texts: Is it bad to turn off IC by connecting its Vcc to ground?

texts:
I am using NTE74141 chips to connect the cathodes of nixie tubes to ground. To spare some Arduino pins (which I connect to the inputs of these ICs) I would like to multiplex the tubes. One idea was to simply make all inputs of the ICs the same, and essentially turn on and off the ICs by connecting it's Vcc to ground using a different Arduino pin.

This setup seems to be working fine, but my question is: is it damaging for ICs to connect it's Vcc to ground, and if so, why?


texts:
I'm trying to understand the transfer function of the band pass sallen key filter, which looks like:

With the following circuit:

How can I analyse it to get the transfer function? Thanks for any help.


texts:
After skimming through this article, I am wondering what are the benefits of SWD debugging over JTAG debugging?

I understand SWD uses less wires/pins, takes up less space etc. But how does it play out in terms of performance, features and cost of the hardware programmer/debugger devices? Can code still be break pointed/paused and stepped through in IDE's like Eclipse?

Can an ARM chip be programmed using the SWD interface, like I believe can be done in JTAG?


texts: What is the impedance looking into a length of coaxial cable that is short-circuited at the far end and a half wave-length long?

texts: What is the impedance looking into a length of coaxial cable that is short-circuited at the far end and a half wave long? I have been told that this the the basis of what is known as a wave guide "Choke Joint" can someone explain the usefulness of having such a device in a waveguide, of all places, which is meant to transport signals from point a to point b in the most efficient manner possible?


texts: Trailer Light Conversion Module Not Working

texts: I have a module with the attached schematic that I'm testing.  On the left is the "vehicle" and the right is the "trailer"  I don't have a load on the left side just inputting straight voltage.  On the right I have attached a LED bulb and have tested with no load, but either way I'm not getting any output on the "trailer" side.  Do I need to have a load on both sides?  I've tried 2 modules and get the same results on both.  Just want to have the turn signal function no matter if the brake is on or off, which is what I believe this circuit should do.  Thanks in advance.


texts: Genlock two OV5642 camera modules on Arduino with ArduCam

texts:
I need to shoot stereo video or stills at about 10 FPS possibly in perfect sync. My plan is to set up a 3D stereo rig (2 standalone units - each consisting of Arduino UNO + ArduCam shield + OV5642 camera module) an then fire both units via single remote shutter. Such a setup might already result in a pretty good synchronization since the hardware is very simple, but I was told in this post that I could probably do real genlock - sync both OV5642 modules with an single external clock signal fed from oscillator. This would likely result in a 100% frame synchronization.

According to this datasheet (corresponding eBay item) the OV5642 supports "external frame synchronization in frame exposure mode". I am not sure if "frame exposure mode" means still imaging only (no video?) - I do not mind this since I will rather work with still image files than with video file. Is it correct that I can do a single genlock for both cameras? If so, could someone please tell me how exactly this can be done?

My hardware building/hacking knowledge is close to zero though, so I prefer an easy solution. I am not sure if the oscillator signal can be fed from one of Arduino boards or whether it needs to come from other external source. A major plus of the solution will be low cost and use of small embedded hardware (no big boxes needing lot of power) so that can be used in mobile environment.

The application of my stereo will be mobile road/terrain 3D scanner in a passenger car moving up to say 100 km/h - another issue could be rolling shutter and I understand I wont get global shutter cheaply. I hope on short enough exposure time to minimize rolling shutter or simply on reducing vehicle speed. Sure I could get a global shutter sensor but I am poised to explore the low-cost way first.

In case someone know about a similar solution (in terms of size and cost) using another hardware altogether (camera etc.) I will be happy to hear about it.


texts: AC-DC Switching Power adapter Unstable Voltage

texts:
I recently bought a AC-DC (14V DC, 3A) Power Supply on eBay to power a Samsung Monitor, and it does power on my monitor. It is not the monitor because another power adapter I have works with it.

Using a multimeter, the output voltage is unstable going from ~14V to ~13V repeatedly. Is the output filtering capacitors bad, or is it a switching mosfet that is bad?


texts:
I made the following program for displaying no of days in the user provided month. And to check whether the year user entered is leap year or not. I am trying to make the program on data flow level. I don't know whether I can use if/else in data flow level in Verilog. The following program is giving me errors at the notified place.

module LeapYear(year,month,leapOrNot,Days);

input year,month;

output leapOrNot,Days;
 // error here
      if((year&400)==0) && ((year % 100)!==0 || (year & 4)==0)begin
       leapOrNot=1;
       end
  else

if(month==4 || month==6|| month==9|| month==11)begin
    Days=30;
end else
    if(month==1 || month==3|| month==5|| month==7|| month==8|| month==10|| month==12)begin
         Days=31;
  end  else
        if(month==2 && leapOrNot==1) begin
            Days=29;
     end   else begin
              Days=28;
              end

  endmodule

Please tell me what is the reason for this error.
There error is

 ** Error: C:/Modeltech_5.7f/examples/LeapYear.v(9): near "if": syntax error

Regards


texts: Can I convert L-ion battery backup to supercapacitor?

texts:
I have a RAID card in my home server and the battery went dead. It's a lithium ion chemistry with the circuits to tell the RAID card miscellaneous information. I could buy another L-Ion battery to solder in there, but I'd rather upgrade to a supercap for about the same price.

My question is. What kind of affects would I get from just soldering a cap in place of the L-Ion pack? Will the charging circuit work? At the end of the day, the cap should be better than the l-ion pack in all regards, right?

Note: The charging circuit limits current to 500mA


texts: What determines the frequency of network cable

texts:
You have Cat6, 23 AWG, rated for 250Mhz frequency. You then have Cat6a, 23 AWG, rated for 500Mhz. Both are unshielded.

How is Cat6a able to transmit data at a higher frequency then its counter part?

They are both the same gauge wire, same copper, but one is rated faster. How?


texts:
As the title says I am looking to run one 3 Watt RGB LED off of 3 AA batteries. I am planning to control them with an Arduino using TIP122 transistor. What I am worried about is not being able to supply enough power. HERE is the LED I am looking into getting.

My current plan is to use 3 AA batteries in series to get 4.5 volts and power the LED's off of that. Is this correct or do I need more/less voltage? I am also worried about the batteries dying and slowly losing their voltage. Could this damage the LED's? And my last question is in videos like this he uses a 42-ohm resistor between the transistor and the battery. What resistor would I use?

Thanks for any assistance.

[EDIT] I am using alkaline AA batteries

[EDIT 2] I found these batteries that might be better suited for this project instead of normal AA batteries

[EDIT 3] As requested, the purpose of this project is to control a high powered rgb led. I am using an arduino uno to control it because I will need to be able to have PWM control of the RGB values; however, I do not have access to a wall outlet. This needs to be able to run off of battery power. Also I am trying to keep the cost of the project down and don't want to spend a ton of money.


texts: What is the difference between RS-232 and TTL UART?

texts:
I always need to communicate with the TTL UART port on the MCU with a computer. When I talked about that, people always refer the UART port as an RS-232 port. Are they correct? If not, what is the difference between them?

Also, can I use a RS-232-to-USB converter for a TTL UART port?


texts:
I can't find the size of a page of memory in an STM32L0 (specifically STM32L053R8, see DocID 025844).  I don't see a referenced as to the size of a page of memory.

Note:  This is also in reference to the native boot-loader.


texts: How to use motor drivers with H-bridge and PWM input, to control direction and speed of DC motors?

texts:
I'm running series of experiments using a 6V DC motor. I'm using desktop DC power supply to power the motor and regulate its speed and everything works just fine, the setup has been running for months.
Now I need to use Arduino motor shield to power the motor and run a particular control sequence (involving motor speed, direction, brake). Arduino is powered by 9V DC supply brick (from an 110V outlet), and delivers approx. 8.5V on its outlet power pins. Once I connect the motor the voltage I read on the pins is approx. 6.8V using my multi-meter. I cannot measure the current, once I connect the multi-meter the RPM drops dramatically, I guess I'm affecting the circuit somehow.
So far i have been using Arduino's PWM control successfully but only for motors rated for voltage equal or greater than that of the power supply. This time I'm conscious of the max. voltage/current on/through the motor. I understand that PWM will reduce the average voltage but my understanding is that the motor will see the full voltage only at shorter intervals. Will this damage the motor? Playing with different PWM values I was able to get the same voltage as previously from bench DC power supply (say, 3V) but the motor noise is quite different. Motor is much louder and it sound as if it's struggling to work. I'm still measuring the same average voltage of 3V on the motor's power pins. I'm afraid this will reduce motor life or burn it completely if I continue letting 6.8V (8.5V?) directly onto it. How safe is to continue this operation?
I also saw a good discussion on regulators here on StackExchange. If PWM is not suitable, should I try a voltage regulator? Ultimately, what I'm trying to achieve is for motor to change the speed/RPM but also the direction - not sure if I can pull this off with the regulators. What would be your advice for this application?
Please don't mind if I used inappropriate terminology - I'm just a daft mechanical guy trying to figure the electrical part of how I can run this safely. I'd appreciate any input. Thanks.
EDIT: This is to provide info on PWM frequencies/mark/space ratios. I hope a chart is OK, it might be easier to explain.
The way Arduino works is you set PWM via a byte, so sending a value between 0 and 255. 0 will let no marks through, 255 will have no spaces.
I plotted here the voltage measurements across motor contacts when: a) no motor is connected, b) when motor was connected and rotation was set to CW, and c) when motor was connected and rotating CCW. CCW rotation voltage should have "-" sign in front but I plotted it this way to be easier to read and compare. Motor had no mechanical load on it.
For the motor, I stopped plotting PWM at point when I almost reached the rated voltage. I'd like to run the motor at minimum of 2.5V, and I'm interested to know how high I can go. Also if this minimum is OK or not (so far it worked just fine off of a bench DC supply).
I hope this makes sense and please let me know if there's anything else I should check and provide.


texts: Biasing network for phototubes and photomultipliers

texts:
I have some doubts about typical biasing network for vacuum phototubes and photomultipliers.
Precisely, let's start by a simple photocathode.

I have seen some biasing network like this one:

In this circuit, which is the precise role of \$R_L\$? I'd say it is a current to voltage converter, but I was asking if it may have also another role. For instance, if the phototube were a diode, that resistor would be useful to establish the correct current along the diode. Has it this role also in this situation?

In this picture there is another type of circuit (like the previous one but with a DC blocking capacitor). In the image of the real tube, it seems that the anodic resistor and the DC blocking  capacitor are already inside the tube. Is it correct, or should the customer add them externally to the tube?

Finally, this is a photomultiplier

I'd say that the logic behind this biasing network is simply that of using a high anodic voltage between anode and cathode (like in a simple phototube), but with also some voltage dividers in order to get smaller voltages for the intermediate electrodes. But I was asking if it is exactly a voltage divider: is the current across each intermediate electrode low, so that we may consider that network a voltage divider?


texts:
I'm trying to figure out the corner cases for verifying a synchronous FIFO during hardware verification.

