texts:
I am having problem to verify what an app note (AN068) explains to calculate Balun values. I would appreciate if someone could tell me what/where am I doing wrong?

The summary of the RF part:

Blue part is the DC blocking cap, C10-L1 and L3-C11 are Balun, the grey part is PI network. The IC's (CC2500) datasheet defines the optimum load at RF_P and RF_N as 80+j74 ohm.

From figure 6 on page 7, it shows the differential circuit, and the below figure (figure 7) shows the single part where the impedance is divided by 2.

"It ignores the dc blocking cap as the values are large". It marks the trace to take the impedance of the trace in calculation. 20 + j0 is the Thevenin equivalent impedance (Zout).

Here is the Gerber view of the design:

The app note suggests to calculate the impedance of the traces (from pad to pad) for the balun part. Both paths have the same length. The left path: C9 to L3: 0.192mm; L3 to C11: 0.177 mm; C11 to C12 = 0.185 mm; the total length is 0.554 mm. The width of the trace is 0.254 mm, the gerber document says that the FR4 thickness is 1.6 mm. The app note says to enter permittivity for 2.45Gz as 4.1, tan loss 0.0155.

I enter the values measured from the Gerber files and the app note to NI's line calculator:

It shows 135.674 ohm impedance and 2.67941 degree electrical length.

Then as the app note suggests, I define the source impedance as 40 + j37 ohm (blue circle) and load impedance as 20 + j0 ohm (red circle) on the Smith Chart (there is a small circuit representation on the left bottom side). After that, I added a transmission line and define the parameters from the line calculator (135.674 ohm, 2.67941 degree) (the program does not allow to enter precise numbers, therefore I select the closest possible values). Finally, I added a shunt capacitor with 1pF and 1.2nH series inductor as the final design uses those values.

However, it get a different smith chart that the impedance doesn't match as the app note shows.

I get the it matched if I enter 335 ohm for impedance of TL and keep the other values the same. I need to enter weird values in order to get the 335 impedance on the line calculator.

Where do I do wrong?

EDIT 1: I guess the app note says to measure the length from the radio pins, then MCU to C9 is 0.506 mm. The total length is 1.06 mm. It only changes the electrical length to 5.12667 degree which is almost the same smith chart as I was using 4 degree (smallest possible on the program I use) on the above smith chart.


texts: Can i replace 1n4148 with 1n4007 in this circuit (pic Programmer)

texts: I want to conceive a pic programmer i found this circuit but  i didn't find 1n4148 can i remplace it with 1n4001/1n4007 in  this circuit It affects the pic or dysfunction of the system in speed ou current


texts:
When I have to calculate a Thevenin's equivalent circuit which has a current controlled voltage generator, what should I do to calculate the open circuit equivalent voltage to the terminals in question? Is there any difference between a circuit that hasn't any controlled generators? Can you guys give me some examples? Thank you in advance,I  know that this could be a stupid question for those who had studied circuits for a long time!

Anyway, here is the circuit i was trying to solve, if you guys want the data just ask


texts: Non-Electrical-Engineer-Here: Can I use a 5v 2A power supply with any 3.3V regulator?

texts:
I have a 5V 2A DC power supply I plan to power a custom arduino with. However, I'm also using a NRF24l01+, which requires 3.3V. So, I'm in the market for a 3.3V regulator, but I'm unsure of which one to buy. Some have output current of 500mA, and some I've seen that cost more have output of 3A. Does it matter which one I buy?

I'm partially worried about frying the NRF24l01+. But I don't have enough of an understanding of voltage versus current and what can connect together. I'm more of a plug-and-play kind of person.


texts: FT232RL usb issue - not accepting an address

texts:
Hi I'm trying to build my own custom arduino board. The FT232rl doesn't want to accept the address given to it. I've wired in all the gnd and vcc wires. Including the gnd wire for the usb port. I'm getting this error in my dmesg

[23289.780022] usb 4-3: new full speed USB device using ohci_hcd and address 75
[23290.201047] usb 4-3: device not accepting address 75, error -62
[23290.370021] usb 4-3: new full speed USB device using ohci_hcd and address 76
[23290.790020] usb 4-3: device not accepting address 76, error -62
[23290.790030] hub 4-0:1.0: unable to enumerate USB device on port 3

I've wired pin 2 of the usb port (D-) to pin16 and pin 3 to pin 15. Am I not correct in saying the FT232RL has a build in usb transceiver so therefore it should be able to register as full speed device by itself? I have a ttl converter using the same chip that registers as soon as I plug it in.

According to my scope the chip is oscillating at 38MHZ so I can only assume I didn't damage it when I was soldering it. I have to admit this is the first ssop I've soldered.

Wired the same except I've not wired in the tx/rx. I've also wired the test pin to gnd because the  DS told me to. Windows detects as unknown device but in device manage it said it's been disabled because the device reported issues.

http://docs-europe.electrocomponents.com/webdocs/0aa3/0900766b80aa32f9.pdf
The same ds sheet on rs website which is where O brought the chip from


texts:
I'm having trouble getting a simple blinky project working using the on-board LED's on the TIVA TM4C123G evaluation board. I am using the header files from the driver libraries so I don't have to write directly to the registers as much anymore. However my problem is that I am getting a compilation error saying  (cannot open source input file "header file names here": No such file or directory). I am unsure what I am doing wrong. Is how I have saved the header files and included them correct? What is causing this error message?

By the way if I comment out the first include directive, I get the same error messages for the header files hw_memmap and gpio. I have copy and pasted the header files from the driver library folder into the folder for this project called Code1.

Below is my C file containing the main program:

#include "inc/tm4c123gh6pm.h"
#include <stdbool.h>
#include <stdint.h>
#include "inc/hw_memmap.h"
#include "inc/gpio.h"

#define RED_LED     GPIO_PIN_1
#define BLUE_LED    GPIO_PIN_2
#define GREEN_LED   GPIO_PIN_3

// The error routine that is called if the driver library encounters an error.

#ifdef DEBUG

void

__error__(char *pcFilename, uint32_t ui32Line)

{

}

#endif

int main(void)

{

    // Setup the system clock to run at 50 Mhz from PLL with crystal reference

    SysCtlClockSet(SYSCTL_SYSDIV_4|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);

        // Unlock the Port F register.

        GPIO_PORTF_LOCK_R = 0x4C4F434B;

        // Enable the Port F commit register.

        GPIO_PORTF_CR_R = 0xFF;

        // Enable and configure the GPIO port for the LED operation.

        SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);

    GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, RED_LED|BLUE_LED|GREEN_LED);

        // Loop Forever

     while(1)

    {

        // Turn on the LED

        GPIOPinWrite(GPIO_PORTF_BASE, RED_LED|BLUE_LED|GREEN_LED, RED_LED);

                // Delay for a bit

        SysCtlDelay(2000000);

        // Turn on the LED

        GPIOPinWrite(GPIO_PORTF_BASE, RED_LED|BLUE_LED|GREEN_LED, BLUE_LED);

                // Delay for a bit

        SysCtlDelay(2000000);

    }

}

Below is a screenshot of my Keil project showing the error message for the header file and all my include files inside my C source file that contains the program:

Also here is a screenshot of the header files being saved in the same location as the C source file that includes them:

EDIT

Peter Smith's comment solved my issue. I had the file name typed in wrong in the program so it was searching in the wrong directory for the header files.

However that issue is fixed, but when I tried compiling once again I got these 5 error messages as seen in the screenshot below. I am confused as all these functions are defined in their header files. Also this time I created a new project to see if it made a difference, hence the project name changed from Code1 to Testing. But they are virtually identical.


texts: What is the type of this legacy motor and how is it supposed to be controlled?

texts:
A friend of mine is going to give me an old Dayton 8F047 which I would like to recycle, but it is now obsolete and I cannot find anything other than a schematic which is reproduced below.

simulate this circuit – Schematic created using CircuitLab

It looks like a separately excited DC motor aka "universal motor", which also works with AC, and I'd just need to wire the auxiliary and main windings in series to make it work I think. I assume the start switch (which is really illustrated like that...) is a physical external button (please shout if it is an internal component essential to how it works), but I can't make sense of the so-called "protector" (which is illustrated as a circle) which is in the way of the main winding, so I'm confused now. I don't want to try things randomly and burn it...

