texts:
I am currently designing a battery powered LED project, that will be charged and/or operated over 25W PoE+. In my current design, I am using a flyback converter to convert the 48V to 12V and for establishing galvanic isolation. For optimisation purposes, I would really like to kick out that chunky and expensive flyback transformer and replace it by a non isolated DC/DC converter. However, in all >25W PoE PD reference designs I saw from IC manufacturers, they are always using isolated converters.

My product has a plastic housing and is not grounded nor is it further connected to any other device that is grounded. Only in case of mechanical damage (e.g. housing cracked open) will the 48V be exposed to the environment.

Another issue could be my onboard battery charger IC, which bucks the 12V from the PoE flyback converter output further down to charge a 2S Li-Ion Pack. The IC has a max input voltage of 24V, so in case of failure of a non isolated DC/DC, 48V will be applied to charger IC and damage it.

I already read another post about isolated vs non isolated PoE but I did not come to a conclusion for my project.

Is there anything I missed why an isolated PoE converter would still be necessary or the better choice for my application?
If yes, could you please give an example for this failure case?
I have not seen any standard that PoE with higher power requires galvanic isolation. Am I wrong about that?


texts: Period of one oscillation of a PWM signal at 4Mhz and a counter

texts:
Say I have a counter that increments with a 4MHz clock. Would the period of a single oscillation of the PWM signal be: $${1\over{4\times{10^6}}}=2.5\times10^{-7}s$$

The reason I ask this is because of the context. I haven't had any other questions like this before and I can't find anything about it in my textbook.

I think this is correct since I would assume it would be very small (which the period is).

Thanks for any clarification.


texts: How does the RC time constant affect behavior of a passive integrator/differentiator?

texts:
I'm reading the first chapter of the AoE. I've come across this section on differentiator/integrator circuits and couldn't understand the math behind it.

For the first picture, it says small RC means dV/dt being much lower than dVin/dt, but I don't understand how it does this. Similarly, I'm not sure how large RC means Vin >> V. I know this may be a petty question, so please be patient with me.


texts: Last night I was uploading a program on arduino and while the process was in way I mistakenly plugged out the usb cable from the PC. Today when I plugged the arduino to PC its voltage regulator start getting hot but the power led's are not blinking and the board is like dead


texts: Is it possible to generate a list of all Net names in Altium Designer

texts: If I have a schematics in Altium Designer and it is spread over 10 sheets then is it possible to generate a list of all net names that are used in it? How can I generate this list? I want to do this to double check if a certain Net name is miss-spelled at one or more places in any sheet.


texts: Is this parallel resonant circuit problem fully constrained?

texts:
Is there a single answer to the following question?

Design a band-pass filter using a parallel resonant circuit to meet the following specifications: \$BW=500Hz, Q=40, I_{C_{max}}=20mA, V_{C_{max}}=2.5V\$.

Full disclosure: this is question 35 on page 655 of Pearson's Electronics Fundamentals 8th Ed.

I posit the following circuit:

simulate this circuit – Schematic created using CircuitLab

I deduce that: \$f_r = 20kHz\$ because \$f_r = Q . BW\$, \$V_{in} = 2.5V\$ since at resonance the \$LC\$ tank will have infinite impedance and therefore all the input voltage, and therefore \$R = \frac{V_{in}}{20mA} = 125 \Omega\$.

Next I conclude that \$LC = \frac{1}{(2 \pi f_r)^2}\$ from the standard formula \$f_r = \frac{1}{2\pi\sqrt{LC}}\$.

The book gives \$L = 989\mu H, C = 0.064\mu F\$, which satisfies this, but I don't see how they got specific values of \$L\$ and \$C\$.


texts:
I am using LM324N as a comparator which has Reference voltage of 1.2V to +ve terminal. It requires supply voltage VCC=24V & VEE=Gnd.When input is 0V Vout=24 and when input= above reference voltage Vout=24v.

The problem is that

IC is getting over heated and burning at VCC and Gnd pin.


texts:
I'm attempting to make a 12v blinking light that turns off with a high signal and since I've got some 5v arduino pro minis I though I might do it with them. So I put together a program and a plan

My idea was, that when the switch is closed, 3-4.6v is applied to pin 3 (logic level high) and my program stops the blinking.
Testing this with 5v without a voltage divider just pulling pin 3 high or low seemed to work. So I hooked up the voltage divider and tested it with a 12V-14V source. All seemed well until I connected the voltage divider (R1) to 12V (while monitoring the voltage it was outputting) even though I saw only 3V on pin 3 the micro-controller went pop.
I'm not really sure why it popped, sorry if this is a stupid question but I'm not the best at this stuff. Any help is appreciated, thanks.

Edit: Genuine question, why do some of my questions get voted down?
Am I using this site wrong or formatting my questions wrong? I've been trying to learn electronics, but so far this site hasn't been of much help.
I don't really understand why some people vote down questions without telling the asker what they are doing wrong. If you could explain what they're doing wrong it can help them to not make the same mistake in the future (E.g. formatting wrong, not site applicable etc).


texts: What is the reference/name of this connector?

texts:
I would like to know the name/reference of this connector:

This is for 2.5mm² max wire
When you push the orange button, it unleash the wire

Thank you


texts:
Hello,I have this truth table.I did this table and I am creating a demultiplexer 1 in 2.Not multiplexer.
Second,I did
and that
I gave and those
Am I right?I want to confirm that I have done it all right


texts:
I want to use an ECS Crystal in my schematic and PCB layout in Altium, but I cannot find any downloadable libraries for ECS crystals despite ECS Crystal Oscillator. IntLib clearly being listed as an available library on Altium's website.

How do I locate and download these libraries?


texts:
I am trying to measure a machine's vibration using LIS3DH sensor.
I set the LIS3DH in low power mode and 5.376 kHz sampling frequency which outputs 8 bit output. I use SPI to get the data from the sensor. I changed this raw output into ’g' using the sensitivity value given in the datasheet.
My problem is: The sensor shows a fluctuation in its output of Z axis even when there is no vibration applied and the sensor is fitted on a horizontal surface. The range of this fluctuation is approximately from 0.6g to 1.2g. I have attached a image that shows such output. (X axis is time and Y axis is vibration in terms of g)

Can someone please help me to interpret why this is happening ? Is there a method to somehow remove this noise from the output ?


texts:
I'm trying to design simple multichannel ADC interface for recording live performances from audio mixing console. Many AD converter chips have differential input. Also direct output from mixing console is also differential.

Question is: Do I need to place differential ops amplifier in front of ADC chip or I can feed output from console directly to AD IC?


texts: Powering an Arduino with ATX power supply

texts:
I am working on a project that requires the use of a PC Power supply with my
Arduino Uno. I would like to use a Molex to power my Arduino and I have a few questions. My power supply is rated 18A on the 12V rail, and 28A on the 5V rail. My question is which rail would be best to use, and should I use Vin, 5V, or the DC power plug. Also, would the same advice work for an Arduino nano? All help is appreciated.


texts:
I am in the middle of a new design and I need to choose the right capacitor.

What is the impact of equivalent series resistance (ESR) in a capacitor?

When should I use a low ESR capacitor?


texts:
I was looking for a voltage controlled current source see here , and I stumbled upon this circuit with description here :

Now I am having difficulty figuring out how this works - I made a model of the circuit in SPICE and I am utterly confused.

When I measure the Gate voltage it shows up as 297 KV! - How on earth can it have that much gain. I do get the current through Load and sense resistor, as predicted. But when I use a general op amp model with reasonable supply voltages (5V and Gnd) to the opamp. I get output current in uA.

I am missing something here. What am I doing wrong?

I also found this with similar circuits.

I guess, what I am really asking is how things work when MOSFET is thrown in the op-amp feedback.

Edit:

I managed to get the expected output current with the new circuit -


texts:
I have an ADC sampling a downconverted RF signal at fs. I obtain N=2^15 samples of the RF input signal "fcarrier + fs/10".

The more I average, the more the entire noise floor shifts down (as expected, 10dB/dec) but also the phase noise skirt. I can average down to 100dB SNR (I didn't wait longer). For 1000 averages, the (zoomed) spectrum looks like this:

The phase noise skirt just moved down by 30dB as compared to the non-averaged version. This suggests I can average the phase noise out. But I would not expect it to be averaged out. According to http://www.bitsofbits.com/2015/07/07/signal-jitter-and-averaging/, the signal should be a cosine convolved with an exponential ("signal-leakage like") after infinite averages.

Can phase noise be reduced?
If yes, does can it be averaged out same as white noise? (This is what I observe above).
How does this fit into the link posted above?
Does it depend on the input signal? (sinusoid vs wideband)?


texts: analog to digital converter as voltmeter

texts:
I'm still student so excuse me if the question is not professional.
Basically ADC can convert any voltage within decided range to the digital form.

Isn't that what exactly the digital voltmeter does?

Why do we need the complicated circuit of digital voltmeter if only ADC is enough to do the job for us?


texts: What is the name of these colorful connectors?

texts:
What is the name of these colorful connector? Standard one or priority? One of the molex family? What is the exact name?

PS: The connector is used to attach speakers. There is a marking on each one that 'says' KL.

Anyone?


texts: Seeking advice on resistors in switching power supply

texts:
I am trying to repair the power supply in an LCD monitor. It is a fairly basic design around an OB2268AP in the 20-30 Watt range. The power supply had failed spectacularly because the main MOSFET short-circuited, vaporizing one pin on the regulator IC, burning 2 resistors to a crisp, damaging another plus some collateral damage.

Here's the part of the circuit after filtering and rectifying mains voltage, so there's some 300V DC between U+ and U-.

There are a few oddities on the PCB:

R706 is not a resistor but a choke inductor (makes sense)
ZD702 is not mounted
R708 is not a resistor but a zener diode. I can make out '24' at the end of its designation, so it's probably a 24 Volt zener

R710 and R712 were burned to a crisp so I can't make out the original values, and I need some advice on the values. The reference design for the OB2268 does not mention R710 but I suspect it's a low ohm resistor to have some 'protection' against the gate capacity of Q701. I guess something like 2.2Ω, 4.7Ω maybe? Any higher and the rise and fall times for the gate will suffer, I guess.

The one that has me stumped is R712. Pin 6 on the IC is the SENSE input of the current limiter. It has a threshold of 0.86 volt; together with R711 of 3.3Ω that makes a limit of 0.25 Ampère. If R708 is indeed a zener diode of 24 volt it would act as a secondary limit for the IC's own power circuit (D703, 'R'706, etc). So what's your guess for R712? Maybe the value is non-critical (the input resistance of pin 6 is 40 kΩ according to the datasheet), maybe it can't be too high else zener R708 won't work reliably.