My setup is a very simple two ports synchronous FIFO (write/read) and the write clk frequency is same as read clk frequency.

In order to test whether the FIFO overflow occurs or not, can somebody help me identify those corner cases so that we can completely verify this simple synchronous FIFO?


texts: How to calculate the Time Constant (tau) for a digital circuit

texts:
I'm trying to find the time constant of this digital circuit. It's one of the first digital circuit I'm dealing with, so I don't really know how to deal with logical ports.

What would be the equivalent impedance of this circuit and how to find it? I know the basic rules to apply to find it (turn off current/voltage sources) but I don't know how to do it when logical ports are present.

Thanks!

simulate this circuit – Schematic created using CircuitLab


texts: MOSFET symbol - what is the correct symbol

texts: I've been on this site now a couple of months and I notice various symbols used for MOSFETs. What is the preferred symbol for an N Channel MOSFET and why?


texts: Estimating actual capacitance for aluminum electrolytic capacitor in buffer application

texts:
Application:
In a capacitor power buffer application it is preferable to have higher voltage over the capacitors to increase the energy density, as the energy E in a capacitor is given by $$E = \frac{1}{2}CV^2$$

The capacitor voltage should thus be above the nominal voltage for the system to get higher energy density and smaller physical volume of the buffer, which then requires an input step-up converter and an output step-down converter as to charge and discharge the buffer.

Problem
Now, one of the energy challenges is the switching frequency of the step-down converter, seen as a ripple current at the buffer capacitors. When the buffer is active and providing hold-up, the stated capacitance for the capacitors is effectively de-rated due to the frequency of the ripple current.

Question
For an aluminum electrolyte capacitor and a ripple current of 1 A @ 100 kHz, how is the actual (available) capacitance estimated?

E.g. for the Vishay 250 CRZ-V series, the capacitance vs frequency is given in the graph below. The stated capacitance is thus reduced by ~ 60% at 100 kHz for the 63 - 100 V caps.

However, most datasheets does not provide this graph. How is the actual capacitance estimated in those cases? Is there any actions that would counter the reduction of available energy other than lowering the switching frequency?


texts:
This three-part question is algebraic and non-numerical in nature so as to be rigorous and the transferable.

Part one

How does one model a transformer in a circuit? Take the following rudimentary schematic.

Would this be equivalent (for linear operation) to

where \$L_1\$, dependent source \$V_T\$ and \$L_2\$ represent \$T_1\$?

\$L_1\$ and \$L_2\$ are ideal components which should in practice have ac resistance, dc resistance and interwinding capacitance.

If so, is the calculation of \$V_2\$:
$$V_{L_1}=V_1 \cdot \frac{j \omega L_1}{R_1+j \omega L_1}$$

$$V_T=\frac{Z_S^2}{Z_P^2} \cdot V_{L_1}$$
$$V_2 = \frac{R_3}{R_2 + R_3 + j \omega L_1}
\frac{(j \omega L_2)^2}{(j \omega L_1)^2}
\left(V_1 \cdot
\frac{j \omega L_1}{R_1+j \omega L_1}
\right)$$

Follow-up: Is it the ratio of the inductive impedance which gives the transformation of voltage or current, or does the non-ideal inductor ac-resistance, dc-resistance and interwinding-capacitance also count in the formulae
$$\frac{Z_S^2}{Z_P^2}=\frac{V_S}{V_P}$$

Part Two

How does the the impedance of the circuit attached to the secondary coil affect the primary circuit

impedance
current
phase

Part Three

If the Phase of the voltage source \$V_1\$ is zero (\$V_1 + j 0 )\$, what would be the phase of the voltage and current in the secondary circuit.

Regards

Daniel


texts:
We have two 80 A motor controllers running on a 55 V lithium battery. Our current isolator is rated at 300 A. Our motor controllers typically draw 40 A under load.
We are having issues with the isolators prematurely failing due to contact arcing, presumably due to the high voltage DC and the motor controller inrush current.
The battery isolator is cycled on average 10 times per day, whilst not in use and to change over batteries.
The motors are stopped using the motor controllers and therefore the isolator is only used at zero motor current. We have observed a large inrush current as there are 4 x 4700 uf capacitors.
We have tried a number of isolators, including a Flipsky anti-spark switch. We attempted a high-value resistor to pre-charge the caps. Whilst this worked, it required the user to hold a "charge button".
With your help and advice We are now in talks with Allbright to spec up a suitable contactor and using a programable timer to turn on the contactor, a suitable sized fuse will protect the resistor should the contactor fail to close.

https://www.arc-components.com/sw180b-8-albright-single-acting-solenoid-contactor-48v-continuous-6644.htm


texts: Toroids low magnetic field is only for the core?

texts:
Here is a thing. When I connect it as 120v (parallel), the magnetic field outside the core is much lesser than when connected as 240v (series). The load of both is same 100v-256v autovolt LG OLED TV (just for testing).

Does it mean when connecting as 240v series, the windings don't have uniform current? Why? How?

It's for this model http://catalog.triadmagnetics.com/Asset/VPM240-2080.pdf, a 500va medical isolation transformer I bought to protect my bench project troubleshooting.


texts: Is it safe to program a Pololu 3pi robot from Sparkfun without batteries, using only a power supply from the AVR programmer?


texts: I am having a problem where my MOSFET instantly starts conducting when I connect a power supply. I have the gate signal from an Arduino Nano, which is tied low. I am nearly 100% sure I have the drain and the source wired correctly. I have created somewhat of a rough schematic which I have provided also. The load draws A LOT of current (8A). I'm not sure what is causing this. Any input would be greatly appreciated.


texts: Driving a small water pump with a microcontroller and a transistor

texts:
I have bought some water pumps for a project I am currently working on, the thing is that I have never used water pumps before, I am sure that pumps are inductive loads, but I am unable to know the Inductance of the coil inside the motors.

The pumps come with some information written on it.

Mini Water Pump JT-DC3W
Supply: 2.5 - 6 V DC
Current: 130 - 220 mA
Power: 0.4W - 1.5 W
Water Flow: 80-120 L/Hour

I would like to drive these pumps without any relay, if it is possible with some To-92 BJT. I know that as the pump is an inductive load a proper flyback diode should be added.

How can I model the pump's coil with the data provided?, also what kind of BJT can I use, one that at least can take 300 mA?, wouldn't current spikes burn the BJT?

This the schematic I have in mind:


texts: What is difference between IBIS model and IBIS-AMI model and what are specific application of these two models?

texts: I am working on PCIe 3.0 compliance testing from signal integrity and power integrity point of view. I would like to understand the difference between IBIS and IBIS-AMI model and which model is good for my simulation? These models are used in transient and channel simulation of PCIe 3.0.


texts:
I'm designing a MOSFET (FQP30N06L) circuit to drive a (50V, 3.4ohm) pinball solenoid controlled by a PWM pin on an Arduino DUE:

simulate this circuit – Schematic created using CircuitLab

The MOSFET gate and solenoid are tied to the terminal block to make external alterations easier. My concern is that, while altering the circuit I will forget to ground myself, and fry the MOSFET. My understanding is that when MOSFETs fail for this reason, they often become shorts which would fry the solenoid coil very quickly.

My question is, what can I do in-circuit between the terminal block and the MOSFET to protect the MOSFET from ESD?


texts: Line, Neutral and Ground and another Ground

texts:
I try to make a 110VAC energy meter connected to my computer out of the CS5490

This IC measures voltage and current over a voltage divider and shunt resistor respectively and then calculates the power. Besides connecting the measure inputs, the IC also needs power. In a stand alone metering application this power needs to come from the same line and that is the example they give in the datasheet. But in my case I have an external power supply that I would like to use. Also I think (correct me if I am wrong) one should not connect the Neutral from the line to the ground from a PC.

Fig 21 on page 54 of the datasheet is then plain wrong?

What is the correct way of doing this? Can I do it without the need of adding another power supply? And what does a pointing down triangle mean compared to the more usual ground symbol?

It's an awesome group of EE's here, any help is highly appreciated!


texts: PCI express devices are required to support MSI: what does that mean?

texts:
I am a bit confused concerning an issue I had with a PCI Express (PCIe) card used to interface serial device on a Linux computer. The card is based on the XR17V354 chip from MaxLinear.
From the beginning, the card was correctly recognized by the OS (it was listed in the lspci output), but reading and writing to the serial device (/dev/ttySx or /dev/ttyXRx) failed, no matter which driver was used (8250 serial driver built into the Linux kernel or device/chip manufacturer driver).
Now, I eventually traced back the problem to an interrupt issue: interrupts were correctly raised on the card (visible by polling the UART ISR register and also in the PCI INTx register), but never "reached" the CPU (counter in /proc/interrupt stuck at 0).
The issue was solved by disabling MSI (Message Signaled Interrupts), by adding pci=nomsi in the Linux kernel command line parameters.
Now, this is the part that confuses me:

I read that PCIe devices are required to support MSI

PCI Express permits devices to use these legacy interrupt messages,
retaining software compatibility with PCI drivers, but they are
required to also support MSI or MSI-X in the PCI layer.

In the chip datasheet and also in the lspci -v output, I see that there is an entry in the PCI Configuration Registers for the MSI capability (MSI Capacity ID = 0x05).
However, all the associated registers (eg Message Control Register) are Read-Only... which explains why MSI is not working and I had to disable it in the OS so it would handle INTx interrupts raised by the device

Does it mean the device is "broken", ie not compliant to PCIe requirements?
Or does the MSI support required from PCIe devices just implies to have a MSI Capacity ID (0x05), but doesn't actually require to implement the MSI feature?


texts: Why does my synchronous up counter count enable not function properly?

texts:
I have designed a simple 4-bit synchronous up-counter, using master/slave JK flip flops in Logisim.

Here is my JK design:

And my counter design:

It works perfectly as intended, however if the INC (count enable) is toggled to 0 while the CLK pulse is high - it doesn’t actually stop the count. Each successive clock pulse still increments the overall count, even though INC/count enable is now 0.

However, if INC is toggled to 0 while the clock pulse is low, it does indeed prevent the count from increasing. Am I missing something in the design?

I’ve tested this exact layout in other simulators too, so it’s definitely a flaw in the logic.

Note - PRE and NOT Q are the two unused pins on each JK chip in the counter circuit.


texts: In designing a digital filter by impulse invariance method why is the scaling factor irrelevant?

texts:
I've come across a few examples that the scaling factor T in the eqn below can be arbitrarily chosen as unity. How is that possible? doesn't T have something to do with the Nyquist sampling rate?