I found this and that on the internet, but I don't know how grounding either end of the auxiliary without supplying it with any power can change its direction, and I don't know what's inside the UL Limit.

What is this type of motor and how am I supposed to control it?


texts: How to convert temperature to an ON-OFF state

texts: Suppose I want to build a simole circuit that reads the temperature as a voltage from the sensor. If the voltage gets below a certain value, turn the heater on (1). Else, turn the heater off (0).  How would I build this circuit?


texts: Calculating power consumption in portable air conditioning unit

texts:
Apologies for this likely very simple/stupid question.

I have a portable AC (air conditioning) unit that's supposed to be "energy efficient". On the back of the unit, it tells me some details about the unit's power consumption:

Voltage: 115 V-60 Hz
Current consumption: 11.4 A
Cooling capacity: 4100 W (14000 BTU/h)

So here's where I'm a little confused. I see the 4.1 kW and I'm a little confused, because my limited understanding of electricity would be that the power consumption shouldn't exceed the voltage multiplied the current (in this case, 1311 W). Does this mean that my unit is drawing 1.3 kW/h of electricity, or 4.1 kW/h? If it's the former, how does it output more than 3x the power that it draws in?

Also, I was wondering if my power consumption remains constant with this unit plugged in (whether at 1.3 kW/h or 4.1 kW/h), or if it will fluctuate based on the settings? In other words, are the numbers listed on the unit supposed to represent how much power it will draw in no matter what, or does that represent the maximum amount of power it will draw (meaning that it could draw less if I, for example, didn't need as much cooling)? Apologies for my limited understanding here, but just want to make sure I can get a roughly-accurate estimate for my upcoming power bill.


texts: Can you desolder and upgrade RAM in Pi boards?

texts:
Friendly Electronics has come out with a great small compact but very powerful board. It is called the Nano Pi fire 3. It has 8 cores which is great for programers like myself who want to utilize the cores for clusters and multiprocessing AI machines. However, it only has 1 GB of ram. Therefore, one of the processes I am trying to run can easily take up the ram of the entire board. It is fairly easy and straight forward to attach a cheap memory stick compatible with the board to allow for more swap space. This would be done so that the program can continue to run and not cause the board to entirely run out of memory. However, swap space is slow. Especially because the Nano Pi only allows for a USB 2.0, there is no real fast way to utilize the swap space. Unless I am wrong, then please correct and teach me how I would use the swap space in a faster manner. Now, assuming I am correct, the only way to truly speed up the board would be to actually give it a better physical RAM card. On a Raspberry Pi this is impossible/if you don't REALLY know what you are doing dumb. The reason I say this is because the Raspberry Pi places their RAM cards directly on top of the CPU's. I am not going to post the schematics of the Raspberry Pi, but you are welcome to look them up and fact check me. However, the Nano Pi and other boards from Friendly Electronics don't do this.
(here is the layout of the Nano Pi Fire 3):

This image is from http://wiki.friendlyarm.com/wiki/index.php/NanoPi_Fire3
As you can see, the board has 1 GB of DDR3 RAM. It is easy and fairly inexpensive to buy a 16 GB chip of DDR3 RAM. Which is a very viable solution for myself and probably many people trying to get around their issues with slow boards. Is it possible to achieve what I want to do?


texts: Hacking DSLR battery to power camera from power supply

texts:
I would like to power my DSLR for long captures with a power supply. I know the voltage and inner structure of the official batteries. The battery has 2x 3,7V cells inside with a circuit. People worked on this issue report that the battery's circuit is there to protect shortage or high current draw for protection. The circuit also provides authentication and ID to the camera. If this is not provided camera seems to know this and display error message.

What I am thinking doing now is to use manufacturer's own charger to provide the power, while battery is still attached. Meaning, that the power supply will simultaneously "charge" the battery and in parallel will supply power to the camera. The authentication pin can this way be connected to the camera.

I don't want to kill my camera, therefore I am asking, if this can go wrong in any way?

PS: I will keep the actual battery outside (for the authentication pin), while a 3D modeled/printed power supplied fake battery will go into the camera.

Plan (blue line: authentication pin):

Edit: I forgot to mention that there is an adapter sold by Nikon to fit into the battery hole and power via external power supply. However, >$45 is too expensive for dumb power supply. If I can 3D print my part, then I can have the same thing for <$5. This is also a matter of principle.


texts: power supply remote sense protection resistor value?

texts:
There is often a 100 ohm resistor between the +sense and +ve and between the -sense and -ve outputs of bench power supplies. This protects the output from high voltage if the sense wires are accidentally disconnected. So why are these resistors low value like 100 ohms? What if it's 1K?

I'm making a 6V power supply and can't seem to see much difference in the output whether it is 100 ohms or 1k. The output voltage always falls if the sense wire gets disconnected, whether the resistor is 100 ohms or 1K.

Also, it seems 1K is better, if the actual power line gets disconnected. The 1k will survive, while the 100 ohms will burn up, possibly taking the sense wires with it.

So, what am I missing?

edit:

I think the question was not clear. There are no feedback resistors involved here. These are the resistors I am talking about: Rs and Rs shown below. They will burn up if they are low value and the output cable is disconnected (they are usually 100 ohm 0.5 watt; sometimes even 5 ohm or 10 ohm). But they will not burn up if they are 1K 0.25W. Image from here and here.

I cannot seriously think the resistor is low value to decrease noise. There must be dozens of much higher value resistors in the power supply itself. And this is not a feedback resistor, it is a protection resistor (protecting against inadvertent high voltage at the output if the sense wires are accidentally disconnected). Almost no current should be flowing through them during normal operation.

PS: my power supply has only the +ve sense wire, so will have only the one resistor. Ground return is directly connected, no sense wire or protection resistor.

update: to make it more clear, this is the output stage that I currently have (after putting in the back to back diodes). The power supply is rated 6V 1A, but with sensing failure may go upto 9V 1A. The 40m ohm resistance comes from a dual mosfet protection system. The 1N5408 is to protect against accidental high input voltages from output (and prevent the crowbar from nuisance tripping). It can be bypassed. The 20m ohm is output cable resistance. Please ignore the 10k resistor, it is temporary. Local sensing can be done before the mosfet switch or at the load (indicated by the unconnected bent wires going from the op amp). Circuit works fine with all resistor values. If I were to put in parasitic capacitance to simulate, where should it be?


texts: Shockley's Equation for JFET transistor in Proteus

texts:
I'm trying to do a simulation using Proteus for the NJFET Transistor ...
But when simulating the Shockley's Transfer equation i get a wrong curve

And here is graph's properties


texts: Ring oscillater for measuring the threshold voltage variation

texts:
I have to write a paper about a threshold voltage variability detector using a ring oscillator.

I have a circuit like pictured above, and I have to write some things about how to test it; basically:

What instruments I would use
What type of measurements I would do and
Some conclusion.

I'm not sure what to write because I'm not sure also what the other modules from the picture are supposed to do. If you could help me with that I would appreciate it.


texts: Is it possible to transmit square waves EM signal through air?

texts: Can we transmit any signal other than sinusoidal through air, if yes how and if no why ?


texts: Connection Ethernet MACs without using a PHY device

texts:
I am designing a board that utilizes an NXP LS1046a processor and multiple Kintex Ultrascale FPGAs. The plan is to connect the processors up to the three FPGAs via the 1Gbe links.
Since they are all on the same board, the plan was to try and connect them up without using any PHY devices, only MAC-MAC communication.
Has anyone ever done this? Do you know if this will work?
Any insight would be appreciated!


texts: Improving a SRAM-based memory cell by reducing number of transistors

texts:
I'm working on Emulated version of a memory cell. It is a volatile single-bit memory.