Update: R711 is actually 0.33Ω

Update 2: I repaired it with the following components:

Q701: IRFB9N60A (600 V, 9.2 Amp mosfet)
R701: 2.2 ohm
R712: 1 kohm
I702: an optocoupler I had lying around :P

I hooked up an oscilloscoop to the gate of Q701 and the rising edge is a bit curved and there's a tiny bit of oscillation/overshoot but otherwise it seems okay; the descending edge is straight and sharp.

Note on the IRFB9N60A: in contrast to the original 7N80C this transistor not an isolated package.


texts: Regarding the standard data types, What is the size of an integer in ATmega controllers? And what determines the size, is it just the compiler? Or is it in the hardware design of the controller itself and therefore all ATmega compilers have to abide to that size? And if it is in the hardware, how come that in a PC you can have two different compilers giving of different results for sizeof( int) even thou they run on the same processor?


texts:
I tried solving this problem, however I feel like there's something missing, I am asked to bias a N-channel JFET with using this provided data:

Idss= 12 [mA]
VDD= 12 [V]
VP = -5 [V]
VDS=VDD/2

using a voltage divider circuit, however I can't seem to get an equation for the resistance values.

Here's what I've done so far:


texts:
If a P-channel MOSFET have absolute maximum values:

VDSS = -60 V
Vgs = +/-20 V

"refering to high switch side":

Does this means we cannot switch the MOSFET by the gate driver that ties the gate to ground if Vd > 20 V?

this means i cant use this gate driver on most of P-mos (most of them +/-20Vgs) if we apply VG(max) on Drain:

http://ww1.microchip.com/downloads/en/DeviceDoc/21424d.pdf


texts:
I have a conceptual question regarding the circuit below.

simulate this circuit – Schematic created using CircuitLab

With a Sine wave of any frequency f, with a peak of 1V, and -1V at the input node, what will be the output at point B?
If we remove the capacitor, and replace it with a short, how will the output at B will be effected?

What if we had a constant DC 1V at the input?


texts:
I have a question concerning reflections due to impedance mismatching. Now, assuming a lossless TL, the latter is modelled by sections of lumped L-C segments where L in a series (sub)element of the transmission line and the capacitors connect to GND. I understand that this models the two wires of the TL and mathematically leads to the characteristic impedance Sqrt(L/C) used to calculate reflections once source and load impedances are also known.. Now to my question.. I know how to compute the reflection coefficient when source and load impedances are given. But how do i calculate the reflection introduced by a series capacitance in the TL, right between the source and the TL? (Or between TL and the load). I assume i have to include the series C into source or load, respectively...but how to deal then (for example) when there are two TLs in series and the series C is right between those?

Thanks a lot for explanations ;)

Removed EDIT to a new question


texts: Well that's a quite simple question. I tried my chance with Google Images without success and tried some lists of images to be able to know what is this component. But I don't find it and there is nothing written on it.


texts: BJT - finding Ic with two opposite voltages connected to base

texts:
Here's a question from my homework:

Find \$  I_C  \$ and \$  V_{CE}  \$ for the circuits below, assuming \$  |V_{BE}| = 0.7V  \$ and \$  \beta = 100  \$.

I understand circuit (a), but for (b), I don't understand how to incorporate the \$  -15V  \$ branch into calculation.
Below is my attempt:

$$  R_{TH} = \frac {R_1 R_2} {R_1 + R_2} = 3.197 \times 10^5 \Omega  $$
$$  V_{TH} = \frac {V_1 R_2 + V_2 R_1} {R_1 + R_2} = 5.408 V  $$
$$  \therefore I_B = \frac{V_{TH} - V_{BE}} {R_{TH}} = 1.47 \times 10^{-5} A  $$
$$  I_C = \beta I_B = (100) (4.69 \times 10^{-5}) =  1.47 mA $$

Edit: Thank you all so much for the helppppppppp~


texts: 4-pin quartz resonators - shall the 2 ground pins be connected to ground plane of the pcb?

texts:
I am about to use a 8MHz quartz resonator that has 4 pins (http://datasheet.octopart.com/LF-XTAL026380.-IQD-Frequency-Products-datasheet-6993.pdf):
pin 1 and 3 are connected to resonator while pins 2 and 4 are grounded (I checked that they are shorted to a metal casing).

Shall I connect pins 2 and 4 to ground plane of my pcb or leave them not connected?


texts:
I have this 30W desoldering tool from Velleman which I've used a few times without any issues... until I decided I wanted a finer nozzle.

I turned it on after replacing the tip , and the base just melted:

Note that I did not unscrew the base: the screws just popped out when the plastic melted.

Now the base becomes hotter than the tip, making it effectively useless since the tip does not heat up enough to melt solder.

The spare nozzle look like this: nothing special, just unscrew it and screw the new one in.

I know it' just a cheap tool, but did I do something wrong? I did have to use some force to unscrew the tip when I replaced it (fine, I used pliers) but could that have caused this defect?

Thanks!


texts: 555 timer only works when I disconnect pin 4 from V+ and touch the jumper

texts:
I set up a pulse circuit on a breadboard with a 555 timer. Input voltage is 5 V. My values are roughly:

C = 100nf
R1 = 1K
R2 = 1M

I'm using this schematic:

(Source: https://www.allaboutcircuits.com/tools/555-timer-astable-circuit/)

This should produce 3 - 4 Hz at the output. When I power up the timer I get a frequency generated at about 150 Hz. Strangely when I disconnect the jumper from V+ (leaving it connected to pin 4), and touch the exposed end of the wire, the circuit works perfectly - outputting 3 - 4 Hz.

This is very weird to me. I tried some different resistor values and capacitors and it's the same result every time.

Any ideas?


texts: Measure peak voltage / amp, when signal is very short (relay on/off)?

texts:
I was measuring a 'steer' signal for switching on a relay. The oscilloscope, gave me back it peaks at around 2.64V. The width of the signal is 132ms.

I then hooked up my multimeter, to measure how much amp was drawn. However the reading varies (between 4 - 14 mA). Which made me wonder.

My question: is there a minimum amount of time a multimeter needs to 'register' a correct load? In other words, is 132ms long enough to get a decent reading?

If not, what would be a correct way of measuring?

If it matters,  it might be depending on the 'quality' of the multimeter? I used a UNI-T (UT61).


texts: Converting a long low pulse to a short low pulse to wake up an ESP-12F

texts:
I'm trying to wake up an ESP-12F from deep sleep mode by pulling the RST pin low for a brief moment (~10ms or less).  I thought I needed a monostable (one shot) circuit so I bought an LMC555 timer to take a low pulse and output that as a fixed 10ms low pulse to the RST pin.

Reading and understanding more about the LMC555 timer I realized it may not work for my situation.  My wake up signal source could last anywhere from 100ms to several hours (moisture sensor), but I need to generate just a single 10ms pulse and can't have it repeating.  I need the ESP-12F to wake up just once, do some work and then go back to sleep.  I don't think the LMC555 will work for me because the trigger pulse needs to last for a shorter period of time than the output pulse.  So, if I'm looking to generate a 10ms high pulse out the output pin of the LMC555 my trigger pulse needs to be less than 10ms.  Unless I'm reading this section of text from the TI datasheet incorrectly "During the timing cycle when the output is high, the further application of a trigger pulse will not effect the circuit so long as the trigger input is returned high at least 10 µs before the end of the timing interval.".  In my case the trigger input will NOT be returned to high before the end of the timing interval.

Hopefully, I've explained this properly.  To simplify it I'm trying to figure out how to take a low (ground) pulse that could last anywhere from 100ms to several hours and have it generate a single 10ms low pulse.  My power source is an 18650 battery which could be anywhere from around 4V to 3.3V.  If I can still use the LMC555, great, otherwise I'm back to square one.

How do I generate a regular 10ms pulse with a 555 timer from a Vbat voltage that varies?


texts:
In the manual of my STM32, one of the GPIO Alternate Functions (namely AF15, see page 138) is called EVENTOUT. At no point is the event defined, or a use case given.

What is the EVENTOUT alternate function of my STM32?


texts:
I recently learnt about the existence of PTC fuses, and I'd like to use one for an USB power supply I'm building. I guess there are PTC fuses on the PC side, but you never know.

I went happily to buy some at my local electronic supply store, but unfortunately they said they don't have resettable fuses (weird, they've got almost anything.) Since I'm spanish I didn't ask for PTC fuses, but asked for resettable fuses and explained how they worked, in case they're called something else here at Spain. They didn't have the fuses or knew where I could find them.

I've read PTC fuses are essentially thermistors, is it possible that they know them as thermistor or some other name, instead of resettable fuse?


texts: Impedance matching between CSR8675 and a MM20 microphone

texts:
I'm building my own (rugged) headphone. I am planning to use a MM20-33639-000 microphone with CSR8675 DSP. My question here relates to impedance matching.

Based on what I have read, most modern audio equipment use voltage matching as opposed to impedance matching (if there are multiple devices powered) to preserve the voltage across each input of the destination block. Anyway, let me start with some facts.

The output impedance of the MM20 microphone is 5100 ohm (max = 6350 ohm).

The CSR8675 datasheet states the following:

"When the input pre-amplifier is enabled, the input impedance at MIC_LN, MIC_LP, MIC_RN and MIC_RP varies between 6k Ohm (pre-amplifier gain >0dB) and 12k Ohm (pre-amplifier gain = 0dB)."

I am planning to use 2 microphones. The CSR8675 accepts 2 input lines individually. Therefore each microphone gets its own pre-amplifier (no sharing needed.)

As can be seen above, the output impedance of the mic and the input impedance of the preamp on the CSR8675 are pretty similar (6350 Ohm and 6000~12000 ohm). Since I'm not sharing the mic output across multiple pre-amps, I think I can stick to the concept of impedance matching (not voltage matching) without having to worry about if the signal voltage will drop across the pre-amp input and hence causes noise issues (SNR degradation). From what I have read, if I do voltage matching, the preamp will need to have an input impedance that is 10 times larger than the mic's output impedance.

Is my selection of devices based on impedance matching correct and use these two components, or do I have to use a preamp that has a higher input impedance?


texts: How can I measure the reverse leakage value of a TVS diode?

texts: Compared to the component's datasheet without protection circuit, for quality control purposes. Can I use a multimeter for that?


texts: Controlling motor with potential on 2 points

texts:
I have 2 nodes where minimum voltage is 2.7v and maximum voltage is 5v. I would like to turn ON a motor when both nodes have 5v and turn off when both nodes have 2.7v.

Node1 - 5v & Node2 - 5v      Motor ON
Node1 - 5v & Node2 - 2.7v    Motor ON
Node1 - 2.7v & point2 - 2.7v  Motor OFF

How can i achieve this??


texts: Matching LCD controllers to LCD compatible panels

texts:
Over the years, I've accumulated numerous LCD panels and controller boards salvaged from TVs, Monitors, Cell Phones, digital picture frames, GPS devices and tablets. I would like to reuse the panels with the discrete controllers in my electronics projects.