\$H(e^{jw})\$ = \$1/T\$ * \$\Sigma H_a(jw/T - j2k\pi/T)\$


texts:
(well. I am NOT speaking of "virtual ground" throughout this question/)
As this figure has shown an opamp can be viewed as:

We all know that an opamp like this has two inputs and one output - the input voltage is simply the voltage between the two inputs - but for output voltage, it looks like (from the figure above) there is a "ground" symbol inside the opamp.
Since the opamp does not have any ports connected to the ground (the real Earth), what that "ground" symbol is? This answer gives a good explanation, showing that "ground" is actually the negative electrode of the DC supply (The -Vsupply in the figure above).
(Wait! Don't mark it as duplicate. Read ahead.)
But this is just where my question emerges - Because one thing I know is that most DC power supplies are not grounded to the real earth - i.e. they are floating. Therefore, we do not know what's its voltage referring to the real Earth. Maybe at the negative of DC supply, it is still having, say, 1V voltage referring to the real Earth.
This is all okay until we ground (to real Earth) the non-inverting input and connect the inverting input to the output to form a negative feedback circuit. i.e. the image below

Then when there is a voltage between the two inputs, the output will produce voltage. But WAIT... That output voltage is not produced regarding the real Earth - but regarding the negative of the floating DC supply (As the linked answer and previous explained)! That is if the -Vsupply still has a 1V voltage regarding the real Earth, the output will always plus 1V regarding the real earth!

Well, I also did experiments regarding this question that has confused me for more than a week. I did not encounter such problems at all, because even for the floating DC supply, it still maintained a good zero volts referring to the ground (real earth)... I don't know why a floating DC power supply can work that good, just like a grounded one... (Why? please tell me why) - But after all, it is floating - which means there is no guarantee that the negative side of the DC supply is always exactly 0V referring to the real earth...

I am quite a noob in electrics.. Is there something that I have misunderstood above? Indeed, the concept of grounding and floating seems hellish hard to me...


texts: Dual polarity power supply for project, possible choices?

texts:
For a variable power supply I require 15V to get ~0-12V, and +/-15V for an op amp as part of the project requirements, also negative rail in the future.

Two plugpacks (isolated, 15/0/-15)to me seems expensive, cannot find many that are 15V that are rated for 1A and so I am out of luck it seems.

I am looking at a transformer even though I am worried about touching them. I've found one that is 20VA with a secondary of 16V, if I am correct, 20/16=1.25A which is above my 1A limit for the power supply even though I am not likely to go up to that.

I may buy something like an IEC plug jack as computer supplies have so I have nothing exposed until the inside, and wire up the transformer there.

Are there any alternatives to this that come to mind? I would rather not touch mains unless required, however plugpacks just seem too limited..


texts:
I have a doubt. What does it mean to get a convergence error in simulation?
What does it actually mean and how can it be eliminated?


texts: Where can I get informations about smartphones battery datasheet?

texts: I'm hardly trying to find the datasheets and I still got nothing :(, what I was try to find is like Asus battery for Zenfone 4 Model: C11P1404 datasheet. Please for your kindness tell me where can I find that one :)


texts: Is Cadence unable to simulate AC to DC converters using simple full bridge rectifier?

texts:
I've tried several different topologies, such as the full bridge rectifier and the following which I've successfully tested on other simulators.

However, on Cadence I always end up getting static like this in the output...

Just be honest. Is it me? Or is it Cadence.

Edit:

Here is a picture of the circuit in Cadence.

Here is a picture of the output run from 0s to 3750us.

Here is a picture of the output run for 3s total.


texts: What is input capacitance of pins in IC and what effect does it have?

texts:
What is the purpose and the definition of the input capacitance parameter in the datasheet.

I have tried to research about this topic but was only able to find the input capacitance parameter with respect to operational amplifiers only. Even after those research, I was not able to understand the concept of input capacitance with respect to this buffer IC.

Can someone help me with my following queries :

What is the definition of input capacitance of a pin in an IC?
How is it measured in the first place and is it applicable to all pins in the IC? I am sure, different pins of the IC must have different circuits connected inside. So, the input capacitance of those pins might be different.
Is the input capacitance parameter relevant only to supply/signal pins?
Why should we care about this parameter of the IC while we design our circuit and how is it relevant?


texts: Can we do source transformation for dependent sources?

texts: In network analysis, during source transformation for dependent sources


texts: If the High Pass Filter is a differentiator, what's the analogy for Low Pass Filter?

texts:
I have seen many times the analogy that the High Pass Filter (HPF) is a differentiator, something that explains some interesting facts, like that a non-negative signal might have negative components as in the case of differentiating a positive signal.

1) Is there an equivalent analogy for the LPF? How about the BPF?
1) Is there a mathematical formulation that prove these results?


texts: Difference between body, bulk and substrate?

texts: I have a pretty fundamental question related MOSFET devices. I am confused about whether the terms body, bulk and substrate are all just names for the same thing or are there actually some differences between what each is referring to ? I feel like I have heard them all being used interchangeably to describe the same thing.


texts:
Can someone explain in simple terms how a delta-sigma modulator works specifically for ADC applications? I've googled around and have been piecing it together but am still unclear on a few things.

Most descriptions note an accumulator with a certain DC offset that affects ADCs oscillation but I don't understand what is being accumulated/what is oscillating/ what threshold these are referring to.


texts: CAN communication design/definition between two or more devices

texts:
I know it will sound a little bit newbie, but I'm indeed a beginner...
I need to design/define a CAN communication between two devices (one uses a AT90CAN32 from Atmel and the other is not yet defined), without using any specific protocol (CANopen, J1939), but just a kind of a simple "self-made" protocol.
First I just need to do this from a conceptual point of view.

My question is what kind of things should I take into account?

I've already defined a couple of CAN IDs (ex. 0x1FFC) and what kind of data will be sent within these messages. But what should I do next? Do I need to define the whole ACK, CRC checking, etc. "stuff" or is it made by the CAN controllers on the devices?

Sorry if I didn't make myself enough clear, but I don't know how to explain this in a better way...

Thanks in advance for your help!


texts: Dimmer for electric underfloor heating element

texts:
I'm new here and a mechanical engineer who knows just a little about electronics, so please excuse any ignorance.
We have electric underfloor heating in our kitchen. It seems the thermostatic probe under the floor has developed a fault. I can't change it as the stone floor cost many '000s to lay!
The heating element appears fine and has a resistance of 40ohms. I figure on a 240v circuit this draws 6A, 1440W.
I am able to connect the element directly to the supply and it works fine, however as the thermo probe is faulty it is either on or off via a wall switch.
What I would ideally like to do is replace the wall switch with a dimmer switch similar to a lighting dimmer. These at a retail level appear to be 240v/400W/1.6A.
How can I create a dimmer which will work with 6A? Or is there an industrial version I could use?
Thank in advance.


texts:
I need help in selecting the right TVS diode.  I am working on a home security system with a D-Link DCS-5222 camera.

I have built an IR LED array to provide night illumination.  The IR LED array is powered by 12VDC and uses about 1000mA.  I want to use a relay to power the IR LED array only when motion is detected.  The camera had DI/DO pins.  The user manual has some instructions about usin the DO pins with external relay.  See below.

I am seeking help in selecting the right diode and relay.  Any help will be greatly appreciated.


texts:
[Edited to give more details]

I'm trying to build an 6th order Butterworth active op-amp low pass filter with programmable cutoff frequencies of 1/5/10/50/100/250/500/1000/2000Hz.

Another limitation is that it must fit in a very small footprint, about 10mm^2.

I've come up with a design using a three circuit op-amp with a six resistor digital pot with a max resistance of 100kOhms. However, it's only 256 taps.

With those specs, I can only get a f_cutoff of about 2.5Hz to a little over 500Hz.

Can I use a multiplying DAC instead of the digital pot?

I'm going to baseline the noise versus a switched capacitor filter to see which is better. I've been told it's preferable to not use the latter.


texts: Why the led is blinking instead of keeping on atmega8

texts:
I wrote a very simple sample code into my atmega8 via avrstudio here it is:

#include <avr/io.h>

#ifndef F_CPU
#define F_CPU 1000000UL
#endif

int main(void)
{
    DDRC = 0xff;
    while (1)
    {
        PORTC = 0xff;
    }
    return (0);
}

I am expecting all the Pins of PORTC give a high(aka 5v) voltage to make the LED kept on(all the time), but the result is all the Pins of PORTC are given a 160Hz square wave with the high voltage about 25%.

For the record the fuse bit was set as:[ Low: E1 High: 99 ] and no crystal.

So what will be the problem?

EDIT

The output of avrdude with which I upload the HEX to the chip:

avrdude.exe: set SCK frequency to 32000 Hz
avrdude.exe: warning: cannot set sck period. please check for usbasp firmware update.
avrdude.exe: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.01s

avrdude.exe: Device signature = 0x1e9307
avrdude.exe: NOTE: "flash" memory has been specified, an erase cycle will be performed
             To disable this feature, specify the -D option.
avrdude.exe: erasing chip
avrdude.exe: set SCK frequency to 32000 Hz
avrdude.exe: warning: cannot set sck period. please check for usbasp firmware update.
avrdude.exe: reading input file "C:\Users\ximing\Documents\Atmel Studio\6.2\GccBoardProject1\GccBoardProject1\Debug\GccBoardProject1.hex"
avrdude.exe: writing flash (68 bytes):

Writing | ################################################## | 100% 0.10s

avrdude.exe: 68 bytes of flash written
avrdude.exe: verifying flash memory against C:\Users\ximing\Documents\Atmel Studio\6.2\GccBoardProject1\GccBoardProject1\Debug\GccBoardProject1.hex:
avrdude.exe: load data flash data from input file C:\Users\ximing\Documents\Atmel Studio\6.2\GccBoardProject1\GccBoardProject1\Debug\GccBoardProject1.hex:
avrdude.exe: input file C:\Users\ximing\Documents\Atmel Studio\6.2\GccBoardProject1\GccBoardProject1\Debug\GccBoardProject1.hex contains 68 bytes
avrdude.exe: reading on-chip flash data:

Reading | ################################################## | 100% 0.07s

avrdude.exe: verifying ...
avrdude.exe: 68 bytes of flash verified

avrdude.exe: safemode: Fuses OK (H:FF, E:99, L:E1)

avrdude.exe done.  Thank you.


texts: What the name of this coin cell battery and its holder?

texts:
I searched a lot on the internet for any small holder. The smallest I could find was holder for CR1220.

Does such battery and holder sizes even exist?


texts: How do I deal with square, cubic, etc. zeros and poles when manually drawing a Bode Plot?

texts:
I'm manually drawing a straight-line Bode magnitude plot. Say, I have the following transfer function in standard form for a Bode plot:

$$
T(j\omega) = \frac{1+j\omega/10}{(1+j\omega/50)^2}
$$

Should I treat the pole at \$\omega_C = 50\$ rad/s as I would treat the zero at \$\omega_C = 10\$ (except that it would have opposite slope change), or is there something special I have to do with repeated corner frequencies?