It uses 4 NAND gates to store one bit. I want to connect several of those memory cells together to create one byte of RAM.
Each NAND gate uses 2 transistors, so, in total - it uses 8 transistors. I'm facing a problem because of it. I have to reduce the number of transistors somehow. I tried to find out a solution and saw DRAM schematics. But I can't use capacitors in it. I want it to have only transistors and resistors.
Is it possible to reduce the amount of transistors required by replacing NAND gates or in some other way?

More details about the memory cell I'm using can be found here


texts:
How is a sine wave created by an oscillator?
I mean generally, we have a voltage that changes its polarity according to frequency, but at the output we have a sine wave (example Wien bridge oscillator) - how does this happen?
Can anyone prove that with mathematics or ideas that the output wave is a sine wave?


texts: Same DDR3 total capacity, different chip capacity configuration, speed different?

texts:
Let say I want to have 1GB DDR3 in my board. I could use:

2 pieces MT41K256M16 – 32 Meg x 16 x 8 banks
1 piece MT41K512M16 – 64 Meg x 16 x 8 banks

Will configuration #1 be faster since 32 data buses can be accessed at the same time? If not why?


texts:
The Atmega328p datasheet recommends the following circuit to work with its internal crystal resonator:

simulate this circuit – Schematic created using CircuitLab

I can't find any recommendations on the type of capacitors to use.  I think the reasonable options are mica and thin film. Maybe also ceramic NP0 (emphasis on the NP0 type), which is a lot less expensive.

Any advice?  I tend to believe that either type is ok, mica and thin film probably being the absolutely safe bet?  Again, any comments will be appreciated.


texts: Basic N-MOSFET Circuit Simulation Results

texts:
I am confused about some features of the very basic N-MOSFET circuit shown below:

Which I also created in an online circuit simulator you can find here.

The problem is the VDS value, which the simulator reports to be about 11.99V and the voltage drop of the resistor 11.03mV.

I've found consistent results in all the 5 simulators I've tried, both online and offline.

I've created a real-world circuit using a N-MOSFET STP100NF03L-03 and I've found that resistor voltage drop is about 12V and VDS is near 0V.

So the the question: anybody can tell me why this difference?

EDIT

I have to apologize, I misreported the problem. The simulated circuit has a 12V power supply and a resistor 0.01 ohm, while in the real-world example I used 9V and a 100 ohm resistor.

The measured voltage drop of the resistor was about 9V, while VDS was about 0V. Now I realized that STP100NF03l-03 has a very low RDS while the simulation includes a generic N-MOSFET which values are not known, but likely RDS is generally far greater, even greater than the simulated resistor value, thus leading to a VDS greater than the voltage drop across the resistor.


texts: Most cost effective way to power a bunch op amps +/-12V supply rails from +5V

texts:
I'm searching for the most cost effective way to supply +/-12V for 12 TL084 op amps. Reading in the datasheet, it seems they have a typical current output (with load) of about 20mA. So, 12 * 20 = 240mA. Assuming that is correct, I only need about 300mA of current draw from the +/-12V supply.

Here are the solutions I've come across:

Recom Power - RS6-0512D: This modules takes in 5V and provides +/-12V output. Pretty straight forward but a bit pricy, around 21$CAD.
Using 1 TC1044S charge pump per 2 op amps and an external 5V to 12V boost converter for the whole deal. Total cost: 1.45$CAD (TC1044) * 6 = 8,70$. Add around 4$ for the 5V to 12V converter = 12,70$CAD for the whole thing.

Any simple solution I haven't thought of? Are these 2 solutions a standard way to power a bunch of signal processing op-amps? Is it a problem even worth solving with a chip or should I go down the road of implementing this myself? Is there even any advantages to implement this myself?


texts: Is this a reference of an AC/DC REGULATED adaptor?

texts:
I need to choose an 230 VAC / 12 VDC converter which is regulated, that-is-to-say I need the voltage to be 12 V with a current of 0 to 5 A.

I found this one because it is the cheapest (price really matters) : https://www.mouser.fr/datasheet/2/260/GSM60A-SPEC-1147092.pdf

But I do not see any information regarding its regulation. Is it regulated ? Generally speaking, how do I know in datasheet if an adaptor is regulated or not ?

Thanks.


texts: Will a lower resistance potentiometer improve a panel meter scale reading?

texts:
I have an analogue tacho/RPM panel meter on an auto distributor tester, c1950s. This is not the original meter. It has two scales 0 - 6000 rpm and 0 - 1000 rpm, with a toggle switch between the two. When running, the max rpm on the scale I can get is 2000 rpm, no matter how fast the disc spins, the meter will not go past this mark. I have removed the meter and fitted it to a similar machine where it works perfectly.

There is a 500 ohm linear potentiometer in the circuit, which I can adjust the needle up or down, but not past the 2000 rpm mark. I tried a 2000 ohm pot I had, the needle would only move up to 3 - 400 rpm on the scale. This meter was changed by a previous owner at some point, but the pot appears to be original.

I do not have a circuit diagram, have changed out all capacitors, disconnected resistors and tested according to colour bands. So, if I were to fit say a 100 or 150 ohm pot, would this allow the needle to swing further across the scale. I use a digital laser meter to check the disk speed against the meter reading, up to 2000 rpm is appears to be accurate. I’m a novice so any advice is appreciated, thanks.

Thanks for your response Transistor. The meter is a moving coil type, I have no Written information of the unit. It is an Allen Syncrograph, model E137, distributor Tester. I have everything else functioning apart from the tacho meter. Given a higher resistance pot would not read much on the meter scale, I thought perhaps a lower resistance pot would read higher on the scale. I appreciate any comments, thanks

Thanks for response Reroute. Attached are images, the circuit board is attached to the two terminals on the back of the meter. The three terminals on the POT are connected, I will check which resistance gets the higher reading on the scale.
The other unit model E-319 the meter works on, uses a 6vdc car battery to operate the gauges, with a POT to SET the needle to the RH side of the meter scale before using. 240vac to run the motor.
This unit E-137 is 240vac, no battery.


texts: A question about ultrasonic sensors in general

texts:
Do ultrasonic sensors send out waves in a straight line, all the way to a reflecting substance (if any) and get reflected in the same line back to the receiver?

Or do they send out a wave which gradually becomes wider?
If the answer is case (ii), could someone please tell me how they work?
This is for a project I am doing about using an ultrasonic/IR/laser proximity sensor.

Do any of the available distance sensors send waves in straight lines, to the reflecting substance and back?

Thanks a bunch.


texts: In a metal wire, do protons flow in the opposite direction from the positive terminal, like electrons do from the negative terminal towards the positive terminal?


texts:
I am designing a current source that is going to control LED. With help of the DAC and microcontroller, I generate a voltage that goes to OP-amplifier, and afterward, I am opening my NMOS transistor. I have attached my schematic of the simulation below. I want to add a photodiode power sensor for the better accuracy of my circuit. Now my question is how could I simulate the photodiode relating to the luminosity power that my LED is emitting. Is it possible that I could connect these two in LTspice? I am new at LTspice and I would need it for my university project. I thought I could use an arbitrary behavior current source, using it as I would simulate temperature. My photodiode power sensor is S130C from Thorlabs. I would be thankful for any advice on how could I realize my problem.
Thanks

Current source schematic and LDO

Response graph of my photodiode power sensor


texts: Low DC Current (~ 1.2 A) SPDT for Arduino

texts:
A little explanation first.

I am working on an Arduino project where I want to measure photovoltaic power generation by measuring voltage and current of an array of 10 small PV modules at 5.5 V. Maximum current output is 1.2 A. This PV array is powering up the Arduino while charging a battery.

I have successfully used a voltage divider to measure PV voltage, but I am having a really hard time in measuring current.
I tried using a ACS712 hall sensor but the current draw is too low and the sensor doesn't identify it.

The question follows.