I may have some proprietary panel and controller configurations, but I presume the vast majority are just stock. Is there a "rule of thumb" or a specification list for determining the compatibility of a controller with an LCD panel?


texts: Inverting SMPS - tantalum and part selection | Monolithic controller getting hot

texts:
I'm designing a circuit to provide a negative voltage rail in a battery for an ADC. I've decided to use a particular monolithic BCD Chip that can work as a step up/down/inverting controller and has an integrated switch.
I've designed the circuit inline with the data sheet inverting reference with the exception of using tantalums, a different shottky (30V 1A) and have a higher input voltage. At this point it doesn't appear that the circuit is switching (at all) from what I can tell, there is no oscillation on the timing cap pin or output, and Vout is measuring around +.3V. The chip is commanding 3W of energy which it appears to be dissipating itself.
Have I missed something here. I've substituted all components, so this is likely a design or layout issue I think.


texts: Why do we assume VGS0 for a mosfet in cuttoff and Vce>0 for a BJT in cutoff?

texts:
The devices below are both n polarity devices, the BJT is a NPN and the MOSFET is a NMOS.

For the BJT in cut-off, why do we have to assume \$V_{ce}>0\$?
For the MOSFET in cut-off, why do we have to assume \$V_{GS}<V_{th}\$ and \$V_{DS} > 0\$?

Where VGS is the gate-source voltage and Vth is the threshold voltage.

simulate this circuit – Schematic created using CircuitLab


texts: Removing the load of an AC signal to a DC signal

texts:
simulate this circuit – Schematic created using CircuitLab

I built this circuit to visualize music with LED's using a full-bridge rectifier I got from a vacuum(meant for 120VAC to 120VDC, with a 270uF 250V capacitor) and the first part of a flash ADC converter. When the reference voltage for the ADC converter comes from the audio amplifier, the audio amplifier heats up from what seems like an overcurrent draw. Is there any type of circuit that removes the load from the audio amplifier and puts it onto a DC load? Are there any obvious ways I could decrease the current load on the audio amplifier?


texts: Why are the transistors in logic circuits used in saturation region for ON state?

texts:
This is a beginner question. I know how the logic gates with BJTs work basically to provide ON and OFF switching action. OFF state occurs when the transistor is blocked in cut-off region, and ON state occurs when the transistor conducts between the collector and the emitter.

So ON state occurs in both active region and the saturation region.
I wonder in logic circuits why better to saturate to obtain ON state instead of conducting in active region? Active region seems to be avoided. Is that for stability or heating? Why?


texts: Hardwire rgb-led-controller instead of Infrared

texts:
I think most of you know these cheap rgb-strip-controllers with ir-remote. I try to control it via hardwired gpio from raspberry3, simply replacing the ir-receiver.

from

|ir remote|.......>...|IR-LED GP3 µc|

to

|rpi GPIO out|----->----|in GP3 µc|

I found these informations about the box:

12 V In
SMD5050 RGB Strip 4Wire
SOT23 NFET, max 3A
IR Sensor CHQB, 3Wire
8bit 8pin µc with 5V TTL Logic
at least 3x PWM
maybe PIC12F617

Pinout on this µc:

        GND - XX - 5V
        GP5 - XX - GP0 - B Out
        GP4 - XX - GP1 - R Out
IR IN - GP3 - XX - GP2 - G Out

http://ww1.microchip.com/downloads/en/DeviceDoc/41388A.pdf

Is it possible?!

1. controlling via wired GP3 (IR)-Port?

Seems, the carrier-demodulation (35KHz) is inside the ir-receiver.
How do i have to encode/recode the ir-data to be understood by the µc?
Is it a simple pseudo-serial-in-port with a distinctive baudrate?
clearly saying "i want to bypass the ir-path"
benefit short commands and no hustle on raspberry
disadvantage only able to use µc-saved commands

2. connecting directly to the NFET (Q1-Q3 on picture)?

Do i have to level-shift 3,3V to 5V?
benefit all is possible
disadvantage need to code it all on raspberry


texts: What is maximum supported RAM for Snapdragon 410?

texts:
Qualcomm Snapdragon 410 datasheet says:

  Memory
  + LPDDR2/LPDDR3@533MHz
  + eMMC 4.5
  + SD 3.0 (UHS-I)

It does not talk about maximum amount of RAM supported. What is the maximum amoount of RAM this processor supports?


texts: How is it that two electric currents can travel in opposite directions on the same wire, at the same time, without interfering with each other?

texts:
An Introduction to Information Theory: Symbols, Signals and Noise, by John R. Pierce, says the following:

While linearity is a truly astonishing property of nature, it is by no means a rare one. All circuits made up of the resistors, capacitors, and inductors discussed in Chapter I in connection with network theory are linear, and so are telegraph lines and cables. Indeed, usually electrical circuits are linear, except when they include vacuum tubes, or transistors, or diodes, and sometimes even such circuits are substantially linear.
Because telegraph wires are linear, which is just to say because telegraph wires are such that electrical signals on them behave independently without interacting with one another, two telegraph signals can travel in opposite directions on the same wire at the same time without interfering with one another. However, while linearity is a fairly common phenomenon in electrical circuits, it is by no means a universal natural phenomenon. Two trains can’t travel in opposite directions on the same track without interference. Presumably they could, though, if all the physical phenomena comprised in trains were linear. The reader might speculate on the unhappy lot of a truly linear race of beings.

Thinking about this from a physical perspective, I was wondering how it is that telegraph wires are linear, in the sense that two telegraph signals (in other words, two electric currents) can travel in opposite directions on the same wire, at the same time, without interfering with each other?
I was naively thinking about the wire as a single-lane, two-way road. In this analogy, the cars would be able to travel in either direction, but not at the same time. As I understand it, in solids, movement of electrons produces an electric current, so the electrons would be the cars. Given the author's explanation of linearity, what is going on here with the electrons that allows this concurrent, two-way flow of current?
I didn't find anything on the Wikipedia page for linear circuits that clarifies this physical property of linearity.
I would greatly appreciate it if people could please take the time to clarify this.
P.S. I do not have a background in electrical engineering, so a basically-worded explanation is appreciated.


texts:
I will be using the following FPGA
https://store.digilentinc.com/nexys-video-artix-7-fpga-trainer-board-for-multimedia-applications/
I have a module who has 16 std_logic_vector (13 downto 0) outputs
The values of these outputs are changing every 50 Mhz on every rising edge of my FPGA_clock.
I want to store these datas on an SD CARD and be able to read back the data out of the SD Card.
But i don't know if it is possible to read and write on the SD CARD using the signals:
VDD
DAT2
DAT1
CMD
CLK
DAT3
DAT0
CARD_DETECT
Is there any document that explains how to control these signals to write and read on a SD CARD via an FPGA?
Thank you for your help


texts: FPGA SDC timing constraints, understanding output delay

texts:
I'm having a little bit of trouble understanding the timing convention of an SDC command:

set_output_delay 1.0 -clock_fall -clock CLK2 –min {OUT1}
set_output_delay 1.4 -clock_fall -clock CLK2 –max {OUT1}

Does this mean that after the launch clock (CLK2 falling edge), the output signal (OUT1) is allowed to transition between these min/max windows (signal edge occurs somewhere beteen 1.0 ns and 1.4 ns after the falling edge of CLK2)?

So is it basically the inverse of describing where a signal will needs to be valid: where it is allowed to transition/describe where the signal can be invalid?

Is my understanding correct?


texts:
This question is regard to enhanced n-type MOSFETs.  From what I understand, an inversion layer is formed underneath the insulating layer below the gate of the MOSFET when a voltage is applied to the gate.  When this voltage exceeds \$V_\mathrm{T}\$, the threshold voltage; this inversion layer allows electrons to flow from the source to the drain.  If a voltage \$V_\mathrm{DS}\$ is now applied, the inversion region will begin to taper and eventually, it will taper so much that it will pinch-off, once it has pinched-off (it can no longer shrink in height), it will then begin to shrink in length (width) becoming closer and closer to the source.

My questions are:

Is what I've said so far correct?
Why does this pinch-off occur?  I don't understand what my book says.  It says something about the electric field at the drain being also proportional to the gate.
It is my understanding that when the MOSFET is saturated, a depletion layer forms between the pinched-off bit and the drain.  How does current flow through this depleted portion to the drain?  I thought the depletion layer does not conduct...  Like in a diode...


texts: Datasheet electrical characteristics parameters confusion

texts: I'm reading the datasheet of DAC8512. What I can't understand is about some pulse widths, the indicated minimum value is larger than the typical value.  Is this the datasheet mistake or I misunderstand something?


texts: Comparator output not fully switching on MOSFET

texts:
First Question for me.  I have benefited from other answers here but have not fully resolved my problem.  Here's my problem...

The LM311 Comparator output does not drive the N channel MOSFET fully on.

The LM311 has a 110mv ref voltage on the inverting input.
The non-inverting input is driven by an opto-isolator output.
The Opto-isolator is driven by 1 of 4, AC 60Hz voltages.  <1VAC, 9VAC, 55VAC and 115VAC.

The goal of the design is to have the FET fully turn on the 12VDC fan when there is appreciable AC voltage.  So fan fully On for the 9, 55, and 115VAC voltages.  It seems it should work because I measure voltages on the non inverting input of 1.6, 2.2 and 3VDC respectively for the 3 appreciable AC voltages.  And my ref voltage on the inverting input is 110mv.

So it "almost" works because the fan is off at the <1VAC, but not fully "On" for the other AC voltages.  I believe this is because Vgs is 167mv, 6.1V, 7.7V and 9.9 Volts for the 4 AC voltages listed above.  And the fan is only getting 7, 8 and 10VDC instead of a desired 12VDC.
Would really like to be able to fully turn this FET all the way on.  So Close!

Any input or guidance is appreciated.

Ps-Things I think I've done right?
Flyback diode across the fan.
Putting N channel FET to switch to ground on low side of fan.
LM311 has Open collector output using correctly?

PSS-I realize that the pinouts for the LM311 are not right in my schematic.  I have them right in my protoboard circuit.  Its a single device.  Pin 2 is noninveritng and pin 3 in Inverting

Thanks Again.

The suggested duplicate question and answer doesn't help for the following reasons:
Both diagram and schematic are"No file found" making it pretty difficult to follow the answers.
I am not using any positive feedback in my circuit as I don't think I need one.
I have a simple pull up resistor to my 12V supply, not a voltage divider to the power supply as is mentioned in the answer.
Thanks.