References

The Analysis and Design of Linear Circuits, Thomas
http://en.wikipedia.org/wiki/Bode_plot


texts: Read 8 serial ports at the same time with an Attiny

texts:
I'm building a MIDI merger, based on a Attiny (either 84 or 85).

How to read multiple serial ports at the same time (for example 8 RX inputs)?

I can't find the blog article anymore, but I think I did read that it's not as easy as instancing multiple SoftwareSerial objects like this:

#include <SoftwareSerial.h>

SoftwareSerial Serial1(3, 4);
SoftwareSerial Serial2(5, 6);

void setup()
{
  Serial1.begin(31250);
  Serial2.begin(31250);
}

void loop()
{
  if (Serial1.available() > 0)
  {
     a = Serial1.read();
  }
  if (Serial2.available() > 0)
  {
     b = Serial2.read();
  }
}

What is the recommended way to do this?


texts: 200 mA output from the Arduino digital output

texts:
200mA and 0.2V are needed to turn on a mid-IR LED.
Given that the output current of each digital pin in Arduino UNO is 40mA, is sufficient current provided by simultaneously connecting 5 pins to the LED?
Due to the current limiting by the microcontroller, is a resistor also needed to control the input voltage to the LED?

LED Datasheet


texts: Why INA293 provide discontinuous reading on low duty PWM signals?

texts:
INA293 has 110V common-mode voltage
1MHz gain bandwidth
my signal 90V, 100Hz PWM, 10%-25% duty,
load current 30mA max
shunt resistor 5 Ohm
the gain of ic 20V/V

Vout = 30mA x 20V/V x 5 Ohm = 3V
i use esp32 adc to meaure Vout (Vout propotional to current)
at 100% duty only I get a continuous current reading
at 10% duty, or less than 80% duty current measurement is not continuous, it gives zeros in between.. why is that happening?
my load is not inductive as well, same time load is on only for like 0.5sec,1 sec or 2 sec
I cannot use a low pass filter due to PWM pulses are required for my load


texts: Audio power meter with PAM8403 and LM3915

texts:
I have a PAM8403 3W dual channel audio amplifier board bought from Amazon and I would like to connect one of it's output signals to LM3915 dot/bar display driver.
The problem is that PAM8403 outputs differential signals and I can't use that as an input to LM3915.

simulate this circuit – Schematic created using CircuitLab

I tried to couple R+ signal to the led driver using a 100uF electrolytic capacitor but that didn't work for some reason. How do I source the signal to the LM3915?


texts: I was inspecting a PCB with a magnifying glass and noticed some of the light brown ceramic smd capacitors have 3 digit markings on them. Is there a "standard" of what these markings stand for? The first digit looks like a K with a line above it (K̄), and the other two digits are always a letter followed by a number. Example: K̄J4 or K̄A5


texts: Implementing logic functions using universal gates

texts:
As NAND and NOR gates are universal gates, there are often questions like:

  Make the output \$f = (a + b')(cd + e)\$ using NAND gates.

The problem I face is that I take a long time to first convert these logic functions into AND and OR gates and then to NAND. Either the concept isn't clear or I'm just mugging it up. What are some tricks to doing these problems more quickly?


texts:
I am building a project that will lock several cabinet doors using ULN2003AGP chips and security electro magnets similar to this:

AGPtek® 60kg 130LBs Holding Force Electric Magnetic Lock

This magnet has a max current draw of 150ma, which is well below the 500ma that each ULN2003 channel limit.  My plan was to attach six magnets to a single chip, which should draw a max of 900ma, which is also well below the max current limit for the entire chip. (note, my power supply is a box-plug 12v 3A supply.)  My design is shown below. (showing 1 of the 6 connected magnets)

These magnets will typically stay on for hours, then turn of for some amount time between 1 and 30 minutes.  All of them will spend at least an hour on, all at the same time.

My original plan was to power 9 magnets using 2 ULN2003 chips.  However, after connecting one magnet to one chip and two magnets to another chip, I returned a week later to find that the current flowing through each circuit had fallen significantly (the magnets no longer functioned.)  Initial investigation (without a multi-meter) showed that the transistor array was not functioning correctly (though in hindsight, I did not rule out the optocoupler.) Do I need to remove the 100nf caps, add diodes, or modify the way the optocoupler is connected?  Is there another, better way to connect electromagnets to a ULN2003 chip?

simulate this circuit – Schematic created using CircuitLab


texts: Difference between Switch-Disconnector and Disconnecting Switch?

texts:
I'm an electrical engineering student doing an intership at the moment and I was hoping that some of you might be able to help me out with some things I'm having trouble with:

Is a switch- disconnector just another name for a disconnect switch?

Are these circuit elements operated manually (by hand)?

If regular switching is required in the circuit, will it be necessary to also incorporate contactors in series?


texts:
I am using xtr117 current loop transmitter in my current project. I am planning to generate the current loop from xtr117 followed by a DAC 0 to 5v output But the grounds of the loop supply and IRET pin must be isolated.
Is there any method to isolate using minimum no of components. I am attaching my the circuit also

loop supply is provided in series to the loop.
need to isolate the IRET and cl_o1 and also dac's gnd pin (Dac's gnd and loop supply gnd can be connect as chassis ground)


texts: How to improve atmega328p board for solenoids control

texts:
I'm designing a board based on atmega328p microcontroller in order to control some solenoids valves (2 proportional solenoids and 9 ON/OFF solenoids valves).

This is the valve datasheet.
These are the solenoid details:

V = 12Vcc, R = 3.7 Ohm, I = 1.80A

This is my first PCB schematics and my first board.
I power the board with 12V, 40Ah.
I use Eagle and I never did something like this before so the board has many errors. In fact, I tested my first prototype and these are the problems:

When I try to control proportional solenoids (VSX, VDX outputs), the board crashes randomly after few seconds and get stuck. I need to power off and on the board to make it works again.
The datasheet says that the valve should draw 1.8A when powered at 12VDC, but I measured 3A when PWM is 100%. This is very strange!

In order to solve the problem, using the community suggestions, I added these modifications:

Added a big 2200uF 35V capacitor at the main power connector
Added a filter cap between VCC (7) and GND ( 8 ) and AREF (21) and GND (22) and AVCC (20) and GND (22) on the atmega328p
I cut the trace on pin 22 and I directly connected it to the L7805CV GND
Added a diode across each valves pins.

By doing this, the board can work well for 1 or 2 minutes, but then it crashes again.

Now, I'm going to design again my board, so I would like to ask you how I can fix my errors and improve my design in order to make my board works correctly.

IMPORTANT: After few experiments, I notices that if I put in series, between the mosfet output and the valve, a 20R 10W resistor, the board works OK.
The problem is that the resistor becomes hot in no time.
The board works fine also if I put a voltmeter in series between the mosfet output and the solenoid to measure the current: in this case, the board works fine for several time. This is very strange for me!!

I was thinking to:

use optoisolator (like ILD213T) to control the MOSFETs
use an isolate 5V regulator (like NME0505SC or AM1S-0505SZ) in order to isolate the atmega328p from the board
adding filter caps on main power and on atmega328p

What do you think about this?

Can you give me some suggestions, please?

How can I limit the current to 1.8A when the PWM is at 100%?

I know that the board design is not correct, how can I improve it?

Should I use the second layer for GND traces and the upper layer for power traces only?

Please, help me!

EDIT:

I was thinking to use LM25011 with this schematics.
I did this schematics by using the online TI calculator.

Can you tell me if this design could work for my board? I set the Rsense to limit current up to 1.8A at 12VDC.


texts: Sub microsecond jitter accuracy - what to use?

texts:
I have four TTL level signals that must change state in a particular order.

From the “go” signal on one of the lines, all toggling of the other lines will be done within 100 us. The other three signals will toggle at most a couple of times. The start, end and duration between state change that these other three signals will toggle varies depending upon metrics in the system that are know well before the go signal occurs. But the timing is variable so the sequence of pulses and their durations need to be programmable. The timing and duration is known before the sequence starts.

Here’s the rub, I need sub microsecond jitter accuracy. The 120 MHz ARM micro I’m using can’t guarantee such deterministic timing profiles due to pipelining and a host of other performance enhancing reasons. We can do our best to architect the system to minimize the jitter but I want to know if it’s use a faster micro or DSPs or CPLD, PALs, etc. are a typical way to get the accuracy and resolution I’m looking for.

In the past with an 8 bit micro running at 8 MHz with one instruction per clock cycle I could write some assembler, put the micro to sleep, wake on interrupt, count some clock cycles and have 0.25 us accuracy

What technology to I need to investigate to achieve this resolution and accuracy?


texts: Do I need special charger for a Lithium-Ion battery?

texts: I want to use a Lithium Ion Battery. I saw that there is also a different kind of chargers like Adafruit Micro Lipo/MicroUSB or Adafruit Micro USB Lipo for this kind of battery, do I need it? Can I charge my battery direct from a voltage source?


texts: Intuitive way of "visualizing" how the energy is stored in an inductor?

texts:
I've been trying to more or less understand intuitively how energy is stored in an inductor, but I don't seem to get anywhere decent.
In a capacitor I understand, I believe: an external battery pushes electrons and holes (going with the electron/hole theory, even though it's only electrons) to opposite sides and they remain on the 2 plates of the capacitor, forced to be there by the battery. Where we disconnect the battery and let the capacitor discharge through a resistor, there is already a difference in potential in the 2 terminals of the capacitor, created by many +s in one side and many -s in the other side. So as soon as there is a path for the current to go, it will go at full speed and start decreasing, since the difference in potential is also decreasing as the current goes (the number of +s in one side is starting to equal the number of -s in the other side), until Nature goes back to the equilibrium state of same potential in both terminals and we are in current of 0 A.
I'd imagine it as something like this:

But how can I "visualize" this in an inductor? Maybe I don't have the necessary concepts clean enough in my head, so I can't see it clearly as maybe I'm supposed to?
Any help is appreciated!
EDIT: Just to say, the idea here is to understand intuitively, so I don't need to memorize the formulas to know what's gonna happen in some part of a circuit.


texts: Physical connection of AC and DC voltage sources in series

texts:
in many circuits (Amplifiers, Filters etc) at the input terminal I saw a sinusoidal voltage together with a DC term, i.e. a voltage like v(t) = sin(wt) + 1 [V]. We may imagine that this signal is produced by the series between an AC voltage source and a DC voltage source, as shown in the following picture:

Now my questions are:

1) I saw the previous scheme in a lot of theoretical analysis of circuits. But is it physically possible to connect an AC voltage source and a DC voltage source in that way? Or is there the risk of damaging them?

2) If this connection is allowed, is it ok for any frequency? May for instance an AC radiofrequency voltage source create a disturb on a DC voltage source?


texts: simple clamp circuit resistor calculation

texts:
Hello guys i want to calculate the resistor R in this circuit.Can anybody help me?