So I would like to use a resistor with a low ohmic value to measure voltage drop across it and estimate current draw.

Since using a resistor to measure current draw is the most inefficient circuit I can think of, I would like to use an SPDT relay to temporary switch on the "resistor circuit" and measure current. After the measurement, I would switch off the resistor circuit and use the normal circuit.

On another topic I read about the SPDT analog switch TS5A3157 by Texas Instruments, which does exactly what I am looking for.
Only problem is it can only work with currents up to 100 mA, which is not enough.

So, could anyone recommend another SPDT?

Or should I switch to another type of switch (ahah), such as a mechanical relay?

Many thanks for your help!

Additional Notes

As explained above, I am measuring a maximum current of 1.2 Amps (from PV Panels).
Nonetheless, I would say typical current draw will be around 50 mA when all of my sensors are on (temperature, LDR resistor, pressure sensor).

I read somewhere (here) that a 4.9 ohm resistor could work pretty good: 1 mA of draw translates to 1 mV of voltage drop. So 50 mA would mean 0.24 V voltage drop, which is inacceptable in my view.

That's the reason why I thought about a switch: to power the resistor only for a few seconds in order to take a measurement.


texts: About the difference between ambient temperature and rise temperature in pcb design

texts:
When to use to
Pcb trace width calculator,there are two factors,ambient temp.and rise temp...what is the difference between them?


texts:
I'm designing a smart bin for my paper and would like a sensor that continuously monitors  the battery level in real time and in percentage value and then sends the data to the administration office.
What sensor can I use? And how can the percentage value be obtained?


texts: ADC oscillation problem with inductive load

texts:
ADC in question is onboard ATMega168 micro controller. Relevant parts of the circuit look like this:

simulate this circuit – Schematic created using CircuitLab

Now I know AVCC is recommended to be connected through a low pass filter, but the physical connection is very close to VCC which has the 0.1uF C1 already. Super high precision also wasn't really required.

Now, everything works fine if LLoad is switched off. But when switched on the value being returned by the ADC increases enough to result in a different value and also oscillates enough to rapidly jump between two values.

What can I do to get LLoad to stop influencing the ADC result so much?

Edit: I've changed the schematic to have more relevant parts and I will now provide some exact values for what is going on.

LLOAD is a pair of DC motors.

THERM (which is a thermistor) provides a steady reading under all conditions.

POT (which is a potentiomitor used to set the target for THERM) oscillates as follows:

LLOAD OFF - ADC: +/- 3 (+/-0.14mV)
LLOAD ON - ADC: +/- 10 (+/-0.4mV), also the ADC value immediately jumps by +20 (0.9mV)

LLoad and POT share a physical return path as in the diagram. Also LLoad is not switched by the MCU nor does it need to be switched during operation. But the +/-10 is a bit too much oscillation. The +20 jump could be worked around though it's a bit annoying.


texts: How to power a Arduino Yun with a 6V battery?

texts:
I would like to power my Arduino Yun board with the following battery:

Arduino Yun has a VIN pin that represents the input voltage to the Arduino board. The official documentation says:

  Unlike other Arduino boards, if you are going to provide power
  to the board through this pin (VIN), you must provide a regulated 5V.

What I have to make (exactly)?

Note: I have some diode, resistor and other basic component...


texts: reverse recovery current of 2 different diodes in series

texts: Will the reverse recovery current that both diodes see be the super-position of both diodes' reverse recovery currents?


texts: Re: decoupling capacitor design calculation

texts:
I was searching a bit about the decoupling capacitors.
All I was able to find is electrolytic capacitor is used for low frequency noise filtering and ceramic capacitors are used for high frequency noise filtering.
I could not find any formula to determine the values for the same.
Can someone please guide me on the approach to be followed and formula to determine the values?
PS: I am aware that multiple electrolytic caps are used because of the ESR and the ESL of the capacitor.


texts:
If I have a plug that is rated 10A @ 250V AC, is it safe to assume I can use it at 10A @ 12V DC? Could it be used at higher current or should its maximum be lower for that matter?

Thanks!


texts: Is there a way to save state in a very low power way?

texts:
I basically want to determine if power has been totally disconnected in a low power device I am making that uses an Atmega328 chip.

The theory is that when power gets first applied the ATmega will power up, calibrate and take some readings then power down again. The rest of the circuit will still be powered until the chip wakes up again and takes more readings.
What I need to be able to determine is if the battery was disconnected or not. If it was, I need to do a calibration again; if it wasn't, then I just take a reading as normal.

Is there any way of doing this which takes as little power as possible?


texts: Can I use a halogen transformer as a power supply?

texts:
I have an electronic transformer which is meant to be used to drive a 12v halogen light. The specification on the  electronic transformer box says 220-240VAC input, 12VAC output 20-60W.

When a 50W halogen bulb is connected to this electronic transformer the voltage across the bulb is approximately 10.5VAC.

Is there a way of using these low cost electronic transformers to supply power to a small single board computer?


texts: Does a hole through small gauge wire affect current and voltage to the source?

texts:
I put a hole with a staple trough a small wire (with the black stripe).

The line is coming from a solar panel, so not sure if that changes things....?

How will this effect current and voltage?


texts: What is purpose of Balun transformer in RF front end

texts: In following RF receiver circuit (30 MHz), two wires of a dipole antenna are connected to SMA connectors and the signal goes to an amplifier. I don't understand what is purpose of this balun transformer in circuit. If anybody can explain?


texts: Where to simulate and test Microprocessor designs?

texts:
I'm reading book on computer architecture by Patterson and Hennessy. Now I'm much interested in designing a real-time working microprocessor. But i didn't have any idea where to start from! I started to learn VHDL so suggest me something from where i can design processor from gate level and implement it on real working hardware.

EDIT: Since I mentioned that I'm a bit familiar with VHDL so simulation using VHDL will be more easy. But what i am actually concerned is that if VHDL simulates my design perfectly will this design also work well on real time hardware(FPGA Board)? What are the precautions to be taken to ensure same OR is there any other software(tool) which is more nearer to reality and considers most of real time challenges in simulation?
    To be more specific i want to know how engineers at Intel, IBM, Tilera or AMD design, simulate and verify their Processors designs? What are those techniques and processes?


texts: Determine material of Zener's diode based on its characteristics

texts:
I have a plot log (I) = f(U) for a few diodes: Silicon diode, Germanium diode, some LED and a Zener diode. I need to determine the material, from which the Zener diode is made based on the positioning of its characteristics. What parameter should I look for to determine it? I thought about checking the band gap somehow, but I am not sure whether it can be determined by just having a plot log(I) = f(U).

And if I know the difference between voltages (for specified current) of two diodes , let's call them A and B, and I have some information about diode A (including its band gap), can I calculate the band gap of the B diode?


texts: Error amp compensation on pwm controller

texts:
I'm trying to build a half bridge smps for 325 VDC to 30 VDC using SG3525 controller IC.
I have no idea on how to use the error amp on this chip, especially the compensation pin.

[

[

I have seen in some designs the compensation aka "comp" pin which is pin number 9, grounded using a capacitor, in some circuits it is used for negative feedback as in op-amps, in some other design I saw it being directly connected  to inverting input, and in some other designs I have seen the comp pin connected to inverting pin with a parallel RC network.