Just for the record I wanted to post a more accurate schematic and thanks for the response on using a Cap to hold up the opto isolator output. I actually have a full wave input to the phototransistor but I'm sure the cap will help anyway. To answer the last question, the Pin 7 comparator output has a pullup resistor to 12v. The issue is still that Vgs is only 10v when the comparator has 3v on pin 2 and 110mv on pin 3. I would have expected the LM311 output to go much closer to 12v (Vcc) with those inputs. The intent is for the FET to go completely on for pin 2 voltage > pin 3.


texts: How to simulate magnetic field of a toroidal solenoid?

texts:
I am trying to simulate the magnetic flux inside and outside of a classic toroidal solenoid. The simulation must be able to simulate a toroidal solenoid with several densely wound layers of copper wire.
The issue is that I can create a toroidal coil from a parametric curve, but am limited to one layer of windings and am computationally limited in my number of turns (meshing alone takes hours). COMSOL allows you to create coils by defining a direction of current flow and specifying a number of turns. This would solve the meshing problem, but I have not been able to implement this for a toroidal coil. I am unsure of how to proceed.
Which simulation tool should I investigate for this task? In short, I have looked into ANSYS and COMSOL, but have trouble creating a simulation of the magnetic field through a toroidal solenoid with multiple layers of windings.
I would be extremely grateful for any pointers, as I have been puzzling over this for two weeks.


texts: Looking for a Micro-USB socket with the same external geometry as Mini-USB

texts:
I'm looking for a Micro-USB socket which has the same external size as a Mini-USB socket. This is to allow us to update some old products to use Micro-USB without us having to modify all the tools which are used to create the plastic housings. I thought that there may be something on the market specifically designed for this purpose. We can update the PCBs to use new solder pad positions without any problem.

Any help much appreciated. Thanks


texts: Timer on PIC18 not getting close to desired interrupt period time

texts:
I tried to setup Timer0 on a Microchip PIC18F46K22 so that it will trigger an interrupt and toggle an LED. However, it takes at least 42 µs for the LED to toggle.

At an increment rate of Fosc/4 (= 8 MHz/4 = 2 MHz), a TMR0 preload of 0xFF and a two cycle loss when writing to TMR0 I expect to get an interrupt every 1.5 µs, at least on paper. Even if I factor into some instruction cycles for my LED operations, I can't figure out why it takes 42 µs. What's wrong here?

Here's my code:

volatile unsigned char ledStatus;

void greenLEDon(void)
{
    LATCbits.LATC5 = 0;
}

void greenLEDoff(void)
{
    LATCbits.LATC5 = 1;
}

void interrupt isr(void)
{
    if(TMR0IE && TMR0IF)
    {
        if(ledStatus == 0)
        {
            ledStatus = 1;
            greenLEDon();
        }
        else
        {
            ledStatus = 0;
            greenLEDoff();
        }

        TMR0IF = 0;            // Clear interrupt flag
        TMR0 = 0xFF;           // preset for timer register
    }
}

void setup(void)
{
    OSCCON = 0b01100010;    // 8 MHz, internal

    // General outputs
    TRISCbits.TRISC5 = 0;   // RC5 (green LED)

    INTCON = 0b01000000;    // PEIE on (Peripheral Interrupt Enable)
    INTCONbits.GIE = 1;     // General Interrupt Enable

    // Timer0 Registers
    T0CONbits.T0CS = 0;   // TMR0 Clock Source Select bit: 0 = Internal Clock (CLKO)
    T0CONbits.T0SE = 0;   // TMR0 Source Edge Select bit: 0 = low/high
    T0CONbits.PSA  = 1;   // Prescaler Assignment bit: 0 = No Prescaler is assigned to the Timer0
    TMR0 = 0xFF;           // preset for timer register
    T0CONbits.TMR0ON = 1;
    T0CONbits.T08BIT = 1;
    INTCONbits.TMR0IE = 1;
}

void main(void)
{
    setup();

    while (1)
    {
    }
}


texts: custom circle copper fill in ares proteus

texts:
My work needs to design a custom circle like the picture below.

I need to copper fill the portion in between the two circles. I've tried zone select mode, but it doesn't work efficiently as I need. Is there any option to do it?


texts:
I'm trying to make my own PID temperature controller using Arduino.
Arduino PID library outputs a PWM signal.
I need to control 230VAC using this PWM like a triac  phase angle controlling.
If I use a triac phase angle method, I have to dedicate lot of processing power for zero-crossing detection for interrupt.

Is their any alternating way to do this?


texts: Minimum limit for current and maximum limit for voltage while calculating power

texts:
I have a brushless Motor then i am using in conjunction with a ESC, powered by a Lithium Polymer Battery(3S 1300mah). I just got a new Lithium Polymer battery (6S 15000mah) from a friend and am planning on using it to power my motor.

From the motor details shown by the manufacturer here:- http://www.emaxmodel.com/views.asp?hw_id=15   , it shows the motor being rated at 3S 17A MAX. If i were to calculate it's wattage, it would be (4.2 * 3) * 17 = 219.3W, assuming a voltage of 4.2V per LiPo Cell. However, as 17A is the max rated current, and that the max continuous current is not given, i would be using 15A as an estimate, which would give me a wattage of 189 Watts.

While the motor is shown to be using 3S LiPo batteries, would i be able to power it with a 6S LiPo Battery with a lower current draw?( I'm assuming that the motor will draw less current since more voltage is supplied to it).

Am I right in thinking that i should be able to power the motor with a variety of voltages, as long as the power(voltage * current) does not exceed the max rated wattage of the motor?

If so, given an extreme example, would i be able to power the motor at 100V @ 1.89A(not that it would be feasible or would i ever do it), or is there a max limit to the voltage and/or a min limit to what the current supplied must be for the motor to work?

All thoughts, opinions and answers would be greatly appreciated.


texts: Turning off IC's when not used in battery powered circuit

texts:
I'm building a small battery powered device which contains an ATTiny85 micro controller, a dual common anode 7 segment display and 2x595 shift registers to drive the 7 segment display.

The device will spend most of its time sleeping. While in sleep mode, the 7 segment display will be off. The 595s have a worst case quiescent current of 160uA so with both of them on its a full 320uA of wasted current.

What would be the most efficient method of turning off the 595s when they are not used?


texts:
How we can find the equation of following simple diagram ?

My TA solved it as :  C.Not(B).A + B.Not(A)


texts: Is the LT8500 a current source or sink on its PWM outputs?

texts:
I am using the LT8500 as an LED driver and I need to know if the leds are current sink or source.

Also if I need to have resistors in serial with the PWM outputs since the output voltage is 4V.

I've looked through the whole datasheet and I'm not finding anything at all so any help would be great.


texts: How can a micro controller turn off itself by closing the VCC line when battery is low?

texts:
My board has a Li-ion battery with the capacity of 4000mAh and maximum voltage of 4.25V and minimum voltage of 3.25V . This means that the battery voltage shouldn't get lower than 3.25V.

When the adapter connector (the input 12V 3A voltage) is removed , all of the components of the circuit turn off except a micro controller that uses the battery voltage until the battery voltage reaches 3.45V and one LED to show that battery is discharging.

The micro should be apprised of the lowness of the battery when the battery voltage is 3.45V (0.2 volts higher than the minimum voltage) and copy important data to EEPROM and then turn itself off to avoid battery discharge much and become unusable.

The micro controller will be still off until the adapter connector connects to the board again and then it will recover the important data from EEPROM to SRAM and continue its work and also control charging the battery with PWM until it get fully-charged.

How can the micro controller (ATMega32A) turn off itself ?


texts: Why do some power adapters output an AC voltage?

texts: Out of most of the electronics I use, I have two, both of them speakers, that use a power adapter that simply steps down the voltage without rectifying it. Why did the designers choose to put the rectification circuitry in the speaker instead of the power adapter?


texts:
I am having a problem creating a cable to connect with two devices. The first devisce is an Intellivue MP70 that I want to connect to the RS232 port using an RJ45 end. On the other side there should also be a RJ45 connection that should be connected to a Lantronix EDS-MD Server, and i can't figure out the pin assignment.

I got the following image:

And the following table:

However, as you can see this is a connection from RJ45 to DB9.
How do I translate this so i get RJ45 on both ends of the cable?

I can also mention that I have access to a RJ45 to Screw terminal adaptor on one side.


texts: CMOS inverter explanation (low level output)

texts: Having a simple CMOS inverter considering Vdd 5v and Vss 0v, when the input (A) is high (5V), why the output is pulled low (Q) (0V). In my understanding when a N-MOSFET has it's drain floating (in air), source to ground and Vgs > Vth will not pull the drain to ground (if there is no pull-up on output). Is there something I am missing?


texts: Measuring the HSE frequency of an STM32F2

texts:
I am programming an STM32F2 (manual here). I am having clock problems and would like to check every clock using an oscilloscope. The first clock I want to check is HSE, which stands for: High Speed External (Clock).

How can I use an oscilloscope to measure the HSE frequency of my chip?


texts:
I am trying to design a half bridge isolated DC DC converter but I am encountering some issues.

Is there an effective way to come up with a minimum value of capacitors C1 and C2. In all the papers that I read, they just seem to come up with a value as big as possible. The tricky thing is that I will not use any electrolytic capacitors, only film and ceramic ones in my design. This means that I cannot really use a very high value, but I am however using a very high switching frequency (100-500kHz probably). So I hope that this might reduce the need for a very large capacitor.
It seems from Link 1 that there might be a problem regarding converter stability when a current mode controller is used. I am wondering if this converter could cause a problem when voltage mode control is used and the converters are placed in parallel... As I have always read that you need current mode control in order to put SMPS in parallel. Does anybody have any experience in this area regarding the stability of half bridge converters and paralleling them?

I have added a quick drawing for completeness.


texts:
As the picture describes, the Vout is the division's result, but we have an error. Because my experience with MultiSim is not at a high level, why does this happen? Is this my fault ?

]1


texts:
I thought that hooking the same wire into two pins(2 and 3, on an Uno) would work, but it doesn't appear to be.

The sketch looks like such.

byte b;

NewSoftSerial nss(2,3);

void setup()
{
  nss.begin(9600);
  Serial.begin(9600);
}

void loop() {
  // if theres data from the bluetooth module
  if (nss.available()>0) {//this is never true
    //echo it to the serial monitor
    Serial.print("nss echo:");
    Serial.println((char)nss.read(),BYTE);
  }
  if (Serial.available()>0) {
    b=Serial.read();
    //echo it back to the serial monitor
    Serial.print("serial echo:");

    Serial.println(b,BYTE);
    //send it to the bluetooth module
    nss.print(b,BYTE);
  }
}

I expected to see pairs of outputs for every input.

  serial echo:g
  nss echo:g

What am I doing wrong?


texts: Is this a good circuit for detecting current path to ground?

texts: I basically need to detect if the switch is closed (the application is a water level sensor where current flows to the grounded tank through the water). Is this a good design, or how can it be improved? The op-amp would be normally positive but go negative when the switch is closed. The resistance and switch at the bottom represent the water. The resistances would be chosen to work well with the resistance of the water(so the values are just illustrative).


texts: MOSFET source measures 12V, still nothing will turn on

texts:
Please, bear with me, I'm a real rookie at electrical engineering. So please be easy on me. ;-)

I've got the following circuit. I have a 5 seconds HIGH / LOW interval on D5 and am seeing the voltage drop to near 0 and rise to 12V when measuring with my multimeter on the terminals of the speaker. Still, my Piezo speaker won't make a sound. When connecting it straight to the 12V source, it works as perfectly. What am I missing? Current at the source of the MOSFET I guess? But, why? Did I connect it wrong?