The value of zener diode(VZ)=4.8 volt.

well i try to simplify  it

My question is is my solution is right??If not then what will be the value of R?


texts: esp32 driving zener diode with 2.9v threshold at the gpio

texts:
If I want to drive the Zener diode with the ESP32 GPIO, will that be appropriate? What factors to look in this case?
I want this as a low voltage detector?


texts: Why am I seeing a low voltage when the switch is open?

texts: I'm building a battery test circuit to check the voltage of the source battery and I've added a Sziklai pair of transistors in as I need to be able to shut off the voltage so that I don't have a low current constantly being drawn while the MCU is asleep.  I've put in a multimeter to simulate what I'd be getting as an input into an ADC.  When the switch is closed I get 4.815V which is what I expect, when the switch is open however, I am getting a reading of 0.108V and I can't for the life of me work out why there is any voltage present.


texts: 16x2 LCD display not working with arduino or RaspPi

texts:
I have a 16x2 LCD display that I'm just trying to use for the first time. The model number is 1602D1 according to this datasheet from where I purchased it. I first tried attaching it to a Raspberry Pi using Adafruit's tutorial, which had the same pinouts as the LCD display I have. Now I've tried using an Arduino and I get the same results, which are shown in the picture below.

The LCD display never updates when I try to send text to it and only displays the blocks in the bottom row. Adjusting the 10k variable resistor doesn't seem to do anything. When I send data to the LCD, I notice it flickering slightly as if its updating, but no text is displayed.  I'm simply using the code from tutorials, nothing special.  Any ideas what I am doing wrong? Thanks.

For clarity because the picture might be misleading, here is how I have the pins hooked up:

LCD Pins:

LCD 1 - Ground
LCD 2 - 5V
LCD 3 - 10k Variable resistor middle pin
LCD 4 - Arduino 12
LCD 5 - Ground
LCD 6 - Arduino 11
LCD 7 through 10 empty
LCD 11 - Arduino 5
LCD 12 - Arduino 4
LCD 13 - Arduino 3
LCD 14 - Arduino 2
LCD 15 - 5V
LCD 16 - Ground

Variable resistor:

Left - 5V
Middle pin - LCD pin 3
Right - Ground


texts:
I want to use a rotary DIP switch to set an ID number on a number of identical boards I am using for a project. I have run into the following three lines in the data sheet and I can't make sense of them:

Contact Rating:

  Non-Switching: DC 50V 100mA
  switching: DC 5V 100mA
  Minimum: DC 20mV 1uA

What do these lines exactly mean? What is the meaning of Switching as opposed to non-switching?


texts:
Amplifier ICs always list the maximum load the amplifier is stable with. For example, a class AB amplifier is listed as 8 ohm capable.

Is that amplifier suitable to drive a 32 ohm load?

Are there any attributes that make an amplifier better suited to drive a lighter load vs a heavier load?

If a similar amplifier is 4 ohm capable, is it less suited to drive a 32 ohm load?


texts: Can an alternator cause components to run at a higher-than-rated voltage?

texts:
Given that the voltage regulator on my motorbike is set to 14.3 volts (so that it charges the 12 volt battery effectively) and given that the alternator is what provides power for the electrical system while the battery is charging, does this mean that the components in the system rated at 12 volts are being run above spec (ie. at 14.3v)?

Is this safe or could it shorten the life of the components (which are mainly regular incandescent bulbs and LED bulbs)?

Part of me thinks that the designers are relying on the voltage drop caused by the long runs of cable in the wiring loom to effectively reduce the voltage to near 12v by the time it reaches any components.


texts: Can a isolation transformer be beneficial when coupled with a lab linear power supply?

texts: Linear power supplies are already low noise, so adding an isolation transformer is pretty redundant but I'm curious, will it make a measurable difference or will the benefit drown out in the already present noise?


texts:
I read that hard disk read heads use "giant magnetoresistance" so I assumed that I could measure a resistance change in the presence of a magnet.  Unfortunately I failed.

The read head came from a 3 headed Fujitsu laptop HDD.  It had 4 connections so I assumed two were read and two were write.  Once wired I measured about 5 ohms and 1/2 micro henry on both pairs and got no change placing or wiggling a magnet in front of it.  Connections were very difficult to make (microscope and air heater), but I am reasonably sure they were good. There was no connection between pairs.

Should I be able to measure a resistance change this way?


texts: Why is the set of white labels on a PCB called the "silkscreen"?


texts: Connecting 21" screen to LVDS connector on motherboard

texts:
I'm working in an "All-in-One pc" project. For that, I have an old Dell laptop (which only works with DC adapter) and a 21" LG monitor.
My question is: How can I connect the LCD panel directly on the motherboard? I'm looking for a cable pinout that I could use.
With that I hope I could:

-Save the HDMI port of the motherboard for a second monitor when necessary.

-Eliminate circuit boards and save space

-Have only one ON/OFF button

-Have only one DC adapter.

This is the Dell motherboard DNE40-CR datasheet

And the LCD panel LM230WF3 datasheet

I need some help reading those pinouts, but I already know the motherboard has more connections than I need, so we could ignore webcam and microphone.
I noticed some differences, the LCD requires 5V and the motherboard supply only 3,3V. Maybe a jumper though USB +5V could fix it?


texts: Wires not snapping to pins on component in Altium 19

texts:
I updated my PCB document based on my schematics and noticed a few nets were missing between components. For example, my current limiting resistor doesn't have a visible net to my LED.
I went back to my schematic and they look visually connected. When I clicked and dragged my LED with my mouse away from its position, I noticed the wires were snapped to the pins (they weren't moving with the LED,) which seems to me like they're not 'connected.'
However, no matter why I do they are not snapping. I have other components where one pin has successfully connected to a wire, but the second pin has not, and the net isn't showing.
Is there something I'm not doing properly? Is it to do with when I created the schematic symbol?
I appreciate any help, first time making a PCB in Altium and couldn't find any clear answer online.


texts: Can every L1 GPS/GLONASS/BeiDou GNSS antenna receive E1 Galileo too?

texts:
I want to buy a survey grade single frequency L1 GPS/GLONASS/BeiDou/Galileo GNSS antenna (survey antennas have a ground plane built in). I found a product that specifies it is a GPS/GLONASS/BeiDou multi-frequency (L1, L2 etc.) antenna but it does not list Galileo. The Galileo E1 signal (called L1 earlier, I hope it is the first/main signal) has the same center frequency as GPS L1 (1575 MHz). Will the antenna be able to receive Galileo E1?

The L1 vs E1 signal bandwidth for GPS vs Galileo may differ a little bit but I am not sure if that can be an issue.

Here are some references:

GPS Signal Plan
GLONASS Signal Plan
BeiDou Signal Plan
Galileo Signal Plan


texts: Effect of right half plane zero on bandwidth of control system

texts: It is known that the right half zero and  the delay limit the achievable bandwidth of a control system. Can someone please explain the reason, how the right half plane zero limits the achievable bandwidth and how the time delay in a control system limits the achievable bandwidth of a control system?


texts: How to replace AVR _delay_ms() with timer

texts:
Good day.
I need problem with replacing _delay_ms() bultin function with timer.
MCU: Atmega644@16Mhz
My code (simplified):
volatile uint32_t u32_timer1 = 0;

void InitTimer1()
{
    uint16_t u16_timer_ctc = 15999;

    /* CTC mode, clock divided by 1. */

    TCCR1B |= (1 << WGM12) | (1 << CS10);

    /* Load the high byte, then the low byte into the output compare register. */

    OCR1AH = HIBYTE(u16_timer_ctc);

    OCR1AL = LOBYTE(u16_timer_ctc);

    /* Start the timer 1 in CTC mode. */

    TIMSK1 |= (1 << OCIE1A);
}

ISR (TIMER1_COMPA_vect)
{
    /* Event to be executed every one millisecond. */

    u32_timer1++;
}

void DelayInMilliseconds(uint32_t NeeededDelay)
{
     //Currently call _delay_ms() function, but I want replace with timer1.

    _delay_ms(NeededDelay);
}

int main()
{
         InitTimer1();

         while(1)
         {
                 SomeCodePlaceholder();
                 DelayInMilliseconds(300);
                 SomeCodePlaceholder();
                 DelayInMilliseconds(50);
                 //ETC....
          }
}

I need replace code in function DelayInMilliseconds()using timer 1, not _delay_us().
EDIT: My approach using timer 1:
uint32_t u32_milliseconds_present = 0;

uint32_t u32_milliseconds_past = 0;

void DelayInMilliseconds(uint32_t u32_delay)
{
    u32_milliseconds_present = u32_timer1;

    //NOW WE HAVE MS ELAPSED, BUT WHATS NEXT?
}


texts:
I am new to PIC programming and I am doing an exercise with UART. After building the program the message is not being displayed. Can someone tell me where I am wrong. BAUDRATE = 9600, _XTAL_FREQ = 20Mhz. My code:

void initUART(void)
{
 TRISC6 = 1;        // TX
 TRISC7 = 1;        // RX

 SPBRG = ((_XTAL_FREQ/16)/BAUDRATE) - 1;
 BRGH = 1;      // high baud rate
 SYNC = 0;      // async
 SPEN = 1;      // configure RC6 RC7
 CREN = 1;      // continuous recep.
 SREN = 0;
 TXIE = 0;
 RCIE = 1;
 TX9 = 0;       // 8-bit txn
 RX9 = 0;       // 8-bit rxn
 TXEN = 0;      // reset tx
 TXEN = 1;      // enable txn
}

void main()
{
 initUART();
 GIE = 1;
 PEIE = 1;

 senddata("Embedded systems");
 while(1){
    //sendbyte(receivebyte());      //when interrupts are disabled
    }
}

void senddata(const unsigned char *data)
{
 while(*data)
    sendbyte(*data++);
}

void sendbyte(unsigned char byte)
{
 while(!TXIF)
    TXREG = byte;
}

/*char receivebyte(void)
{
 if(OERR){
    CREN = 0;
    CREN = 1;
    }
 while(!RCIF);
 return RCREG;
}*/

void interrupt isr(void)
{
 if(RCIF){
    if(OERR){
        CREN = 0;
        CREN = 1;
    }
    sendbyte(RCREG);
    }
}


texts: Finding/Calculating LED light luminosity / power output

texts:
Is there a simple way to determine the light intensity / power output of an LED?

e.g.
Light output = current x F.Voltage - heat dissipation
Light output = efficiency x current x F.Voltage

I can't find heat dissipation, efficiency or similar on any datasheets. Only maximums. A few datasheets give mW/Sr or cd values.


texts: I want to implement a math equation in FPGA, should I describe a CPU or can I do it just by code?

texts:
For a school project I'm trying to implement an equation for example like this:
(EDIT)

B = ((A + 2) * |A - 10|) / (c * c)

everything is unsigned binary values, absolute values always.
The equation should be evaluated 57600 times per second for an image of 240x240 pixels.

I don't know how to start it. Would I be better to implement it by making a MIPS processor and load a list of instructions of the program in assembly and so?