My question is, how to properly use the above mentioned compensation pin in the error amp of SG3525??


texts: Is there a way to run MacSpice on the Terminal, similar to the Python interpreter?


texts: Can anyone help identify this mystery integrated circuit?

texts:
These were in a box belonging to my grandfather.
I don't know if it's relevant, but he worked at a navy yard. I'm guessing they're around 50 years old. Nothing comes up on google search.
I don't know if it's even considered an IC.
The ICs have the following markings:
CTS 7118 9-43 016-824-001


texts: What is the buzzing sound I hear via headphones when I touch my charging laptop?

texts: I noticed that when I'm wearing my headphones, if I touch my laptop that is plugged in to an outlet and charging, I hear a slight buzzing sound. What is causing that? Should I be concerned?


texts: Computational complexity of current netlist matching algorithms

texts: I understand that the problem of matching two netlists could be reduced to the graph isomorphism problem which is NP-intermediate. Apart from that what are the complexity results of some of the currently used netlist matching algorithm?


texts: can I charge Mobile battery using mobile charger directly?

texts:
I want to charge mobile battery of 3.7 v directly by connecting 2 terminals of charger(5 v output) to two terminals of battery. My questions are

Is IT POSSIBLE?
what must be voltage adjusted to charge 3.7 v battery?
Is there any circuit inside mobile phone charger already that will
stop charging, when battery become fully charged?
Is there any additional circuit required?
Is there any risk/precaution ?


texts: Is it safe to wire a telephone to a breadboard?

texts:
I am trying to connect a hardwired 2554 telephone set. There's only a few inches of slack wire coming out of the phone since it appears it was just cut there. I managed to get about half an inch of the coating cut out and then stripped the individual conductors for green, red, yellow, and black. I then connected mini-grabber leads from each and put them onto a breadboard, with green and yellow connected and red in its own row. My plan now is to use another set of mini-grabber leads to connect the green/yellow row from the breadboard to TIP and the red row to RING on a butt-set adapter I have which will get plugged into the phone line.
Far from optimal, but I don't have a free connection block at the moment and this seemed like a quick and dirty hack which ought to work.
On second though, I have reservations. I did some research and am having second thoughts. Some sources say breadboards can handle only 5V safely, others say that up to 50V at 0.5A should be fine.
Then, there's minigrabber leads, which are consistently rated for 30V AC or 60V DC. 30V AC is well below minimum ringing voltage, which is around 90V AC, give or take a dozen volts.
I believe ringing current is either 48mA or 480mA, less than half of the 0.92A limit for 22-guage wire. But strictly speaking, I'm not using any 22-guage wire, I'm just using minigrabber leads through a breadboard.
I called another telco guy I know and he said it should be fine, and not to worry about the 30VAC/60VDC limit for mini grabber leads since that's assuming a much higher current, but his analysis was mostly to the effect of "the wires in minigrabber leads and breadboards are thicker than 22 guage wire, you should be fine". Quantitatively, I can't find a good answer. I don't think this will blow anything up necessarily, but would there be any reason to be concerned about the setup (mini-grabber leads + breadboard)? I recognize the setup is far from ideal, but is there any real danger to this or not really?


texts: In my project I want to use some ceramic and electrolytic capacitors, I will need the capacitors be at least 10V rated, but what will happen if I use much higher rated capacitors (just to make sure in case of something went bad they don't explode!)?


texts: Why does this DC motor have such a wide range of power?

texts:
This DC motor has a power range of 9.0W-300W, while its voltage range is from 6 to 20 volts. Does this mean that its internal resistance is somehow dependent on the load? Or does the user determine the actual power with using a resistor in the circuit?

Performance Table

MODEL   ---- VOLTAGE ----  -- NO LOAD ---  ---- AT MAXIMUM EFFICIENCY -----  ----- STALL ------
        OPERATING NOMINAL  SPEED  CURRENT  SPEED  CURRENT   TORQUE   OUTPUT    TORQUE   CURRENT
RZ-735VA  RANGE      V     r/min     A     r/min     A    mN·m  g·cm    W    mN·m  g·cm    A
9517     6 - 20     18     20400    2.8    17990   20.9    149  1523   281   1265  12895  156


texts: What does the layer structures and the macro structre describe in a LEF file?

texts:
I want to know what is the exact format of a LEF file. For example, I have the following format of LEF file ... I want to know what the layer and macro structures describe. Also, how many layer and macro could be in a LEF file?

LAYER layerName
  TYPE ROUTING
  DIRECTION {HORIZONTAL | VERTICAL};
  PITCH {distance | xDistance yDistance};
  WIDTH defaultwitrh
  OFFSET {distance | xDistance yDistance};
END layerName
MACRO macroName
  CLASS {PAD | CORE}
  ORIGIN point
  SIZE width by height
  SITE siteName
  PIN pinName DIRECTION {INPUT | OUTPUT };
     PORT
     LAYER layerName
     RECT point point;
     END
  END pinName
END macroName


texts: Routing USB high-speed on two sided board

texts:
I found that it's always recommended to use at least 4 layers for high speed routing, but there are still some projects which uses only 2 layers for USB high speed.

I'm just a hobbyist, I cannot effort for high cost board. Can you explain me why some project like this one (http://www.pavouk.org/hw/audiosystem20/en_at32uc3a3256usbi2s.html) or this one (http://dangerousprototypes.com/docs/FT2232_breakout_board) can use only 2 layers board for USB high speed. How can I do like them? Is there any further materials about this technique?

Thank you very much.


texts: Underrated microswitch in consumer product odd?

texts:
I'm currently looking at modifying a coffee grinder for automation purposes and whilst tearing it down and inspecting the components I noticed the model of micro switch used for the start/stop button and 2 others physical sensors are only rated for 3A / 125VAC according to the manufacturer specs and I live in the UK so it's receiving 240VAC. (Doesn't look like there's any voltage conversion circuitry).
Is this odd, or because it's a low current load it's not an issue and standard practice?

Photos of PCB (originals here):


texts: What is the purpose of the diode in this diagram?

texts: If a diode causes resistance then the path of least resistance would always be to ground.  So what is the point of this diode?


texts: Can this analog speed regulation for a DC motor be used for this scenario?

texts:
I’m dealing with a part of a small project where a device’s(DUT in the diagram) rotor is rotated at a desired fixed/constant rotational speed for a while and slows down itself by disengaging the speeding mechanism.

A small PM DC motor(M below) is used to provide rotation to the device. So when the switch SW is ON, the motor shaft in a way couples to the device’s rotor and brings it to a constant speed. The device also outputs freq. proportional to its rotation speed. So this freq. channel is monitored via a scope and logged by a data acquisition hardware DAQ. So after engaging the motor to the device, by playing the motor voltage Vs I fine tune the rotation speed to a fixed value, lets say 40Hz. After a while of constant coupling and rotation speed I turn OFF the switch and the device slows down. Basically this way I measure the friction of the device bearings but that is not related to electrical part. Below is the illustration:

Now the thing is, the temperature of the closed system in yellow above is varied from room temperature down to subzero. So the test is made at different temperatures to find the temperature effect on bearings.

I have noticed that even Vs is constant, the motor speed varies like 3 to 5Hz at low temperatures and as far as I found out, coupling at different results different load on the motor; the friction increases and I have to fine tune the freq. by varying the Vs knob at each step.

I think I can live with 1Hz variation. First I thought to use PID with a microcontroller but the motor might jerk and maybe it is hard for me to achieve an overkill. For me the power consumption does not matter and was looking for something analog. And I need a fixed freq. maybe set by a pot. I have come across the following circuit example here. Can this circuit be used for slight load variations for a fixed rotational speed each time the motor is coupled to the device? I couldn’t come up with another simple solution.


texts: Clarification regarding batteries and ups

texts:
I am planning to setup a ups with 2 100ah/4h batteries next to my server setup.

Is it safe to work to work next to such high load batteries. Are there any health concerns that comes with working close to such high load batteries.

If there are any health concerns how can they be addressed.


texts: BeagleBone VS Arduino/AVR/PIC - benefit of running Linux?

texts:
Is there a reason that the BeagleBoards run Linux? Is there a certain advantage to doing so?

If Linux is used to host the Beagleboard units, what analog does the Arduino use?

I am working on a project for a competition in which I will implement a communication system as well as attitude calculation and data processing in the form of images and various sensors. Similar projects have used the Beagleboards. I have been trying to figure out why they may have done so versus a standard AVR or PIC micro controller, for example.


texts: Does the impedance of a PCB track matter if the length of the track is far smaller than the wavelength of the signal?

texts:
I have a PCB with tracks of no controlled impedance. The longest track is shorter than 1/5000 of a wavelength.  Does the impedance of the track even matter?