P.s. also tried connecting a LED with a 470 ohm resistor after the MOSFET, but that does not turn on either. And this also simply works directly on the 12V power source.

Transistor used: IRF520N (datasheet)
Voltage Regulator used: L7805CV (datasheet)
Piezo speaker used: BU2 M28 (datasheet)


texts: What is EMC recommended circuit and is it necessary?

texts:
I'm building a power supply with five isolation dc-dc converters, here is their data sheet https://www.cui.com/product/resource/pdqe15-d.pdf
The data sheet mentions a EMC recommended circuit, below a simpler version of the circuit, see below.
Is the EMC circuit necessary? I'm not going to be subjecting the power supply to any magnetic fields.


texts: AC Measurements: Level Shifter vs Negative Voltage Supply

texts:
I’m trying to design a circuit capable of measuring AC signals with a high level of accuracy. The two most popular options I’ve seen so far are:

a) Supplying the ADC with a negative ground supply (2.5Vref, Vp=2.5V, Vn=-2.5V)

b) Using an op-amp to first divide, then shift the input voltage to be in the range of 0-2.5V.

If my main goal here is acccuracy while minimizing power consumption, which of these two options would be my best bet?

To be more specific:

AC signal between -2.5V and 2.5V (divided down from 0-1000Vp via a resistor network). Accuracy anywhere between millivolts and microvolts, frequency range from 0-100kHz, and I’m using the AD7768-4 combined with the LTC6269IMS8E-10#PBF op-amp.

Thanks for your help!


texts: How can I detect when an LED changes color from red to green and quickly send a message to a PC to capture an image from a camera?

texts:
I am working with a 3rd party IR curtain system, and the only way to tell in real-time that something has pierced the curtain is an LED at the top of the sensor pole that changes from green to red when there is an object in the way.

My goal is to grab an image from a 60fps camera at the moment the curtain is pierced by an object (in this case a dog running full speed through the IR curtain).

It has been suggested that a phototransistor (with a filter that only allows red light to pass) can be used to quickly sense when the LED changes color to red.

Beyond that, I am guessing that an Arduino or Netduino could be used to sense the phototransistor change and then send a message to a PC/Mac to let it know to capture the image (or most likely, to grab an image from a ring buffer that is 50-100ms in the past, so it gets close to the exact moment the object passed the IR curtain).

So, my questions to this StackExchange is:

Is this a good approach in general?
Any suggestions on what phototransistor to use?
Any suggestions on where to find a filter that will only allow red or green light to pass to the phototransistor?
What is the best way to get a message from a Arduino/Netduino to a host PC/Mac in a timely fashion (I'm guessing RS232 is out for speed reasons - and it seems to USB may be problematic)

EDIT:

Turns out the gel filters are not needed.  Since the response curve of the photoresistor is at its peak at around the green wavelength and tapers off near the red wavelength, I can reliably tell the difference between off, green, and red by just the resistance indicated by the photoresistor.


texts: Color coding guidelines for selecting power indication LEDs

texts: Is there any industry-defined guidelines to select the color of LEDs which is used for power indication in systems? A colleague told me that red color LED is usually used for 12V, green for 5V and orange/amber for 3.3V. I couldn't find any relevant results in the web while googling for that also.


texts:
I'm doing this project, where i control the speed of a motor with a 0-3.3 V PWM signal from a microcontroller. In the test setup i use a function generator (Digilent Analog Discovery). I would like the PWM to run at 50 kHz, but for better measurements, I have lowered the frequency to 15 kHz, 50 % duty cycle.
My problem is, that there seems to be some sort of capacitance in my circuit, lowering the FET's rise time, when i test it.

The schematic:

"Opdrifts_PSoC-Blæser_signal" is the microcontroller. It is here i supply the - PWM in my test setup.
"R6" is where the motor will be. In the test i use a 10 kOhm resistor.
"Scope" is where i measure relative to ground.

The measurement:

Output signal

Rise time is measured to about 13 us.

Hope somebody here can help me out.


texts: MAX3232 CAE outputs -6V / +6V instead of -12V / +12V

texts:
I bought a GN801 GPS module from Stoton
( http://www.stotoncn.com/gnssmodule/showproduct.php?lang=en&id=42 )

Power supply range is +5V.
There is an onboard MAX3232CAE that is supposed to output RS232 signal.

I need to connect this module to a third party system that only accept RS232 with -12V / +12V signals levels.

When viewing MAX3232CAE TX pin trace with an oscilloscope, i can see it outputs -6V / +6V signal.

Wasn't MAX3232 supposed to output -12/ +12V signal, did i miss something here ?
This GPS module also exists in version with TTL output rather than RS232, if i go with TTL outputs (0-5V) how could i get a real -12V / +12V RS232 output since MAX3232 looks not to do so ?

Thank you very much for your lights on this and best regards,


texts: input resistance of differential amplifier

texts:
i have a question about the differential amplifier
i know that the input resistance for the common mode is

Rin = rpi + 2 Beta Ree / 2
but my question is what is the input resistance for the differential signal ?
this is the small signal equivalent circuit


texts: Same diodes (BAT54) from two manufacturers with different LTSpice characteristics?

texts:
Leaving the package and the resulting thermal characteristics aside, do diodes with the same name from different manufacturers have the same characteristics?

I would think they should, but when comparing a BAT54 from Diodes and NXP in LTSpice, I get different results.

NXP BAT54, SPICE model under "Documentation"

Diodes BAT54, SPICE model listed under "BAT54(Z)"

I simply put the diode in a DC sweep circuit from 0-2V and measured the forwardvoltage and -current.

What I got was:

Diodes BAT54: 200mV@1mA ; 254mV@5mA ; 287mV@10mA

NXP BAT54: 225mV@1mA ; 278mV@5mA ; 309mV@10mA

Is one model more accurate than the other? Or did I mess something up?
The Diodes file is a .model, the NXP is a .subckt with an additional resistor.

I copied the spice files (NXP_BAT54.prm and Diodes_BAT54.txt) into the folder with the LTspice circuit, added a standard Schottky, renamed it to BAT54, set the Prefix to D / X and added the files with a ".lib NXP_BAT54.prm" command.

When I put both curves on top of each other, you see the difference:


texts: What does Ch-Ch isolation stand for regarding this context?

texts:
This scope specs mention the following inputs:

I don't understand what meant by channel to channel isolation here. I made a continuity test and the input grounds of two channels are connected. I thought Ch-Ch isolation meant the input channels' grounds are isolated but obviously that's not the case. But then what could be meant by Ch-Ch isolation here?


texts: Is a flyback diode necessary for a small sg90 servo motor?

texts:
I am powering a small sg90 servo motor (see datasheet) directly using a 12V battery and a simple circuit to step down the voltage to the appropriate one for the servo. I noticed the servo has some coil windings and I suppose I could model it as an RLC circuit.

My question is, how can I know if a flyback protection diode is needed in cases like this? The manufacturer does not seem to care about the inductance since there is no mention of it in the datasheet...

I've already make some brief tests such as a few 90 degree turns and everything went well so far so I guess it is not vital to put such a diode (at least with short usage periods) however I would like to get some enlightment on this topic.


texts:
I am creating a circuit in Logisim which allows two players to play a game of Tic Tac Toe. The game begins when the "Begin Game" button is pressed. When it is pressed, a random player is selected to make the first move. I have used D Flip-Flops throughout my circuit.

Here is my D Flip-Flop circuit on the top left, as well as what the game looks like on the exterior after the "Begin Game" button has been pressed:

Here it is on the interior (I have removed the rest of the circuit to focus on the area my question is relating to), and below is the circuit for the Random Player Generator (Including a D Flip-Flop and a Random Number Generator which, in this case, outputs either 1 or 2):

As you can see, my Random Player Generator is functioning as it should. However, my problem is now with switching players. Once a player takes their turn, they press their "End of Turn" button and then the "Player X's Turn" lights should swap. I have been struggling to figure this out for quite a long time and have made no progress. I would appreciate any help on how I would achieve this or any suggestions as to how I can implement this changing player function as well as the initial Random Player Generator into my circuit in a better way.


texts:
I have a project that runs on 5V and should draw a maximum of around 500 mA. There is an existing CAT5 cable running conveniently to this project. I'm considering powering the project by using two of the wires in the CAT5 (which I assume is 24 AWG) by connecting it to a 5V - 2A power supply.

Is this safe? Is the amount of power my project draws (500mA) the determining factor for safety or the rating of the power supply (2A)?

Testing shows there is no problem with voltage drop-off.


texts: What motor driver should I use based on amps?

texts:
I am building a robot that sports 2 motors ripped from an old RC car. After many attempts to find the data sheets, nothing of use turned up. So, I ran some test and found this out about the motors.

Operating Amps(No load): 130 mA
Max Eff: 500 mA
Stall: 2.5 A

My question is, How many amps does my motor driver circuit need to be able to handle? Could I get away with a 1A driver, or should my circuit need to be able to handle the full stall amperage?


texts: How to get started with electronics and specifically cheap microcontrollers?

texts:
I have a birthday coming up and would like to try and "get into" electronics. Now seems like the ideal time to finally get enough components to get started. However I need advise choosing what to get.  I would also like to keep the cost to around £50 ($80) if at all possible.

I have coded in C before and would like to learn assembly. I have several smaller projects in mind so the microcontrollers I use would need to be £2 or less really. (I do not want to have to take the microcontroller out of the last project to make the next.) This rules out the Arduino etc. (Also that would likely be too powerful anyway.)

I have completed a GCSE in electronics. However I am still very poor at electronics and understand very little about them.

I am considering the Attiny45 for my projects as it costs only £0.50 per chip and takes a wide range of voltages; I am hoping I can simply run it off of 3 AA batteries without need for a voltage regulator. Also the Attiny range is well documented and I could easily move up to a better chip if need be. Finally it should be able to run http://www.obdev.at/products/vusb/index.html (?). Which would allow me to emulate USB 1.1 in software. I think this would be really cool.

Does the Attiny45 seem like a good choice here and are my reasons for choosing it valid?