Or should I do a direct approach by code? If so, what methodology should I follow, should I do FSM? Should I use clocks?

I tried to program it by easy combinational (assign... etc) and it works, but it uses almost 80% of available ALMs. I don't think this is the best way, I'm looking to make it the less hardware usage possible, time is not a constraint. I'm using Quartus II and Verilog.


texts: Another Baudrate Issue, when switching from 9600baud to 300baud

texts:
I am communicating with an 8051 MCU via a CPU. When I i/p a character on the Keyboard, I expect the MCU to transmit a character string back to the CPU, which I can view from the terminal window., one for 9600 Baud, 8N1 and the other for 300 baud,7E1. At initialization, I am communicating at 9600. At a the input of another command character, I intend to switch the baud rate to 300 baud. And this works, as it MCU send a confirmation string to the 300baud terminal. But after the switching it appears that the MCU does not receive any longer, as though the Serial ISR no longer functions. I used a serial port monitor to see what happens, and I discovered that I am actually sending after the switching, but the MCU does not recognize it, appearing to be in a while(1) loop. Find below the C code:

Main:

main()
{
    SET=1;
    IE=0x90;    //Enabling serial interrupt.
    initUART_baud(SET);     //9600 Baud.
    while(1)
    {
        if(debug  && !ch_baud)
        {
            debug=0;
            UART_SND(intro);
        } else if(debug1 && !ch_baud) {
            debug1=0;
            UART_SND(intro1);
        } else if(ch_baud) {
            initUART_baud(SET=~SET);    //change baud rate.
            ch_baud=0;
            UART_SND(NEWbaud);
        } else
            continue;
    }
}

void initUART_baud(unsigned char change)
{ //initializing UART to initial 300baud.

    SCON = 0x50;            //UART in MODE 1, RECIEVED enabled.
    TMOD = 0x20;            //auto-reload mode and Timer 1 selected
    if(!change)//if Zero
    {
        TH1=TL1=0xA0;
        ST_7E1=0;
    }   //300 BAUD
    else
    {
        TH1=TL1=-3;
        ST_7E1=1;
    }   //9600 BAUD
    TR1 = 1;                //ACTIVATE TIMER T1
}

void UART_SND(unsigned char *SND_BUFF)
{//SENDING STRING

    unsigned char value;
    while(*SND_BUFF)
    {
        if(!ST_7E1)
            value = Parity_7E1(*SND_BUFF);  //CHANGE DATA FORMAT (7E1)
        else
            value=*SND_BUFF;
        SBUF=value;
        while(!TI);
        TI=0;
        SND_BUFF++;
    }
    SBUF = 0x0D;    //'CF'
    while(!TI);
    TI=0;
}

void serial_Optical_isr(void) interrupt 4
{
    RI = 0;
    IR_BUFF = SBUF;     //putting the value in UART into temporary buffer
    switch (IRvalue)
    {
        case START:
            if(IR_BUFF==0x54)   // If "T" is send
            {//HHU sending Request
                IRvalue=DIS;
            }
            break;

        case DIS:
            if(IR_BUFF==0x44)   //D
            {
                debug=1;
                IRvalue=START;
            }
            else if (IR_BUFF==0x42)    //B
            {
                debug1=1;
                IRvalue=START;
            }
            else if (IR_BUFF==0x43)    //C
            {
                ch_baud=1;
                IRvalue=START;
            }
            else
                IRvalue=START;
            break;
    }
}

This code ought to transmit the character in buffer "intro", when TD is pressed, and the character in buffer "intro1", when TB is pressed. And when TC is pressed, the baud rate changes and transmit character in buffer "NEWbaud" to the 300baud terminal. And the TD & TC send intro and intro1 string respectively when pressed at the same 300 baud.

I will appriciate any form of assistanc. If there is a bug in the code, do point my attention to it. Thanks a buncH!


texts: Voltage on circuit input different than on power supply

texts:
I'm using a really good 5V-35A switching power supply to power some mini PCs (Cubieboards if that matters) as below.

simulate this circuit – Schematic created using CircuitLab

The weird thing is that when I measure the voltage on the PCs input terminals, they are below the power supply's voltage. If I measure it directly at the PS it's always 5.2V, no matter how many PCs I use on the circuit. However, If I measure it on the terminal that connects all the PCs, it gets lower and lower as I increase the number of PCs.
Even though they are connected in parallel!!!

They don't have any other connection between them, only the power source.

The terrible thing about this is that after about 5 PCs the voltage gets so low that I can't power any PCs anymore (and I need to power around 20 of them using this source). I've tried using a different power supply and different connectors and the results were exactly the same.

What could possibly be happening? How can I solve it and what should be the best way to power all of those devices using the supply I have?

Thank you in advance,

Theo


texts:
I have a power amp that is essentially functions like a benchtop supply, and you can connect banana plugs into it. I would like to protect it against ESD, but also protect the amplifier. People in our manufacturing floor are stupid and sometimes connect things like batteries to the supply up backwards, I really can't prevent that, and if they do they will blow the diode right out. Is there a good way to protect the diode also? These are the ways I could protect it that I don't necessarily like:

I could fuse it but there would be no way to know if the fuse was blown and then you still have no diode and no protection and nobody on our floor would replace it.
Resistor in series, I don't like this idea because it makes the diode less able to sink ESD and protect the input. 8kv (human body model) across a 1ohm resistor is 8000V
Placing a resistor anywhere from the amp to the terminal will be bad, too much current.

simulate this circuit – Schematic created using CircuitLab


texts:
I have never protected my USB interfaces for microcontrollers until a USB port of my PC stopped working because of a bad connection aparently. So I'm starting to protect them but I found some ESD IC's that protect them but my question is...

Is there a simple way to do it with discrete components?

I came across with some schematics using a pair of resistors and a pair of zener diodes.

Is that enought to protect them?

Extra info on usb protection: http://www.digikey.com/techxchange/message/6040


texts: Calculate voltage and current in time dependent circuit

texts:
I'm working with this time dependent circuit, and i'm having troubles with some of the assignments.
The following values are given R1 = 1kΩ, R2 = 2kΩ, R3 = 1kΩ, C1 = 22uF and C2 = 47uF. Is delivers 20mA, and when t=0 the switch goes from connected to disconnected. The circuit is stationary for t < 0 (when sure what that means?)

First of i shall calculate the current through R2, when T<0. Is it right when i assume i should use current division? Calculate the total Ω of the circuit, and divide by R2, times the 20mA?
Next, i shall calculate the voltage across C1. That one i'm uncertain about. I have found a formula V = q/C, but i can't seem to find q, the charge, or neither how to calculate what?
Lastly i shall find an expression for the current i(t) for t>0. Here i'm a little lost, so hoping for some guidance

Might be rather easy, but for a newbie, who have been introduced to all at once, its hard to find head and tail,

Hoping for help!


texts: How to use braking in this DC motor control system?

texts: I am running a DC motor through a DC controller(DC60DP500-800BL-R01 Keya PWM Electric Vehicle Controller) in a lifter. It's working fine but the only problem is even after stopping the motor the lifter still keeps on moving because of its momentum. I want to make it stop instantly by applying some kind of motor braking. So how can I achieve this? Any suggestion/hint will be greatly appreciated. The circuit is attached. Please have a look and suggest accordingly. Thanks


texts: Reverse polarity protection using MOSFET - what is the voltage drop after it?

texts:
I am using this schematic for reverse polarity protection of an IC (bq78412). However the same IC has an ADC that senses the source voltage and appears not to be tolerant to reverse voltage either. Since the IC is measuring the voltage with +-0.5% at 12V I assume that it would not harm if I measure the voltage after the MOSFET since according to the data sheet its Rds(on) is about 0,082 Ohm at Id = - 3A. The total current consumption of the IC is 3,2 mA. So I assume a voltage drop of 0,082*0,0032= 0,2624 mV which is way below 0,5%*12V = 60 mV.

Is this assumption correct?

Vinput = 12v +-3v
Q1 - SI2319DS

Thanks!


texts:
I refer to the two round yellow-ochre things mounted on the blue capacitors. They are coupled in series from a sold-state power amplifier stage, and the capacitors AC couple to the speaker load. The mystery components appear to be inductors but they aren't featured in the schematic. They measure 1R3 and about 140mH.

And if it is an inductance, what would be its purpose? At 140mH it seems far too large in an audio circuit.


texts: RLC filters. How to determine band pass filter?

texts: I have done question on frequency response of RLC it is easy to find whether a given circuit is high pass filter or low pass filter. But I am wondering how to determine for band pass or band reject filters. Please help me and I would be obliged if someone explain it by considering an example of a passive filter (containing all R,L,C).


texts: Negative sign in general transistor current equation

texts:
The transistor current equation is

Ie = -(Ic+Ib)

Why is the negative sign sometimes used?


texts: Making 2 layer board, using ground pour when I already use ground plane?

texts:
I'm working on a project were we are making PCB for measuring weight with 24-bit ADC (AD7792), MCU and GSM module.

Because those measurements are highly sensitive, we are considering AGND and DGND separation.

I know that for this project most of you would recommend 4 layer board, but due to some circumstances (long story) we can make it only now in 2 layers.

So my questions are:

When we use ground plane on bottom layer, are there any benefits of using ground pour on top layer where signals our routed? In case of AGND and DGND planes on bottom side, is it good to even have a ground pour on top side because of coupling noise with AGND on bottom?
I saw on OpenScale board (https://www.sparkfun.com/products/13261) -> under the documents, eagle files, that they route signals under both side. Is it a good practice to route few cm long traces on ground plane?
Also on that board I saw that they are connecting top ground pour to every ground pad. Is it good idea? I thought that ground pour is only here to curve electric filed (reduce crosstalk) and that no return current should flow through it. And that return current should flow on ground plane underneath signal trace to cancel magnetic filed of above signal.
How should ground pour be connected to power supply gnd? Is it grounded to bottom ground plane with vias? In that case how to avoid "strange" currents paths when we are doing ground plane separation?

Thank you!

P.S. Sorry if my question are confusing and in some term repeating, I'm so confused with all this in that case that I can't even write concise question :)


texts: How can you calculate base voltage of a transistor when there are biasing resistor and a resistor between 2 input terminal

texts:
I just get to know about transistor a little. Here is my question

As you can see that here the transistor is configured to be an amplifier in common emitter mode. R1 here is the bias resistor. What I don't know is how Vb can be calculated. Suppose the input voltage is known already but here the input voltage is affected by R1 and R2 that make Vb is different from input voltage. Also, R1 is connected between b and Vcc that also affect Vb.

