured at the arrows changes. It measures 3.5VDC or 8.5 ~ 9 VDC when the power plug is turned 180 degrees.

This phenomenon also happens when the second (or first) X2 capacitor is removed.

Can someone explain why this is happening?

Edit: control tests:

used 10 different x2 capacitors
used 4 different full bridge rectifiers which each gave the full 331VDC output when all X2 capacitors were removed

Edit: Ground connection:

the ground is connected to the full bridge rectifier.


texts: What kind of component is this? And is that crack normal or is it a sign that it's bad?


texts: Connecting push button to microcontroller

texts:
I want to connect a simple push button to a microcontroller and record the time I press the button. Would this work or do I need to put a resistor in between?
If yes why?


texts: Do Atmega328 chips have pseudo-unique IDs?

texts: I'd like a couple of Atmega328s to run the same program, but they're going to interface with each other and need unique IDs. Is there any such ID or serial number hard-coded on the chip?


texts: What type of connector to use for pressure contact?

texts:
I'm designing a robot gripper that needs to pickup an electronic device (the size of half a laptop) and move it around. The problem is that when the device gets picked up, I need to establish a USB connection (the device has one of those small USB connectors.

I was thinking about designing a PCB with an SMD right angle USB connector in one side and a few fat pads on the other. I would manually attach the connector to the device before the robot picks it up, and I would have some sort of spring on the gripper to make the USB connection. Something like the ones used in the SD cards, but bigger.

Question is: do you have another suggestion or know what component to use to make the electrical contact?


texts: Input Output Relationship of Inverting amplifier

texts: Can someone explain the input output relationship of below attached image ?


texts:
Given the transfer function for a given filter, how can I find a value for the q-factor?

For example, I have this transfer function for a Sallen-Key lowpass filter

\$ H(s) = \dfrac{1}{R_1R_2C_1C_2s^2 + (R_1C_2 + R_2C_2)s + 1} \$

And I also have my component values. Now I've seen formulas for calculate Q from component values, but where do the formulas come from? Is there a way of finding Q from any transfer function?


texts:
I'm builing a 48v DC LED system to be used inside a fountain in a public space. I'm using a 48DC 30A switching power supply.

What should I do to make it safe in case any conductor gets exposed to the water?

Should I ground the DC- output?


texts: I am working on a hobby project that I want to power with a LiPo Cell battery which provides 3.7v with a max of 2A output. I need to power a 5v peripheral that has varying current draw up to the 1A-1.2A range. In this case it seems I could use a TPS61200 switching regulator or a TPS61090. I am leaning toward the latter because I could really use 96% efficiency (vs 90% on the TPS61200) and the low battery indication, but I was wondering if there was any reason to use the TPS61200 in this case?


texts: Is it possible to build a grid of silicon photosites to build a digital camera at home?

texts: So I know a digital camera takes light and focuses it via the lens onto a sensor made out of silicon. It is made up of a grid of tiny photosites that are sensitive to light. Each photosite is usually called a pixel, a contraction of "picture element". I was wondering, even if it is as small as 100x100 pixels or even smaller, is it possible to build my own grid of tiny photosites at home out of silicon and use that to make a digital camera? I know you can go out and buy them but I am trying not to use premade parts for this project only raw materials, machinery and other thing(transistors, diodes, resistors etc.) Is it possible to build one of these silicon grids at home? If so how?


texts: Temperature vs. lifespan: the 10 degrees Celsius 'rule'

texts:
TL;DR: What's the origin of the 10 degrees Celsius rule?

I have heard many times that for every 10 degrees Celsius, the lifespan of components gets halved. There are many documents on the web quoting that number.

But it seems too general to be taken at face value.

When I try to find literature on the topic, I come up with two things:

it's either too complex for me to understand.
it's written by someone that understands as much, or less, than me.
or, mostly, it's summed up as: high temperatures are bad, buy our solution.

I believe that the truth is probably a lot more complex:

components have different temperature profiles with their own MTBF.
temperature cycles have to have an impact, at least at the mechanical level.

I am trying to answer this question:

If we average all consumer electronics:

does the 10 degrees Celsius rule have any validity
or, was it always false / without basis
or, was it valid a long time ago but not relevant anymore
or, was it based on observations in a specific context
or... any other scenario


texts:
I have been trying to implement a Vending Machine where the user selects P(2to0)
P(2) : 3.5 Currency_X
P(1) : 3 Currency_X
P(0) : 2.5 Currency_X
C(3 to 0) as coins
5 Currency_X / 2 Currency_X / 1 Currency_X / 0.5 Currency_X.
And it gives the money back (R2to0) (2,1,0.5) and the item.
My code seems to not go the next state (S2) which returns the money back.

    entity Vending_Machine is
    Port ( C : in  STD_LOGIC_VECTOR (3 downto 0);
           P : in  STD_LOGIC_VECTOR (2 downto 0);
           CLK : in  STD_LOGIC;
           Reset : in  STD_LOGIC;
           R : out  STD_LOGIC_VECTOR (2 downto 0);
           Vend : out  STD_LOGIC_VECTOR (2 downto 0));
end Vending_Machine;

architecture Behavioral of Vending_Machine is
    type STATE_TYPE is (S0,S1,S2,S3);
    signal CurrentState,NextState:STATE_TYPE;

begin
            --CLK and Reset Process
        process (CLK, Reset)
        begin
                if (Reset = '1') then
                        CurrentState <= S0;
                elsif (CLK 'Event and CLK = '1') then
                        CurrentState <= NextState;
                end if;
                end process;