The projects that I would like to try to make are as follows:

I would like to modify a cheap quartz clock so that it ticks in an irregular fashion. :P (While ideally still keeping time in the long run.)
I would like to control one or more RGB LEDs from a script on my computer via usb.
I would like to make my own simple intra-red remote set up with an infa-red receiver attached to the computer via usb.
I would like to see if I can modify my rice cooker to turn itself off at a slightly lower temperature so it no longer perfectly cooks the rice, and then stays on 30 seconds too long and burns it.
I would like to blink an LED to say something in morse code and repeat it over and over.
Something with SD-cards would be cool too but I think that sounds really tricky and I haven't checked if the microcontroller would be fast enough.
Interfacing with an etch-a-sketch with two motors would be very cool. Or doing a one-line plotter with two motors.
Make my own accurate clock with a quartz oscillator.

Any/all of the above sound like fun and I would really like to try and do at least 1 or 2 of them. I have absolutely no electronic related stuff at home. What should I get and what will I need? So far this is what I have thought of:

Part numbers can be looked up on the Digikey website but I can't post any more links.

I am hoping to be able to program my microcontrollers with my Raspberry Pi.
I am still missing jumper wire as I couldn't find any on Digikey. I think I will also need some transistors but I'm not sure which ones to get. Would I be able to run the DC motors with some transistors from the microcontroller?

I don't have a good soldering iron (I have one somewhere but I honestly don't think it can even melt the solder) and I do not have a multimeter. However together getting those will likely already come to £50. Do you think that they are essential to get started?

Thank you for reading. I really would be interested to know what you think is most important to get first when starting out and what other items I have missed from my list that I will need.


texts: Electronic stethoscope / contact mic not quite working

texts:
I built a circuit similar to this one here and I can hear my breathing but not my heartbeat.

Now I used this piezo from digi, and I used a FDV301n fet instead of their JFET.  Eventually I removed the emitter follower and just put the capacitively coupled output of the piezo across the 1M right into the LM386.

So the thing is if I tap the piezo it comes out loud over the speaker, and then if I hold it to my chest and hold the speaker to my ear I can hear myself breathing lightly but can't hear my heart beat.

Ignoring the possibility that I'm some kind of undead monster I figure I must be missing one of two things.   One I don't have nearly enough gain, or more likely I did not pick the right piezo element.

Could someone help me understand if I've picked a bad element and if so what a good one to use is and what the criteria I'd look for in a datasheet would be?  I don't have a lot of experience using piezos like this.  Or maybe I just need to pump up the gain.

Unless someone sees something else that's wrong here.  My end goal is build a circuit that can record a clear heart beat that I can play back later.


texts: Why are plug tops rated 16A and not 17, 18 or 19A?

texts:
In South Africa, most plug tops are unfused and are rated 16A. I would like to know how they determine what current value they'll rate a plug, and what factors influence how they rate a plug when designing it.
I know some countries use the 15A and 13A, but surely the exact value was calculated? How was this done because the information online says nothing about why the plug is rated the way it is.


texts: What type of plug do I need to switch on a VL-CSH07G LED?

texts: I ordered it from this [site][1] , and the model is VL-CSH07G. What type of power/plug/pin do I need to power the LED on ? Link to the thing I am supposed to order or its name is optimum solution here


texts: I want to add more time to this relay delay

texts:
The maximum is 3 seconds, I want it to be 5 minutes or even 10 minutes if possible.
What should I do in terms of changing capacitors or resistors etc?
Thamk you.
I tried to reverse engineer it,This is what I got:
Circuit


texts:
I was looking at the data sheet of a common 12v relay and noticed it mentioned using a resistor instead of a flyback diode for circuit protection.

On the last page for 12V models it reads;

  When connecting a coil surge protection circuit to these relays, we recommend a zener diode with a zener voltage of 24 V or higher, or a resistor (680Ω to 1,000Ω). When a diode is connected to the coil in parallel, the release time will slow down and working life may shorten. Before use, please check the circuit and verify that the diode is not connected in parallel to the coil drive circuit.

My question is how does a resistor in parallel with a coil prevent induced voltage from reaching the rest of the circuit? If we considered the coil to be a high voltage source for a moment, won't that voltage potential reach anything in parallel with it?

Or, is the resistor connected from the coil drive circuit to ground? In either case - how is the math calculated for the resistor value required?


texts:
I’m planning on building a electric bike/motorcycle and was wondering on what affects motor speed and torque.

How does voltage affect a brushed motor and brushless motor?
I would be powering this off a battery pack, if the max discharge amperage is 30A, how do I prevent the motor from drawing more than that?
If I have a 48V motor and supply a power source of 48V 20Ah, how do I know how much amperage it will draw?
If I want fast acceleration, can I somehow give more amperage than reduce the amperage and increase volts for top speed?
How do Tesla’s achieve such fast acceleration with no gearbox?

I’m sorry those are long questions. Any help on any question would be greatly appreciated.


texts: How to choose correct resistor with proper wattage and ohms for 6 leds connected in a serial circuit?

texts:
Let's suppose I've six LED lights with each 3.2 Volt and 20mA  and all six of them are connected in one serial circuit. I know there is better setup but for this I'm using this circuit setup.

I'm using a single power source with two 12volt A23 batteries kept inside a 2 battery case and a 240 ohm resistor is also present in between power source and the first LED light.

I calculated the resistance for the resistor like this using Ohm's law:

$$
R = \frac{\Delta V}{I} = \frac{24\,V - (3.2 V\, * 6\, \text{LEDs})}{ \frac{20}{1000}A}  = 240\, \Omega
$$

Power dissipated by the resistor:

$$
\text{Power dissipated by resistor} = (24\, V - (3.2\,V * 6\, \text{LEDs})) * \left(\frac{20}{1000}\right) \text{A} = 0.096 \text{ Watt}
$$

So should I buy 1/10 watt and 240 Ohm resistor for this circuit?

If my calculations are totally wrong above, can anyone kindly tell me or better if can be shown the correct calculation and the proper resistor with correct ohm and watt?


texts: Arduino ESP8266: Connecting external power supply and USB from PC at the same time

texts:
I am using a ESP8266 esp-12e NodeMCU development board. The board has 1117 regulator to generate the 3.3V required by the module. It takes input from USB cable.

When i connect the NodeMCU to my desktop computer via USB cable, i am able to upload and run the programs into it from ArduinoIDE.

But when i connect the same NodeMCU(using the same USB cable) to my laptop, i get the following errors when i try to run programs using ArduinoIDE:-

espcomm_sync failed

espcomm_open failed

I tried searching the internet and found some threads explaining that insufficient power is the cause of these errors. Which means the NodeMCU is not getting sufficient power from the laptop(i guess!!).

So i have ordered an external 3.3Volt power supply meant for Arduino based devices.

But i am not sure whether to connect the NodeMCU to my laptop as well as the external power supply at the same time??

Is it safe to do so or will it cause any harm to the NodeMCU/Laptop ??


texts: Does a shift register have a voltage drop without any outputs?

texts:
I'm still trying to get a full grip with shift registers (and mostly all of electronics), I'm building a circuit that will be run of of an Arduino at 5v, and looking to implement a shift register or two into the design. What I need to know is with 5v, how much power does that shift register use itself, and how much do I have to run two of them. I haven't seen any other questions or advice like this, so I believe it must not be asking the right thing, but what exactly do I need to know to get started?

Thanks!


texts:
According to this document on page 3, the formula for Field strength is stated as follows:

I can't find reference to this formula elsewhere and was wondering if someone can verify this is correct, in particular where the value of 30 comes from. Thanks.


texts: Li-Ion Battery Protection Circuit: Do I tie BAT-- to Ground?

texts:
I'm designing a circuit that integrates both USB Power and a Li-Ion battery when USB is unplugged. For the battery charging/protection/boost part, I'm following the schematic given in this Instructable.
The below has been completely edited to provide a more full schematic.
Currently, my project has a representative schematic like below which mostly parallels the GreatScott! schematic linked above. However, the key differences are replacing the 5V/GND terminals with an actual resistive 5V Load that draws 300mA [please assume this]. Additionally, a power line runs from the 5V of the USB [with power filtering using a ferrite bead and decoupling caps omitted] directly to the load via a schottky diode [omitted by accident], to power it when the USB is connected instead of the battery.
Note that BAT+ and BAT- on the image below (right in the middle near the protection IC block) are two solder terminals for a single-cell Li-Ion polymer battery, outputting 3.7V nominal, 4.2V max.

My main concern here is that is actually appears the BAT- terminal of the battery is never explicitly connected to ground. Thus, when USB power is removed, does BAT- ever form a complete circuit in this case? The only instance where I even see BAT- here is in teh Protection IC section [lower middle of the picture].
I'm aware that BAT+ should never be shorted to ground, since that would just be a short-circuit. However, where does the BAT- terminal go? The path of the BAT+ makes absolute sense, going into the Boost IC after a toggle switch. The BAT- connection is confusing me on the other hand.
Clearly, when USB is plugged in, the USB's ground becomes the functional GND for the circuit, and it is complete. However, the BAT- terminal never appears except right in the protection IC. Therefore, I'm confused how BAT+ and BAT- form a complete circuit w/ the load in the event the USB is disconnected.


texts: Experimental mounting for high power LED

texts:
I have bought this UV LED for experimental purposes. I do not want to go to the expense of creating a miniature PCB to mount it, but I obviously need to heatsink it. It is tiny - 3.3mm x 3.3mm and can dissipate up to 3W (when properly mounted and cooled, I assume).

Are there any shortcuts people can suggest? It is not (yet) for a production item and it only needs to work for a few hours evaluation.


texts: Fuses & current ratings - are there fuses that blow "fast" close to their nominal rating?

texts:
The context or reason for this question is the following:
Reminder: the question is about the fuse, not about the TRIAC.  The context may help to understand the question.
A 230V output is controlled by a DPAK2 TRIAC that is protected with a fuse of type F6.3A/250V 5x20mm glass type.  The TRIAC can take 8A.
A test was made with a load (heater) of 1000W (about 4 Amps).  The circuit worked fine for several hours.
Then the heater was switched to 2000W (about 8 Amps).  The fuse did not blow, but the TRIAC did.
The reason for that is that at 8A, the TRIAC has to dissipate too much heat and there is no specific cooling.  Possible 6A is also too much, but that is not the question.
Question
Thermal fuses are rated for speed with T, M or F, and are rated for a given current.  This is in fact misleading.  The fuse does not break above the given current - il requires a lot of time for a glass fuse rated at 4 Amp to blow at 4.5 Amp.
In fact the rating T, M and F are "specified" for currents that are 10 (ten) times the nominal current.
According to my analysis of the F6.3A glass fuse, at 8A the fuse will blow after about 200s.  Which leaves enough time for anything else to overheat and blow itself.
So this made we realise that glass fuses, ceramic fuses and other fuses exists possibly because they have "better" ratings with regards to overcurrent protection.
Are there fuses that would allow a 4Amp current to flow indefinitely, but blow pretty fast (say about one second) for a current slightly exceeding 4 Amps, for example 4.5 Amps.
A comparison between fuse technologies that are commonly available for PCBs would be nice but the principal information I am looking for is the existance (or not) of fuses that do what most people would expect them to do: blow in a short time as soon as the current exceeds the current rating.


texts:
I am trying to drive a 30 pF load cap (1 pF times 30 or 2pF times 15 or so on) from a ring oscillator generated clock. The frequency I want is 250 Mhz. What is the best approach to keep the input current as minimum as possible. Using more clock buffers or buffer tree draws more current while if I make a buffer by myself with cmos inverter then some spikes at edges get amplified and it screws up the current consumption at the final stage. Also less buffers results in incomplete charge and discharge of the load cap.