I learn how to calculate voltage, current and resistance (or impedance) of parallel and cascade circuit but this case look strange and KCL can't be apply here also (or it's just me who don't know how to apply it). Of course, in real life I can use voltage measure device to know its value but I am talking about math here.


texts:
In my project I need a level shifter for a 3.6MHz clock.
The problem I have with my design is that in order to respect the requirement I have, my rise and fall time need to be <25.2ns

I used the following design, I tested first with the 2N7002 but it didn't even have the time to reach the 5V. When I simulate this design I have the following results:

Based on the simulation I should have a 18ns rise time and almost instant fall time, but when implemented in practice I get a 40ns rise time. Do you think there is another MOSFET transistor (SOT23 package) that would make me shave off few more nanoseconds or I should totally rebuild my design ?


texts: What are the implications of using PROGMEM?

texts: With large amounts of text variables, I've found it necessary to store them in the Flash memory using PROGMEM.  What are the positive and negative consequences of storing large variables in Flash (using PROGMEM) vs SRAM vs EEPROM on the Arduino?


texts: I've got a SOT-23 transistor (I think, but it could also be an IC) marked with 1E. Another one is marked with A7W. Then I can also see WR5. How are you supposed to decode these?


texts: Timings constrains for isochronous clocks

texts:
In my Verilog design, I have two clocks of the same frequency, but of different phase. At the moment, my timing constraints look like this:

create_clock -name clk1 -period "150 MHz" [get_ports clk1]
create_clock -name clk2 -period "150 MHz" [get_ports clk2]

The problem is that the compiler doesn't complain when signals cross the two time domains, although it should because the two clocks are asynchronous, and metastability protection is required.

The "hack" of changing one of the frequencies to 150.01 Mhz works, but it's a hack. Is there a proper way of setting timing constraints for isochronous clocks?

Edit: I'm using Altera Quartus II as my compiler.


texts: Bi-directional TVS diode - how to know which diode is failed

texts:
I have a TVS device with 2 zener diodes connected in series and sharing the N-substrate.

After doing bench testing on the unit, it seems that the I-V curve is only showing uni-directional junction of a typical diode. I had supplied +Ve supply to the Anode connection (D1) and -Ve supply to Cathode (D2). Unfortunately, now I'm not sure which diode is failing and how it's happened.

Is the I-V curve that I'm seeing only the D1 curve or D2 curve? Can anyone help to explain the mechanism to me?


texts: How this device "Electronic Anti-lost-Anti-theft-Flashlight" measure distance?

texts:
Sorry i don't speak english but ill try.

We want to design a system of a receiver and transmitter in RF, that it "beeps" when it is a certain distance one of each other.

I found this: http://www.amazon.com/Electronic-Anti-lost-Anti-theft-Flashlight-receivers/dp/B00QNE6QWI

It works 433.92M Hz.

So my question is, how this system measure the distance? i want to design something like that.

Sorry for my bad english, ill hope was understandable.


texts: Why isn't the current through the resistor equal to 1A?

texts: Current through the 1 Ohm resistor came out as 1A, however this is apparently incorrect.


texts: How does dimming of driverless LEDs work?

texts: I have read this article which describes different generations of driverless LEDs. Now there are also driverless and at the same time flicker free LEDs on the market (for example here). So what are the state of the art techniques to get flicker free dimming with driverless LEDs? How do the plots of the output current look like in a dimmed state? I know that with drivers one can use PWM or AM dimming, and I know how the plots look like in this case, but how does it work in the driverless case?


texts: Workings of a microwave oven magnetron transformer

texts:
I took apart an old microwave oven just to see what happens with the circuit inside it. The overall idea is actually pretty simple, but I'm having a hard time figuring out some parts of the circuit. Here's a picture of the main circuit viewed from behind the LCD control panel:

At this point, I have figured out that the door switch must be closed for anything to work in the microwave, for safety purposes, obviously.

I have disconnected the magnetron and its transformer from the circuit. I found there are two wires leading to the high-voltage transformer for the magnetron. My main question is, when I'm probing the two wires, (white and red off to the left), I put the GND probe on the common ground (the metal piece to the right), and the positive probe to the wires. But each time I try this, both wires show 120V AC. Does this make sense? I'm thinking that one should be +120V and one should be ground. However, when I probe the two wires (positive probe on red wire, GND probe on white), I get 0V AC. How is the input to AC transformers defined? Both are hot or one hot and one GND? I feel like it should be a full circuit, with positive and ground to the input terminals of the transformer, and a higher positive and ground out from the output terminals.

(All this is done with the power plugged in and I've set the time on the LCD and have started it.)


texts:
Apologies if this question has already been asked or it's too simple.

I am starting out on Microcontrollers and I have been looking at the following:

https://www.sparkfun.com/products/9195

Now, I have skimmed the data sheet and have the following Pin schematic:

Should I therefore connect the power supply (battery powered) to pin 20 & 19?


texts: Why aren't cascaded NOT gates used as frequently as flipflops?

texts:
simulate this circuit – Schematic created using CircuitLab

I am going through Digital Electronics course and came across Flip Flops. As the cascaded NOT gates basically do the same functioning of storing the bits as Flip Flops do(just connect output of second NOT gate to input of first NOT gate), and that too with use of only two gates(for flip flop there are at least two NOR or NAND coupled, plus two AND gates for combining clock), why aren't they used as much as flip flops are used?


texts: Can you discharge a 3s LiPo battery from both its main plug and it’s balance plug?

texts:
So I’m building a quadcopter, and I want to be able to use the same battery to power both the escs and the flight controller.

However, the escs are connected to the PDB which is connected to the main plug of the lipo. I was wondering if it was safe to then use wires 1 and 3 of the balance plug to get 7.4V, and power the flight controller with that?


texts:
I'm a total newbie at this, and I'm trying to make my Arduino-mini work on batteries.

Is it 100% safe if my arduino (or other components) receive like the minimum current to the point it's about to shutdown, but keeps working ? Can this damage anything in the long run ?


texts:
I am currently studying BJTs but am having trouble analysing the four resistor bias circuit. My textbook gives the following circuit and says we can use voltage divider across R1 and R2 to find VB.

But I feel like we can't ignore RE when we try to find VB. Shouldn't RE (and the 0.7V drop across VBE) combine with R2 in parallel and then use the voltage divider with that parallel combination and R1?


texts: variable should not be used in output port connection

texts:
I searched random verilog heirarchy to understand how to properly instantiate modules. I found one on https://www.altera.com/support/support-resources/design-examples/design-software/verilog/ver_hier.html

I am getting an error saying "variable 'intsig' should not be used in output port connection"

module top_ver (q, p, r, out);
input     q, p, r;
output    reg out;
reg     intsig;

bottom1 u1(.a(q), .b(p), .c(intsig));
bottom2 u2(.l(intsig), .m(r), .n(out));

endmodule

edit 1

module top_ver (q, p, r, out, clk);

input     q, p, r ,clk;
output    reg out;
reg     intsig;
    always@(posedge clk) begin
        bottom1 u1(.a(q), .b(p), .c(intsig));
        bottom2 u2(.l(intsig), .m(r), .n(out));
    end
endmodule


texts: Anyone know how to make UI text and objects display larger in EAGLE CAD. I just got a laptop with a 4K display and it looks beautiful but the text in some programs is microscopic


texts: Combining trailer tail lamp and turn signal onto one wire

texts:
I am looking to attach a light to my tow vehicle that will be powered when towing via a 12V wire.

I also will have a 2nd wire that will supply 12V when the turn signal is turned on. At this point, I am not sure this is even possible but what I am looking for is when 12V is supplied to the turn signal, the light will flash in sync with the turn signal. Of course this is now backwards, because 12V would mean ON and 0V would mean OFF. So there needs to be some delay or some way of detecting when the turn signal has received 0V and not received 12V within a certain time period, that it would default back to the light being on.


texts: Why does my Android phone charger cause my (powered-off) stereo receiver to make a high-pitched chirping sound when plugged into the same powerstrip?

texts:
After days of scouring my apartment, wondering if I’d developed another pitch of tinnitus, trying to figure out what the hell was making that infernal noise, I finally isolated it to this.

Onkyo receiver is plugged into a powerstrip
Android phone charger and cable plugged into same powerstrip.
it’s an old powerstrip. I got it at a flea market for a buck. Until this, it’s worked great.

This causes a continuous high-pitched chirping sound, from the receiver—not the speakers. It’s quiet enough to make me wonder if it’s really there, but loud enough to drive you crazy.

Why must these devices torture me so?


texts:
I am looking to build an audio interface that can also use real-time DSP to process audio coming from (most important) and going into the host.

After some research, I have been zeroing in on the xCORE-200 Multichannel Audio Dev Kit but want to make sure it is the right kit for my intended purpose.

here is a link to a commercial product that is in line with what I'm thinking of doing: https://www.uaudio.com/audio-interfaces/arrow.html

The main important thing about this device from Universal Audio is that it allows the user to use real-time effects on the audio coming from the host, thus saving the host from having to do all the work which is ultimately what I would like to do with my own C/python based effects that I've been writing.


texts: Circuit inverts at high frequency and is unity at low frequency

texts:
Does anyone recognize this op amp setup?

I've figured that at low frequencies C1 is as short circuit, putting the +ve and -ve inputs to \$V_{in}\$ and at high frequencies it will be as open circuit putting +ve and -ve to virtual ground, making it an inverting op amp (unity inverting?).

I have to find the transfer function (and subsequently, bode plots), and my attempts so far haven't quite worked.

simulate this circuit – Schematic created using CircuitLab

I was wondering if it had a name I could do some research on to understand how to go about it.


texts:
My vaping device operates in two modes, variable temperature control (VT) and variable wattage (WT). The unit first sends out a ~1 second 30 watt/7.74 volt surge to the coil to see which mode it should use(according to the coil you installed). This spike is actually a design flaw in the firmware, it should happen in a fraction of a second and basically unnoticed, a return or refund is not an option anymore. An updated firmware does not do this.
What this spike does is scorches the coil and the ejuice and then hurts your mouth, throat and lungs.
 My question is: I personally need a maximum of 7.0 watts/3.74 volts so could I not just install a resistor, diode, voltage regulator... (close to 7.0/3.74v range) between the control board and coil connections to prevent or absorb this 30w/7.75v spike?


texts: What is the voltage across the capacitor at t=infiniti in this circuit?

texts: Hi, I just want to verify my answer for a). Is Vc(infinite)=10V since it open circuited at t=infinite? Or do I need to use voltage division to find Vc?


texts: What is the impact of Earth's magnetic field polarity on consumer electronics?

texts:
Earth's magnetic poles are known to have inverted in the past. How are commonly used circuits or component of consumer electronics (from energy production/transportation to TVs, mobile phones and PCs) going to be affected?

Other than compasses, I think.


texts: I had a 2sets of LED series circuits which runs with 12V DC, 1A as shown below . Each set will be of 3 series of four LEDs. My problem is that when i connected to 12VDC,1A source, the set1 brightness is higher than set2. how to overcome this problem ?


texts: Current sense circuit for 0.1uA to 100mA dynamic range

texts:
For a battery powered sensor node, I need to be able to measure current levels that have a dynamic range from 0.1uA [standby current] to 100mA [peak current].