If not, then at what length would I need to start thinking about matching the track impedance to the source and load impedances?


texts: What would be the best way to limit mains (240V @ 50Hz) current? I want at least 1A of current. The output should be AC 240V at any frequency greater than or equal to 50Hz. It should be able to endure short circuit like conditions. I have tried dimmers (which instantly explode when connected) and fluorescent tube electronic ballast (too low current). I would be using this to power a hand wound toroidal transformer.


texts:
simulate this circuit – Schematic created using CircuitLab

I am currently trying to test my sound sensor, before I hook it up to a bigger project.

I have changed the code from digital to analog and from analog back, but nothing seems to work.

It has 4 pins:

Vcc = hooked through breadboard to 5V power supply from my Arduino
GND = hooked through breadboard to GND
AO = hooked to A0
DO = not hooked to anything

The built in LED is flashing red, so there is power going through it. I do not know the model name, but it is a standard sound sensor with a blue relay on top and a "microphone" component at the end.

The values displayed by it are seemingly random, the values being:

controlSensor: 10-12
Soundsensor: 54

The controlSensor value will change randomly with each reboot and either switch between 10/11, regardless wheter or not I am yelling into it (i.e it will stay at 11 between comlpete silence and me yelling) or 11/12.

The soundSensor on the other hand is static at 54.

Anyone have any tips for making this work?

Thank you,

int soundSensor = A0;
int ledPin = 3;

void setup() {
  // put your setup code here, to run once:
   Serial.begin(9600);
   //Sensor Setup
   pinMode(soundSensor, INPUT);
   //LED Setup
   pinMode(ledPin, OUTPUT);
   digitalWrite(ledPin, LOW);
}

void loop() {
  // put your main code here, to run repeatedly:
  delay(1000);
  Serial.println(soundSensor);

  int controlSensor = analogRead(soundSensor);
  if (controlSensor > 11){ //set the minimum value for activating the LED
    digitalWrite(ledPin, HIGH);
    delay(1000);
  } else {
    digitalWrite(ledPin, LOW);
  }
  Serial.println(controlSensor);
}


texts:
Fuses come in all sorts of shapes and sizes, assuming that i have a specification for its current and how fast i need it, what are the other considerations for choosing a fuse type?
Fuse types that i know of:

Blade automotive fuses
Ceramic SMD fuses
Radial glass fuses with holders
Fusible links


texts: I have bought a series of LED's. I'm working to make a bunch of modular floor panels and I need to be sure that if I flipped the wires around it's not going to screw up the LEDs on me. I'm basically asking can i do this and expect it light up?


texts: Can shutting of power bar damage cables or modem?

texts:
I switch off the power bar which has my modem and computer plugged into it a few times per day. Two days ago, a technician changed the wiring since my Internet completely stopped working for the second time.

I am wondering if turning off the power bar is damaging the cables or modem and is what caused the problem.

Can shutting off a modem directly from the power bar damage the cables or modem?


texts: How to transfer data between RS-422 and RS-485 ports?

texts: I'm relatively new to behaviors of serial ports such as RS-232, RS-422, and RS-485. I'm wondering how do you initiate data transmission between a system and a device connected to each other thru one of the 3 serial ports? For example, on a BACNet network, how does one initiate data transfer between 2 devices connected by serial cables.  Is this done thru software, or can be done thru commands inside a command line prompt? How do we do this in Ubuntu and Windows OS?


texts: Combining of two or more ultra low voltage DC/DC step up converter chip's (LTC3108) output

texts: I want to use one LTC3108 with micro solar panel and other LTC3108 with TEG panel. Can I connect two LTC3108s' output to the one battery charger chip's input (max1555 for example)?


texts:
There are two standards for DB9 pinouts when it comes to CAN bus.
This seems to be the industrial version. I've seen it in PLCs and VFDs.

7 - CAN-H
2 - CAN-L
3 - GND
6 - GND
9 - VBAT

This seems to be automotive. The only place I have seen it is in OBD2 to DB9 cables.

3 - CAN-H
5 - CAN-L
1 - GND
2 - GND
9 - VBAT

Where do these standards come from, particularly the automotive one? Looking at the CAN Arduino shield from seed studio and spark fun they have both pinouts and solder jumpers to switch between them.


texts: Can I power my 5.7 V DC synth with a 9 V power bank?

texts:
I own a Roland JD-Xi synthesizer which is powered by an AC/DC adapter. The output voltage of the adapter is 5.7 V DC.

In an attempt to make things more mobile, some years back I made a cable that I could plugin into a 5 V power bank and my synth. It kind of worked but I got problems with some of the analog sounds on the unit, and most likely it is because of the missing volts, so to speak. I kind of ditched that project but now I have got to think about it again. One idea I have is to buy a 9 V power bank instead. I understand that some electronics support quite a wide range of volts.

So, I guess my question is: would it be unresonable to think that my synth actually could accept 9 V input although its power adapter outputs 5.7 V? If you think 9 V is too much/too high, could I make some little tweak to get it down a few volts?

If you are interested in the background, you can read about my project here:

http://muublog.blogspot.se/2016/01/making-jd-xi-mobile-by-replacing-ac.html

Thanks!

/Mathias


texts: VHDL: Constraining Record with another record

texts:
Let's assume I have a type of record containing unconstrained elements:
  type Axi4s_M2S is record
    Tvalid : std_logic;
    Tdata  : std_logic_vector;
    Tstrb  : std_logic_vector;
    Tkeep  : std_logic_vector;
    Tlast  : std_logic;
    Tid    : std_logic_vector;
    Tdest  : std_logic_vector;
    Tuser  : std_logic_vector;
  end record Axi4s_M2S;

Now I implement two signals. "A" is completely constrained. The other one should be constrained using the first one.
signal A: Axi4s_M2S(Tdata(7 downto 0)......);
signal B: Axi4s_M2S(--constrain me likewise A);

Is there a way to do so?


texts: Emitter-base voltage in ideal-diode circuit for voltages >5V

texts:
I stumbled over the circuit in the related question which accroding to the explanation and my understanding implements a comparator by means of two PNP transistors to pull the gate of the P-channels MOSFET.

I would like adapt the circuit select between multiple voltages sources of in the range of 4.5V - 24V like this:

simulate this circuit – Schematic created using CircuitLab

My issue is that is seems that when the input voltages differ largely like 5V at input 1 and 24V at input 2, the emitter-base voltage of Q2 becomes quite large, exceeding the maximum rating of the BJT. Is this understanding correct?


texts: Can I use opamp to convert 5V DC into 10V DC?

texts:
Can I use an opamp as given below to convert 5V to 10V DC?

If yes then why do we go for BOOST converters?

If both methods are suitable then which is better method and why?


texts: Arduino Blink example does not run after upload from eclipse

texts:
I just started with my first Arduino project. I am trying out the Blink example. I have set up eclipse for arduino 1.0 and the code compiles without errors (both lib project and blink project).
I used the tutorial at: http://arduino.cc/playground/Code/Eclipse
When I upload the code to the board using the upload button avrdude says successful upload but the code never runs. I am using an unmodified blink code supplied with an additional main() to sequence the init, setup and loop.

What am I missing? Can someone help me out?

Edit:
Here is the code I am trying to run. It is the eclipse blink project linked at the end of the tutorial above. Link: https://github.com/ricovangenugten/Arduino-Blink-Eclipse-Project/tree/master/Blink


texts: Does this use of IR2183 as high-side n-channel gate driver work?

texts:
I'm building a switching power supply taking 12V to 19V at 3A max out. I've already built one of these using a Schottky diode for the rectifier, but this time I'm thinking of trying a high-side-switched N-channel as the rectifier to reduce losses. The end result is to power a small computer based on a battery input (range 9.9V -> 16.8V, 3S or 4S LiPo.)

The battery circuit is separately fused/switched; this is the boost power supply part only.