I pass a clock signal through some gate and then I see a small dent at the output (the reason is still unknown and it is not noise as it is periodic, i could not figure out yet) which when fed to inverters (drivers) naturally gets amplified. Now, How do I reduce the inverter gain and also if I reduce the gain then my charging of load cap gets affected, so is there a way to have minimum current consumption while charging and discharging the cap without screwing my final clock much? I know this is a stupid question but just thought if there is any solution that I am not aware of. I want to keep my input current below 500uA and the design is in 350nm technology. The load caps are for charge pump.


texts: Current in parallel circuit not increasing linearly

texts:
I have 6 parallel connected solar panels, each with the following configuration;

Max Power: 240W
Max Voltage: 30V
Max Current: 8A

According to my understanding, total current in parallel configuration should be the sum of each source, i.e. P1 + P2 + ... + P6. In an ideal scenario, it means 6 panels * 8A = 48A.

However, this is sum of current I get, when I connect panels one by one: 7A, 12A, 16A, 19A, 21A, 22A. This is only 46% of the ideal case.

P.S. Configuration diagram, with each panel enclosed in dotted square.


texts: Is it possible to use 4-pin mode for an SD card with a microcontroller instead of SPI mode?

texts: Is it possible to use the 4-pin mode of an SD card when designing an interface with a microcontroller, or must you always use SPI mode? I am particularly thinking of a microcontroller such as a PIC24. The SPI mode is slower, obviously, and I am trying to think of better ways to improve the device's throughput.


texts:
I am asking for help with filtering input voltage for attiny2313.
The schematics of the problematic board is here:

The circuit is powered by a MEAN WELL RD-125A power supply 5+12V.
There are 3 of these boards in the device each controlling one 12V 7 segment LED display.
This board is receiving data from a RPi and decoding it into a 7 segment output. The transistors are switching 12V 90mA each supplied by another output of the same power supply.
The problem we are experiencing is that random segments blink randomly when any other appliance for example a lamp is switched on/off while plugged in the same extension cord as the power supply. This is a problem for us because the device also has a relay and switches it's own 230V piezo siren causing the same blinking issue.
I think the problem is caused by poor input voltage filtering for the microcontroller. Unfortunately this is my first mcu project and I am kind of a noob. :D
I updated the schematic to this:

adding one more 1nF capacitor and an inductor into the power side of the attiny, I found similar arrangements in various datasheets.
Is this going to work? Are the values adequate?
Before you ask I know the LED resistors seem large, the LEDs use very little current, they all light up very well. :D
PCB Layouts:
This is the version that is currently having problems:

I have updated it to include the inductor and extra capacitor like this (this is not yet tested though):

The device also has separate board to which the mcu controller boards are connected:

The RPI connects to this board with the 40pin header which is split into 3 smaller connectors for 3 of the mcu controller boards. This board also has a USB connector at the top which provides power to the RPi.
All boards are connected to the same power supply and share the same ground through the Molex power connectors.
The weirdness you see around pins is because these boards are hand made and hand drilled and the extra copper helps with imprecise drilling.
The internal construction of the clock looks like this:

The two resistors on the heat sink up there are there because the Mean well power supply needs a minimal current draw. Mean well has two versions of the power supply with the same name. The new version does not need minimal current draw, the old version does need it. Unfortunately they only have the new datasheet on their website while shops still have the old version in stock.
The small board in the middle is the splitter which takes the RPI 40 pin connector and splits it into the individual mcu display controller boards. It also has the orange relay.
The siren is connected to the relay according to the layout above.
We tried shielding and grounding the signal cable which did not help.

Thanks to the comments below we found that simply connecting the signal cable even with the other end not connected to anything causes the led blinking. The cable apparently works as an antenna and picks up enough interference to influence the inputs of the attiny. We wrapped the entire cable in copper tape and grounded it to the same ground which is connected to the RPi ground and all other ground pins. That did not stop the blinking. But it confirmed that power filtering is not the problem so we decided to use the software solution by requiring the input to keep the input value for a certain amount of time before showing it on the display.
If you need to know more information about the boards or PCB layouts feel free to ask.
Thanks.


texts: Why 555 timer IC has three 5k resistances and not any other values?

texts: Why does 555 timer IC has three 5k resistors and not other values, like 10k-10k-10k or something else?


texts: Send SD data connected to Arduino to a Webhost using FTP

texts:
Sorry, I'm not very expert in drawing schematics, so this is the best I can do!

I want to connect my arduino to GSM/GPS Shield offered by Cookinghacks.com

http://www.cooking-hacks.com/3g-gprs-shield-for-arduino-3g-gps-audio-video-kit

Now, the device will be kept inside the car as a data logger. I want the device to store the location of the car, and it should also take a picture while will be saved as well on the SD card.

Now I want the system to be able every let's say 5 hours, to upload the picture and the text file containning the GPS location to an online host I've created using 3G.

How could I upload images-text files to a webserver using FTP?


texts: Reverse engineering a power supply characteristics

texts:
I have this schematics and the following information: connect the + of the multimeter to test point A and the - to test point B and read

  app. +20 VDC, 0.2 VAC

What is the RMS at the secondary of the transformer?


texts:
I'm trying to send parallel 8-bit data serially. When Send is 1, it should start sending data. It is shown in the below figure.

module transmitter(Clk, Send, PDin, SCout, SDout);
input Clk, Send;
input [7:0] PDin;
wire reg [7:0] PD;

assign PD[7:0]= PDin[7:0];

output SCout;
output reg SDout;

always@(posedge Clk)
    PD[7:1] <= PD[6:0];

assign SCout = Clk;

always@(posedge SCout)
    if(Send== 1'b1)
       SDout <= 1'b1;
    else
       SDout <= PDin[7];

endmodule

Here,

wire reg [7:0] PD;

it throws error.

  Error (10170): Verilog HDL syntax error at transmitter.v(4) near text
  "reg";  expecting an identifier ("reg" is a reserved keyword ), or
  "[", or "signed", or "unsigned"

I didn't use PD and had shifted PDin in always block before, however, it said PDin cannot be both input and reg. Therefore, I've updated the code as in the above.


texts: Input and output clamping current of the IC 4082

texts: I was reading the datasheet of the IC 4082 but I was not able to understand what are input clamping current and output clamping current of the integrated circuit. Can someone explain these terms?


texts: Trying to Understand How to connect 74LS173A in Digital Works

texts:
A little bit of background first: I found an older application that seems to be very versatile. It is called Digital Works. You can find it here.

Within this application you are able to use basic logic gates, flip flops, clocks, inputs and outputs etc, to build a circuit. Once you have the logical circuit built you can use it's template function to set pin associations from the logical part to a macro.

For example, you can use a set of gates to build a 4 bit register which is what I'm currently working on within this application. Then once you use the template tool to build the casing of the I.C. and associate the pins, you can then create this as a macro. After you are done with this you will be able to use this chip within other circuits. This is a nice level of abstraction so that you wouldn't have to build this again every time you needed a 4 bit register.

I built the logical part and tested it with interactive inputs and outputs and everything worked as expected. Then I removed the interactive inputs and replaced them with the application's tag device which is used to associate pins within the logic part to the integrated circuit.

I'm implementing a SN74LS173A Chip. I have all of the logic working. I'm now working on the outer chip (macro) part and assigning the pins. I'm trying to keep the same pin ordering as the real chip. Here is a link to the PDF of the data sheet of the chip I am building. sn74ls173a.pdf

Page 1 Shows me the pin layout which is what I'm trying to mimic when associating the pins in the macro.
Page 3 Shows the Logic Diagram in which I have completed; there are no issues here as far as the logic is concerned.
Page 4 Shows the schematics of the inputs and outputs and that they are internally connected to Vcc and Ground.

What I'm missing here; is if I go back to the logical diagram, I don't know how to run the wiring for the Vcc and Ground to create connection points for them to the interface part of the chip (macro). The data sheet doesn't show this directly and I'm a bit confused here...


texts: Inverting the logic of the inhibit pin on TI PTR08100W

texts:
I'm using this TI PTR08100W switching regulatator, and want to use the inhibit pin to keep it turned off except when I am holding down a switch.

According to the datasheet:

  The Inhibit pin is an open-collector/drain-negative logic input that is referenced to GND. Applying a low-level ground
  signal to this input disables the module's output. When the Inhibit control is active, the input current drawn by the regulator is significantly reduced. If the Inhibit pin is left open-circuit, the module will produce an output voltage
  whenever a valid input source is applied.

And indeed, connecting it to ground turns off the output.  But I want it to default to off when the button is not pressed.

Of course, the simplest solution (and the one I use right now) is to use a normally closed pushbutton switch.  But that has a couple downsides:

Normally closed switches aren't as common, so I'm a bit limited in my selection of switches.  I've yet to find tiny tactile buttons that come in normally closed, for example.
Most switches when they wear out tend to fail open, which would turn the power on, and I want the device to fail safely with power being turned off.

So how can I have it default to inhibited, and turn on when pressing a normally open switch?


texts: Output voltage accuracy vs output ripple of a linear regulator

texts: I am trying to select an LDO for powering the analog domain of a sensor that has a ripple requirement of < 50 mVpp @ 1.8 V. The 1.8 V LDO I intend to use has an output voltage accuracy of +/- 2% which means the voltage can vary by +/- 36 mV, which translates to 72 mVpp voltage. Should the output voltage inaccuracy be treated as a contributor to the ripple?


texts: I would like to know what is the purpose of ARM scatter file and ARM Linker address MAP file ?  How do they help in compilation and eventually during loading of the executable ?


texts: Superposition principle with current divider

texts:
Can somebody explain to me how can I use a current divider in a linear circuit with two current sources?

I understand that the given source is linear, so we need to apply the superposition principle. But I do not have a clear understanding of what are the steps I should follow?

I have a network below and I am asked to find U(V).