For this, I am thinking of a high-side current shunt resistor and amplifier feeding an ADC. For the shunt, I could go with a 0.1ohm resistor to minimize the voltage drop in the peak current case [but lose capability to measure standby current], or go with a 10ohm resistor to have some shot at being able to measure the standby current of 0.1uA [but risk too high a voltage drop in the peak current case].

This must be a pretty standard problem for people measuring currents at sensor nodes.

For someone who might have resolved a similar issue in the past,

What circuit did you design for measuring currents ranging from 0.1uA to 100mA [being able to measure standby currents of the order of 0.1uA is critical for me]
What type of shunt resistor and amplifier did you select?

[Edit: This question is different from the one here as I am trying to design a single circuit that would measure across 0.1uA to 100mA - without having to manually switch resistors. The main solution in the answer to the other question requires one to set beforehand the current range to be measured. My question addresses a different problem.]


texts: Considerations for long UPS battery life

texts:
I have brought my APC Smart UPS (750VA) to a local UPS merchant and service company to a checkup recently and I asked a new pair of CSB batteries for it. I have used a few types of batteries for this UPS and experienced that CSB batteries were the long lasting ones and its price worth the less frequent recalibration and battery ordering-replacement procedures for me. (I mean here the lifetime of the battery, not the running time in case of AC power loss.)
During the takeover they said that premium batteries (like CSB) are not always the best choice for every UPS (depending on the condition of the UPS), it might perform better with lower quality batteries. After the checkup they will suggest the best one for this specific UPS.
I've asked for details but we didn't get too far. An old regular car might not get the best performance from a new sports car component... - they said.
Could be any reason to use non-premium batteries for the longest battery life or they just have higher margin on cheaper batteries? What should I consider for the longest battery life (with APC Smart UPS-es)?


texts:
I have a zero crossing circuit for dimming lamps exactly like the below

According to my calculations:

\$ I_{R7} = \frac {V}{R} = \frac {3.3}{10k} = 0.33~mA\$.

Considering TCMT1109 transfer ratio equal 200% (worst case), when the input current get lower than \$0.165~mA\$ the ZC signal should start rising.

\$ V = {R}*{I} = {200k}*{0.165~mA} = 33~V\$.

Adding the optocoupler and the bridge voltage drop, let's assume \$35~V\$ the minimum input voltage to detect the zero crossing.

The mains voltage is \$220~Vac, V_{peak}=311,12V\$, and the frequency is \$60~hz\$.

\$ V(t) = V_{peak}*sin(wt) \$

\$ 35 = 311,12*sin(2*pi*60*t) \$

\$ t = 0,299 ~ms \$

After calculations, I was expecting the ZC signal start rising at least at 0.299 ms, but after measure at oscilloscope I got the ZC start rising around 0.450 ms.

I know this is a very low time, and I can manage that at the microcontroller firmware. I'm just worried because I can't get the 0.450ms (50% higher than 0.299ms) at any calculations I make.

Where am I missing at calculations? I considered the lower CTR for worst case.

Where is my analysis wrong?


texts: I am stuck on a very simple project since days and i can not figure out what i am doing wrong. The project is about the darkness sensor i.e "the led should light up automatically in darkness and shutt off in light". But in my case its the opposite, led turns off in darkness and turns on in light. I am using and have tried almost all the circuit diagrams from youtube tutorials which are almost the same but with few different resistor values. Also they seem to be using the transistor bc 547 while i am using the bc 548 transistor. Please help me understand what i am doing wrong here?


texts: Modifying AA powered toy engine to be remotely turned on/off

texts:
I want to make a remote for Thomas Battery Powered Engine that will allow it to be turned on and off, but I don't even know where to start. I assume I'll need a receiver that can toggle power on and off to the motor in the engine and an external transmitter. Can I use the AA battery in the engine to power the receiver?

My hope was to be able to control multiple units via bluetooth from a smartphone.

What should I read/ask/buy to get started?

I'm not even sure this is on topic for this site.


texts:
The "ice cube" relay in question is allen bradley's 700-HC series. I was browsing through the spec sheet looking at the electrical data to make sure that the relay has the proper voltage/current rating for my application, but found one too many ratings. See attached snip. I'd think that the two ratings that matter are "rated thermal current" and "rated insulation voltage" which tells the user the maximum voltage/current the relay can withstand.

What is "Min. low energy permissible load" telling me? Why is there an HP column? You would never use an ice cube relay to drive a motor. There are ratings for "general purpose" and "resistive"; which one do I take into account?


texts: Infrared LED, color cover/dome interactions?

texts:
Might not be the best forum, but sort of at a loss of where else to try...

I'm trying to find a cover/dome for an IR LED project that I'm working on. The only thing I've found so far is:

http://www.goldmine-elec-products.com/prodinfo.asp?number=G15340

...which is a clear green acrylic dome. My question is, would the green color block/interact with the LED signal in a negative way?

If anyone else has any links to a similar dome/cover for IR LEDS, that would be an acceptable answer as well. :-)

THANKS!


texts:
I'm working on generating an expression for output voltage v0 in terms of v1 for the op-amp below.

I was hoping you guys could walk through my logic and make sure I'm analyzing this correctly.

The op-amp is providing negative feedback to the inverting input which allows me to assume that current into the op-amp is 0 and the voltage at both input nodes are equivalent.
The voltage of the non-inverting input is 0V because it's connected to ground which also makes node B 0V.
Therefore, the voltage drop across R1 is v1 and the current through R1 is consequently i1=v1/R1.
Since current going into the op-amp is 0, the current i1 must also enter R2 making the voltage v2 across the resistor v2=i1*R2=R2/R1*v1.
The voltage drop across across R2 makes the voltage at node A va=-v2=-R2/R1*v1.
Using Kirchoff's current law at node A, I can generate an equation for v0 in terms of va and replace all the va terms with va = -R2/R1*v1 as found in step 5.

My final expression is $$v_0=-R_4v_1(\frac{1}{R_1}+\frac{R_2}{R_1R_3}+\frac{R_2}{R_1R_4}).$$

Even better, if there's some way for me to check/assess my answer for these types of problems, I'd like to hear it.


texts:
I'm trying to make a simple astable circuit. It should be one of the easiest ones in history of electronics, but I can't figure out what's wrong with my design:

simulate this circuit – Schematic created using CircuitLab

The output voltage remains too low. About 1.5 V peak to peak.

(For my application this is less important, but maybe it could be useful to note also that the calculated frequency differs from the real one of about 30 KHz.)

I tried a different power supply and also a different ne555 IC.
Could someone please explain to me why the voltage is so low?


texts: Separate two batteries getting charged by one charger with diodes?

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I've got a robot that I use two batteries on. One of the batteries power the servos and engines and the other is for the digital boards.

The servos need 5 V.
The control board and LCD run on 5 V.
The engines use 12 V.

Both batteries are identical 12 V packs (3x 18650) each with their own BMS.

The robot is using DC-DC 12 V to 5 V step down converters to get appropriate voltages to the different parts.

I want to be able to charge both batteries from one 12 V source but also keep them isolated so the motors battery cant take juice of the digital battery and vice versa.

Can I use diodes on the 4 lines (2+, 2 Ground) coming from the single charger two for each battery to accomplish this separation?

Should I put a diode on each side of each battery or for example only on the ground or volt?

Is there a better way?

The lines between the Arduino and the controller don't link the batteries in any way. But the common charged does which is the problem I want to solve.


texts: How to appropriately test Ethernet hardware?

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How should I appropriately test the Ethernet of my device? I have some ideas:

Measure signal integrity between the MCU and the PHY or Switch devices (like RMII)
Measure the signal integrity of the proper Ethernet signals like TX+/ TX- and RX+/ RX- (measure, voltage levels and rising/fall times)

Should any of the above be sufficient to say the Ethernet, in electrical terms, is good in my device? What should be the criteria?


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I decided to use IRFP460 in a two-switch forward converter. This Mosfet can dissipate 280 watts. Can I get 1000 Watt from my converter?

As a general rule how much power a Mosfet can transfer with respect to its maximum dissipation loss?

I concluded that the mosfet can dissipate a derated loss power at a specified temparature if thermal resistance from junction to ambient be a required value; eg 2 c/w for 20 watts at 100 deg. Celcuis of case temperature.
Is it possible?


texts: Fluctuating digital input on arduino uno r3 when connected to Photocoupler

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I am trying to use a Photocoupler 4N-25 with an arduino uno r3.

I connected the collector to +5volts and the emitter to ditital pin 0.

Now, since there is no voltage applied to the gate and I haven't even connected the other side of the photocoupler (diode) with anything. Shouldn't it have an indication of LOW in the serial monitor? Instead it fluctuates between 0's and 1's.

I also gave it a try with the gate grounded, nothing...

I tried with a resistor to limit the current to the arduino, nothing...

Any suggestions?

EDIT

By trying out the circuit of @Passerby the input pin was high.
when i turned the gate High the pin went low.
All is good so far.

what i want now is this depicted below.

when i replace the opto-isolator with a simple led (D1) it works. i tried it out.

The problem now is that the led in the opto-isolator is not bringing the gate high. why is this happening.

keep in mind that i only want to use this opto-isolator for this circuit.

and correction the capacitor is 150nF


texts: How are FPGA's configured when operating independently?

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I have a DE0 Altera board with a Cyclone III FPGA from my VHDL class, and I want to learn how to use it in an independent device. Right now I have a Raspberry Pi and wanted to try playing with using those two together, but the problem is the way we learned to use the FPGA in class involves loading the VHDL design through Quartus every time, the file seems to be lost without continuous power.

I asked around and someone mentioned that in an embedded system, the .pof or .sof would be saved onto an external memory and the FPGA reprogrammed on startup. Can someone explain what the process behind this is? Do I need to build a JTAG programmer circuit or use a microcontroller to pull this off? Can I maybe use the SD reader on the DE0 board to hold the .pof instead of buying an EEPROM chip? Are there resources available to learn how to do this?


texts:
I've partaken in an experiment where I am looking to create the most efficient way to conduct water electrolysis.

My only need is that I don't trip a breaker. I will be running at 120vac, and likely a 15 amp breaker.

I've been looking at resistors, and I understand the ohms aspect. I am aiming for 10 amps for the sake of saftey( I know this is still lethal, but 15 leaves no room for any other devices on the breaker), and will need a 12 ohm resistor.

I've looked up some guides on resistors, and noticed information on wattage or temperature limits. All the information on them has been very vague for me.

Can I use any 12ohm resistor for this, or does it need special specifications for my workload?

Still learning.
Thank you.

Edits:

Going to oxidize iron in 2 litre container. a few 6 inches between electrodes. Water is just tap water, might add salt ( 5 g/l?) to help it out. No idea how the complications of electricity work, so bear with me.
Going to use copper, I know I need a larger cable though, I don't understand the width system yet, learning.