                --Vending Machine Process
        process (CurrentState,P(0),P(1),P(2),C(0),C(1),C(2), C(3))
            Variable Sum , Price, Product, Change : INTEGER;
            begin

        case CurrentState is
            when S0=>                           --Will check which product is selected
                    R <="000";
                    Vend<="000";
                if ( P(0)= '1' ) then
                    Price := 5;                 --Due to Errors in REAL We changed to INT
                    Product := 1;
                    Sum := 0;
                    NextState <= S1;
                end if;
                if ( P(1) = '1' ) then
                    Price := 6;
                    Product := 2;
                    Sum := 0;
                    NextState <= S1;
                end if;
                if ( P(2) = '1' ) then
                    Price := 7;
                    Product := 3;
                    Sum := 0;
                    NextState <= S1;
                end if;
            when S1=>
                if(C(0) = '1') then
                    Sum := Sum + 1;
                elsif(C(1) = '1') then
                    Sum := Sum + 2;
                elsif(C(2) = '1') then
                    Sum := Sum + 4;
                elsif(C(3) = '1') then
                    Sum := Sum + 10;
                end if;
                if(Price > Sum) then
                    NextState <= S1;
                elsif (Price <= Sum) then
                    Change := Sum - Price;
                    NextState <= S2;
                end if;
                                                        -- Change Possibilites, 1 / 2 / 4.
            when S2=>
                if ( Change >= 4 ) then
                    R<="100";
                    Change:=Change -4;
                elsif( Change >= 2) then
                    R<= "010";
                    Change:=Change-2;
                elsif(Change >= 1) then
                    R<="001";
                    Change:=Change-1;
                end if;
                if(Change > 0 ) then
                    NextState <= S2;
                elsif (Change = 0) then
                    NextState <=S3;
                end if;
            When S3=>
                if ( Product = 1) then
                    Vend <= "001";
                elsif(Product = 2) then
                    Vend <= "010";
                elsif (Product = 3) then
                    Vend <= "100";
                end if;
                    NextState <= S0;
            end case;end process;end Behavioral;
```


texts: As a school project I was wiring up an IR LED in series with a biasing resist. I was using a breadboard and a vex cortex controller. I understand that a resistor is important because it prevents the LED from receiving to much current and burning out, but why do they use a biased resistor rather than a normal resistor?


texts: What's the purpose of using PNP transistors on I2S bus?

texts: What could be the reason of using these 3 PNP transistors on I2S bus (LRCK, BCK and DATA pins)? The DAC used in this schematic is PCM5102. I know for sure that this DAC would work without these transistors, so I just wanted to check with you and find the real purpose of them in this particular schematic.


texts: What's the difference between 24AA1025, 24FC1025 and 24LC1025

texts:
24AA1025: operates from 1.7V - 5.5V, 400kHz, $2.37

24FC1025: operates from 2.5V - 5.5V, 1 MHz, $2.37

24LC1025: operates from 2.5V - 5.5V, 400kHz, $2.37

See here.

24AA1025 is unique, because of the lower operating range. What I don't understand is why Microchip produce both 24FC1025 and 24LC1025 at the same price with different maximum clock frequencies. Why not just make one? Am I missing something?


texts: Is it possible to design a 2:1 multiplexer using only inverters, XOR gates, half adders and full adders? If so how?

texts:
One of my final exam questions in digital design was to design a circuit that converts an 8-bit Sign/Magnitude number to Two's Complement number using only inverters, XOR gates, half adders and full adders. The simplest approach to this problem, I thought, was to use a multiplexer. However, I couldn't design one using the allowed components. Is it even possible to make a MUX out of these components or does this problem require a different approach?

Edit:

If I could make a multiplexer, my solution would be to multiplex the input number and a version of it that is inverted and added 1 using the sign bit as select.


texts: Relationship between electric field at aperture and field at distance

texts:
I'm new to this forum and turned here because I have no other help to turn to. In studying antenna  theory and I came across the relationship between E0(Electric field at aperture) and Er(Electric field at distance r). It was stated as follows:

$$ |Er| = \frac { |E_0| \times A } { r \times \lambda } $$ where:

\$ Er \$ is the electric field broadside to aperture at distance \$ r \$,

\$ E_0 \$ the electric field at aperture,

\$ A \$ the effective aperture of the antenna,

\$ r \$ the distance between the two fields,

\$ \lambda \$ the of radiating filed wave length.

I have tried extensively to find proof to this either mathematically or intuitively but I am really confused, specially how lambda makes an effect on the field intensity change. My only idea is that as r increases, the field varies according to inverse square law which I believe is a very basic view than what is expected.

Any help will be appreciated, or links to sources where I can research myself.


texts: What can happen if I try to charge lead acid battery outside charger's capacity range?

texts:
I'm looking for lead acid battery charger. My battery (originally from UPS) has 12V and about 40Ah capacity. This is what I see in one charger's datasheet:

  Automatic charger for sealed lead acid batteries 2 V up to 24 V with the capacity range from 2.4
  Ah to 24 Ah.

Actual capacity of my battery is definitelly lower than what it says on the seal, but still it's clearly out of range. Is that actually problem? If so, why?