I would be also grateful if you suggest to me some sources to read or watch to understand some basics of el. eng. I am a very beginner, so if sources were without any water, just everything the most important, it would be great.

Thanks in advance :)


texts: How these circuit diagrams in the datasheet was made?

texts:
I've seen so many IC datasheets, and so appreciate the elegant reference circuit diagrams they've made. I'm not meaning the 'function' of the circuit, but the 'beautiful' schematics itself, such as below.

This picture is copied from TI's datasheet. I love it's style. I know there are so many software can draw schematic, but i've never seen any software can done this, particularly the comment style.

If someone know how to draw this, or what software can generate such schematic.


texts: Is it possible to add an existing IP variant to a Platform Designer/Qsys system through TCL?

texts:
I have a .ip file that contains a parameterized component which I'd like to use in my Qsys system. I can add the component via the GUI but I would like to be able to add it via TCL or another scripting mechanism if possible.

I have looked through the following Platform Designer documentation:
https://www.intel.com/content/www/us/en/programmable/documentation/jrw1529444674987.html

but found no way to do this. Is what I am trying to do even possible? If it is, how should I go about accomplishing it?


texts: I bought a multimeter with attached leads. I would think red is positive but when I take a reading it only works if I use black as positive. Was it assembled wrong? There's nothing in the manual. It's a greenlee dm-20.


texts: When I design a printed circuit board, I often put 100mil male header anywhere. Sometimes I think it would be better to place some connectors for more reliability. Anyone here knows which connector/crimp/tool combination is good and cheap? I recall that some of the Molex crimp tools are 200-300$ range and more... a bit too pricey for me. So I'm looking for a connector series and the associated crimp tool.


texts: Design of a counter that stays in each state for x clocks

texts:
Suppose we have an 8-bit counter out[7:0]

It needs to stay in each count for specified number of clocks x, where x can be any integer or fractional factor of 512.

My Approach:

Use 10 bit counter temp[9:0] that increments on every posedge clock

For x=512, increment temp in steps of 1, and increment out when temp[9]==1

For x=256, increment temp in steps of 2, and increment out when temp[9]==1
....and so on.

My Question

Does anyone have a better idea than this, more resource efficient?
How to handle the case when x can take arbitrary values not necessarily related by factors of a particular number? We only know the max that x can be.

To clarify: x is just a normal 9 bit register. The value in x and number of hold clocks are related by 512/x = HoldClocks.

512/1 = 512
512/2 = 256
512/3 = 170.667
512/4 = 128
........
512/512 = 1.

How about the general case? What if max hold clocks isn't a power of 2? How would you handle the case where max hold clocks (x=1) is e.g 460 instead of 512?


texts: Efficient way to get multiple Analogue voltages out of a microcontroller?

texts:
I've read in my research that most microcontrollers are not built with DAC outputs as they are expensive to include on silicon chips. Also applications that require analogue outputs typically need a higher resolution than is feasible on a microcontroller and would probably use a dedicated IC anyway.

I am planning to build an analogue synthesizer with patch memory(storage and recall of voltage states). Apparently these functioned by reading the voltage of an analogue potentiometer into a microcontroller and applying a control voltage to the synthesizer using a DAC. This state could then be saved and recalled as 'presets'.

What I would like to know is a suitable way to control multiple analogue outputs to a circuit from a microcontroller.


texts: What is the Relationship between Magnetic Flux density and electric field intensity

texts:
I was given this question by a teacher and I have scoured the internet for a formula or solution to this question, all to no avail, the question says
"in a certain region of space, the magnetic field has a value of 1 x 10-2 T and electric field has a value of 2 x 10-6V/m, what is the combined density of the electric and magnetic field. With E0 and U0 given below" !


texts: Replacing a Lipo phone battery with a li-ion battery

texts: Is it okay to replace my worn li-polymer 3.8v and 2200maH battery with a li-ion battery with 3.7v and same 2200maH capacity?Will the 0.1v be of any harm to the delicate electronics of the phone?


texts: I'm trying to build a BLDC ESC using stm32f405 and DRV8301. I'm able to generate PWM signals from STM32f405 but unable to detect the same PWM signals on the outputs of the DRV8301.I'm using a bench power supply and supplied upto 25V, Enabled the EN_GATE Pin. Please let me know if any other configurations have to be enabled to make the DRV8301 IC to work


texts: Why would a wrist watch lose power just weeks after replacing the battery?

texts: I have a CASIO watch that required a battery replacement 6 years after I got it as a new watch. Now, the replacement battery, a CR2025 cell, was installed by a jeweler and lasted 3 months. Nothing was wrong with the power supply for the 3 months. When the replacement battery stopped keeping the watch running, it may have happened while the watch was lying down, off of my wrist. Just a few weeks ago, the same watch lost power supply after taking it off before taking a shower. This time, the screen went blank, a month after the battery was replaced. No timers were on at the time. What could be the cause of this occurring? Could the problem be related to the contact between the battery cell and the connection inside the watch being loose?


texts: 230VAC to 230VDC converter for flicker free LED construction lights for use in videography/photography

texts:
We use LED construction lights for illuminating a photo or video set. As espected the lights flicker with the mains frequency. While in some cases this can be compensated with the right camerasettings it would be a lot easier if the flickering could be removed.
The lights have total of 100W at 230V/50Hz.
Osram LED worklight 2x50W

So I started out with a simple idea. A full-wave bridge rectifier with a smoothing capacitor. I had 22μF/400V capacitor and a 2W08G rectifier. The lights already flicker a lot less but the capacitor would need to be bigger of course.

A larger capacitor will result in a smoother DC, hoever that DC is still close to 325VDC which means way more power for the LEDs. Since I have no idea what, if any, electronics the lights have inside (I can not open them without likely breaking them), I do not know if thats an issue. I mean the lights have to deal with that voltage and current at the top of the sine curve, but only for a brief moment. With 325VDC I would expect the lights to get way hotter than allowed and eventually fail.

Questions:

Are my assumptions correct so far, or can I go with this simple solution for this application?
If I can go with 1., do I need any extra restiors to protect the rectifier and/or capacitor?
Is there a cheap (no more than 30€) and size wise small (<25cm³) solution that would give me a somewhat stable 230VDC? (I can't find any ICs that can deal with that kind of voltage.)

Addendum 1:

all LEDs are on when behind the rectifier, so I guess the lamps already contain a rectifier inside, just nothing to smooth the waveform


texts: Redpark cable for arduino, any alternative

texts:
I'm trying to interface my Arduino and iPod. If I use my Apple USB female connector and I buy a usb2serial cable ($5), can that combination work in place of this Redpark cable ($59!!)?

Redpark cable


texts: Which is the best way to get 16-channel simultaneous sampling ADC interface with an FPGA (Zedboard)?

texts:
I have an application that requires me to measure the amplitude of 16 different one-shot pulses (on 16 different lines) simultaneously with an FPGA (Zedboard). For each pulse, the pulse width would be 6us (so I believe a 1MSPS sampling per channel should be sufficient) with a rise/fall time of 155ns and 90ns respectively and the height of each pulse would be between 0 and 1V.
Now since I am completely new to FPGAs, I am not able to decide on the type of ADC interface (and hence the optimal ADC) I could successfully use to achieve this goal. I have thought (with my very limited FPGA knowledge) of four options (and a few ADCs) that might (or might not) work:
1.Using two 8-channel simultaneous ADC in synchronization to sample all 16 channels simultaneously. I chose AD7606C-18 (1MSPS on all 8 channels) and thought it could be used in two ways:
1.1 Use both ADCs in parallel mode (as described in CN0148 for a very similar AD7606 ADC). This would require 18 pins just for the data alone but probably require slower signaling/control to maintain 1MSPS per channel.
1.2 Use both ADC in SPI mode with two independent sets of SPI bus (clock, data, chip select) going to the FPGA where two SPI master controllers are implemented. (Question 1.2) In this case, Is it possible to instantiate two SPI masters with two separate fast clocks (not sure how fast, but should be fast enough to get 18-bit data from 8-channel each, for two ADCs) in the FPGA to get 1MSPS per channel?
2.Use 16 single-channel ADCs in SPI Chip select mode (connected SCK, SDO lines) with different SDI lines being used as Chip select. The ADC AD4007 is a single channel 1MSPS sampling and this method is described on page 33 of the datasheet. (Question 2) Will I be able to use 16 ADCs in this mode and still sample at 1MSPS per channel? How do I know how fast the SCK needs to be (and even if it possible to go that fast) so that all channels sample at 1MSPS each?
3.Use 16 single-channel ADCs in SPI daisy-chain mode with SDO forwarded to the next SDI (single-connected SCK). The ADC AD4007 is a single channel 1MSPS sampling and this method is described on page 35 of the datasheet. (Same as Question 2)
My ideal solution would be the one that:
a) (Obvious) Is feasible for 16-Channels and for measuring the above pulse parameters.
b) Requires the least number of wires if possible (so that I don't use too much FPGA IO)
c) Requires low-frequency signals (SPI clock line or other read lines) if possible (so that I can relax my PCB design).
I understand that b) and c) are somewhat mutually exclusive hence I am asking you guys to point out the optimal solution (a tradeoff maybe?) and also point out the positives/negatives/feasibility of each of the above solutions. You could also point out the best solution (even if it uses just b) or just c) ) If you want you could post a different method of your own (or suggest using a different ADC, although I think the above 4 methods pretty much cover up everything).
If the question is off-topic then if possible please pass along some helpful advice as comments. I really appreciate you taking the time to read my post. Thank you for that.


texts: Can Decimation be used to improve the SNR of a signal?

texts:
While researching SNR improvement techniques, I came across many techniques, mostly the application of digital filters and windowing. Shortly, I read an article that said that performing decimation can be used to improve the SNR of a signal, by a factor of 3dB (half in linear terms) for every time the decimation is doubled.

From my understanding of decimation, we basically throw away a certain portion of samples for every few samples taken, meaning that if we have a decimation of 3, we only keep 1 of every 3 sampled, discarding the other two.
Would it be possible for anyone to explain to me, whether or not this is true?
Can decimation be used as a SNR improvement technique? And if yes, why?

Edit: I forgot to mention that I also read that decimation first applies a low pass filter, before discarding the samples. Is this true? And if yes, how would this be implemented? Would this be the construction of a (digital) FIR filter?


texts: What happen if 0 and 1 are transmitted simultaneously with BPSK?

texts:
I'm just curious that  what happen if 0 and 1 are transmitted simultaneously from different source nodes to an equidistant destination node with BPSK? Assuming perfect signal shaping, synchronization and equidistant.

I think it can be expanded to higher modulation scheme sending two totally opposite symbols.

In my opinion, they are cancelled each other and the destination can hear only the noise. Maybe, I have a wrong knowledge of signal superpositioning on the air.