My question is: The MOSFET driver IR2183 has a "typical circuit" that ties the VS signal for the bootstrap capacitor to the load in a different way than I'm doing here. Specifically, it shows the load as connected between the source and drain of the two MOSFETs, whereas I tie them together to provide a single output. Will the 2183 still properly bootstrap the gate drive of Q4? My guess is "yes" but I'd like a double-check by someone who's ideally done this before :-)

IR2183 datasheet
MC34063 datasheet


texts: How does an op amp's bandwidth affect its rise time with a step input?

texts: Can't seem to find the connection between the two. I have an error amplifier being fed with an analog signal. I'm varying the GBW of the op-amp to determine how does its GBW affect the rise time of the output. From my spice simulations, what i'm only getting is that increasing the bandwidth reduces the low and high frequency voltage ripples of the output. A higher bandwidth seems to give a faster rise time but I don't understand why is that so.


texts:
This is what I understand about the circuit:

It's not a window comparator exactly as the outputs are not connected together and the inverting inputs are actually connected together. They look like two Schmitt triggers.
Resistors R15 and R16 are pull up resistors as the comparators outputs are open collector.
R8, R9, and R10 form a resistor divider network to set the voltage references. According to my calculations, I get 10.2V for V1 and 6.46V for V2.

Correct me if I said something wrong.

What I don't understand:

What's the purpose of the diodes in the positive feedback?

EDIT:

R11 = R12 = 200k

R13 = 332k

R14 = 237k

I found this question that gave me a better insight on why the diode on the feedback path:

Diode in positive feedback?


texts: Using LCD module with poor / missing datasheet

texts:
I've got an NMTB-F000393FGHSAY-A 2-row character LCD display module, which I'd like to use in a project. It's got 18 pins in a 2x9 configuration on the back. I pulled it out of an existing (broken) product, so there's no additional information with it.

Some searching shows that it was manufactured by Microtips Technology, and hints that it might be a custom design for a particular customer, but unfortunately I can't find any datasheets for the device, or even devices of the same series.

Any idea how I can find more information on this device? Anyone have any guesses as to what kind of interface or protocol it might use? I can provide a picture of it if necessary, but I don't have a good enough camera with me right now.


texts: Connecting components to an arduino without a breadboard

texts:
I've never worked with an arduino before, so bear with me.

I'm looking to start a project with an arduino nano, and I want to keep everything as small and as light as possible. Because of this, I want to avoid using a breadboard. Ideally I want to wire the arduino directly to the components. How would I go about doing this? For example, lets say I want to connect a PIR motion sensor to the nano. What kind of wire will connect the arduino pins to the holes in this component? Sorry if this is an obvious question. The images of the PIR components and the nano are below.

edit: Also I'm hoping to avoid soldering just because I might want to re-use either of the components.


texts: Ultrasonic sensor(ping) and deep sleep Arduino

texts: Is it possible to use an ultrasonic sensor to wake up an Arduino which is in deep sleep when an object is detected within a few cm and then do stuff?


texts:
What are Boolean matrices? How can one represent Digital Circuits using them?Please see if the
following link helps?
http://comjnl.oxfordjournals.org/content/15/3/247.full.pdf


texts: What mechanism happens inside an inductor from the point when potential difference is applied?

texts: What happens when a potential difference is applied across an inductor? I am trying to get a picture of mechanism from start, just after potential difference is applied in detail? In resistor we can see that there are positive ions opposing and current flows at constant rate so energy dissipated in resistor is equal to that given by battery. But what is happening in conductor so that the induced EMF gets equal to E? What is the picture of the mechanism?


texts: Can I use diodes to protect power supply outputs?

texts:
(Note, this is my first question on this site, please point out if there is something that I am doing wrong here.)

I have a thyratron that requires two separate power lines to attach to it. The two power lines meet at a single terminal on the thyratron tube.

One of the lines is a -100 volt DC and 100 milli-amp bias.

The other line is a series of 200 V pulses that are sent out at a frequency of 10 hertz. The pulses last for 0.4 micro seconds and have a rise and fall time of 1.5 kV/uS (the 200 V needs to be reached in 7.5 uS or less). Please also note that the pulses are only positive, so there are just 10 of these every second.

Since the pulses would probably mess up the DC bias, it seems reasonable that I would put a capacitor between the terminal and the pulse source and an inductor between the DC source and the terminal.

My question is, how should I calculate the capacitance and inductance that will be needed?

Also, could I just use a diode to protect the DC and pulse source?

Here is link to the basics of a thyratron: https://en.wikipedia.org/wiki/Thyratron

simulate this circuit – Schematic created using CircuitLab


texts: Difference between single circuit and double circuit transmission line protection systems

texts:
I'm doing a research on long three phase transmission line protection systems and I found many schemes such as distance protection, merz-price voltage balance system, split-conductor, "translay" protection system, etc.

However, I am not sure protection systems are specific for the number of circuits per transmission lines, that is some circuits work only on single circuit lines other work only double circuit lines.

If there's a difference between the two types of protection systems, is it simply a question of installation, meaning that a protection system is installed on each circuit independently? Or do double circuit transmission lines have their own protection systems?

Thank you!


texts: ATX power supply doesn't turn off after PS_ON wire is disconnected from GND

texts:
I'm using an old ATX power supply to power a PlayStation 3. I've built a small circuit to make the power supply only fully turn on when the PS3 is turned on, by using an optocoupler that connects the PS_ON wire to GND. The thing is that it works only to turn the power supply on, when I turn the PS3 off the power supply keeps working. Even if I disconnect the PS_ON wire from the circuit and hold it in the air, it won't turn off, only does so if I connect the PS_ON wire to 5V.
Now I must say that I desoldered all the wires coming from the power supply except for a 12V wire, a GND wire, the PS_ON wire and the 5VSB wire. I don't know if this could be the reason behind the problem. Here is a pic:


texts:
I was Going through some application notes for the placement of Series termination of DDR and found it should be placed near to the processor.

But if I am not wrong termination resistor are placed to match the line impedance so there will not be reflection back from the Receiver. So why not to place series termination near to DDR memory (Receiver side), since in the case of series termination place near the Processor the reflection of signals travels from DDR Memory (Receiver) to Processor (Transmitter)?


texts: How to measure a BC-547 transistor's details?

texts:
I am new in electronics.

What I am trying to do is measuring everything of BC-547 transistor's details from a basic circuit design practically. I want to measure as example: collector-emitter voltage, emitter-ground voltage, base-ground voltage, base-emitter voltage etc.

This is the diagram. I connected everything correctly.I got it in my text book. I used as base resistor 1 mega ohm and collector resistor 1 kilo ohm.

Now, I can not understand how to measure them practically by multimeter (instead of theoretical formula). Any help please ?


texts: Right way of wiring discrete LEDs to make a high power LED panel

texts:
I want to make an LED panel as shown below:

I need some help understanding the wiring of discrete LEDs. Typically discrete LEDs are rated for 185 mA at 2.7 V. Calculated wattage will be roughly 0.5 watts.
I want to make a 100 W panel which means 200 LEDs. I understand that LEDs should be driven by a constant current source but it will be highly impractical to put the entire set of LEDs in series and drive using a CC power supply. The voltage requirement will be roughly 540 V.
The second option is to connect the LEDs in a series-parallel network that looks like this:

8 LEDs in series and 15 such series networks in parallel. In an ideal case, this setup can be powered up by a constant current source of 4.625 amps (assuming equal current distribution in the parallel networks). I guess they use a very similar circuit in the chip on board LED lights (shown below):

My questions are as follows:

Can I just connect a 4.625 amp constant current source on red and black wires and expect the setup to work correctly?

Should I regulate the current in the individual series group network to 185 mA and feed the whole setup with a constant voltage power supply?

How do COB lights distribute the current so uniformly that they do not need current regulation in individual series group?


texts:
Which type of connector is it?

DC, 4 pins, a plug (cable side, not board side) with 4 female sockets.
It resembles a Kycon 4-pin DC connector but reversed.

It is taken from FSP's AC/DC adapters and can also be found in several laptops.


texts: Best temperature storage IC? EEPROM or SRAM IC

texts: I am trying to integrate a temperature sensor along with the storage capability with it. Both temperature sensor and the storage device will be controlled by FPGA. Which device would be the most appropriate way to choose as storage device. EEPROM or SRAM IC or any other?


texts: Using MOSFET to turn on/off a sensor controlled by ESP8266

texts:
I want to power an MCU (ESP8266, 3.3V) and an ultrasonic sensor (HC-SR04, requires >= 3.7V) using AA batteries.
By using an efficient LDO (MCP1700T-3302E) and spending much time in deep sleep mode, the average current draw of the MCU itself stays below 0.1 mA. However, since the ultrasonic sensor seems to draw a (relatively high) quiescent current of around 1.5mA, I'd like to control it's
VCC line by the ESP and turn it on only when needed. Doing this in a power efficient way seems to be
done best using a MOSFET, maybe like in the following schematic?

simulate this circuit – Schematic created using CircuitLab

Does this plan make sense, what model would be optimal for M1 (especially considering the battery/low power
context) and does the gate require an additional pull-down or series resistor?


texts: Current capacity of copper wires in vacuum

texts:
I’d like to know the current carrying capacity of copper wires in vacuum.
The current plan (NPI) calls for sending ~3 amps through the vacuum space of a cryostat.
Has anyone done this?  Have any references, links, or sage words of advice.
I found this,

http://snebulos.mit.edu/projects/reference/International-Space-Station/TM102179.pdf

and  a few other references. (Kurt J. Lesker gives single numbers.) The slope of those curves in vacuum is about 2.  Which at least makes some physics sense.  Heat generated goes as I^2 and heat dissipated goes as T^4 (Assuming all the heat dissipation is by radiation… Stefan- Boltzmann  law.)

Oh one kinda crazy idea would be to put a thick layer of heat shrink tubing over the wire.  Better emmisivity and a larger area.  (Perhaps something other than heat shrink.)


texts:
Suppose we have a 400 kHz I2C bus. There is one master and a bunch of slave devices.  We would like to introduce one more slave device, but unfortunately it only goes to 100 kHz .

Clearly, the solid design choices are:

just run that bus at 100 kHz
use separate buses for the 400 kHz and 100 kHz peripherals

But the question is just about a hack: what if we use one bus, and address the 400 kHz devices at 400 kHz, and switch the bus to 100 kHz when speaking to the 100 kHz slave?

Or could the slower slave misbehave in response to the 400 kHz hash that it sees on the I2C lines because it mistakenly thinks that it is being addressed?

Can we depend on 100 kHz devices to still be able to process 400 kHz I2C signal sufficiently well to reliably ignore messages addressed toward other slaves?


texts:
The circuit in the figure below is a circuit for measuring frequencies for RKE systems (a key fob, for example). The frequencies for which this circuit was created, was used to measure frequencies between 100MHz and 500MHz. The values of capacitors and inductors in the schematics are not very accurate because I did not measure these components out of the board yet. However, the doubt I have about this circuit is much more qualitative than quantitative, I still haven't fully understood its functionality.

As far as I can understand so far, the antenna, which in this case is nothing more than a loop made of very thick conductive wire, feeds a prescaler, the MC12080, which divides the frequency received from the entena by 20. The output of the prescaler passes by an amplification step to be able to feed a binary ripple counter, MC74HC4040A, which in turn loads an 8-Stage Static Shift Register, CD4021BC.This circuit, as described above, has the effect of dividing the original frequency by 20, then by 256, that is, it divides the original RF frequency by 5120.

I imagine that, when the microcontroller sets the input level of transistor Q2 to low for a short period of time, it counts the number of pulses at the output of the shift-register and, this way, calculates the frequency of the signal received by the antenna.

However, I have the following doubts:

1) In the circuit, after the prescaler, there are two branches, and in the lower branch in the schematic, there is a transistor Q2 that I do not know the reason for its existence. There is a capacitor and a resistor in parallel in the collector of this transistor that I don't know what they are for. The colector of the transistor Q2 is connected to the microcontroller, but I don't know why this is made.

2) I intend to use this circuit to perform frequency measurement in the 300MHz-500MHz and 800MHZ-1GHz bands. In fact, I'm interested in frequencies of 315MHz, 433MHz, 868MHz and 915MHz, but I have doubts whether the antenna currently used to measure frequencies between 100MHz and 500MHz will, under higher frequencies, provide enough voltage values for the prescaler. So, I imagined to put a second antenna, which I would choose by switching a relay. What do you think about this ? Can I do this with an antenna as simple as a single conductive loop like the one currently being used?


texts:
I don't know if this is the right place to ask so please tell me.

I am puzzled by devices like "nvidia jetson tegra" or "Snapdragon 835 Mobile Hardware Development Kit" and many many others.
What exactly are those devices? Where do people use them? and Who uses them?

I know that raspberry PI is a single board computer and that people use it just for fun to develop some fun apps but the problem with those other devices is that they big not like Pi.
Do people use those devices for personal use?


texts: How to protect each cell connected in parallel in a Li-ion battery pack

texts:
I am making a 1S2P Li-ion battery pack. One of the requirement is I need to protect over-charge and over-discharge by detecting the voltage of each cell. The protection circuit/IC should interrupt the battery when any one of the cells is over or under voltage.

I find most of the protection IC is to protect the cells connected in series, such as LV51131T. When connecting the cells in parallel, the way I can think of is to add multiple protection IC, such as DW01-P. Each protection IC connects to a single cell and adding diode on each branch. Therefore there will be two identical protection IC on the board.

However, by searching from the web, it seems nobody is using this method. I would like to ask what is the normal or correct practice for this purpose?

Thank you very much


texts: Will a multi-stage charger pollute the output from a 12V battery?

texts:
I would like to hook up a computer to a 12V battery, and I need a clean 12V input to the computer because only buck regulators will be used to deliver the outputs to the computer, no sinusoidal waves.
The fly in the ointment is that the battery(ies) need to be constantly charged. If I charge them using a typical high power multi-stage charger (sometimes called "smart" chargers), will the charger pollute the DC output from the battery(ies) with sinusoidal waves that would be bad for the computer?
If indeed the charger will pollute the output of the battery(ies) if it is directly connected to them, I can see two possible solutions to this problem. One would be to install some GIGANTIC capacitors between the battery(ies) and the charger to rectify the charging input to the batteries. The other would be to use relays and a double stack of batteries. In other words, I would have not one, but two power reservoirs. The computer(s) would run off of one of the reservoirs, while the other was being charged. Then it would reverse. The computers would switch to the second reservoir and the charger would simultaneously switch to the first reservoir. Would either of these strategies work?


texts:
I am using Xilinx's CoolRunner-II series CPLD, and programming programmable logic for the first time.

I have to use few of flip-flops with asynchronous reset.

I wonder what is the difference between active low and active high reset in terms of implementation?


texts: Media Independent Interface (MII) vs Media Dependent Interface (MDI)

texts:
Is my understanding about Ethernet - MII & MDI correct?

MII - Media Independent Interface is about the connectivity between MAC and PHY. In other words, it is about TXD and RXD signals from MAC to PHY.
MDI - Media Dependent Interface is about the connectivity between PHY and Connector/Jack(RJ45). In other words, it is about TX+/- and RX+/- signals from PHY to RJ45.

Also, I noticed that for 10/100Mbps Ethernet, only 2 differential pairs are needed between PHY transceiver and RJ45 whereas for 10/100/1000Mbps Ethernet, 4 differential pairs are needed between PHY transceiver and RJ45. Is that correct?

It would be really nice if you could post a link to a resource or app note that illustrates the basics of Ethernet connectivity that discusses the concepts above.


texts: Signal rectifier - what is the use of the resistors?

texts:
In the art of electronics book, page 49, 2nd edition, they show a signal rectifier circuit (a circuit that tosses away the negative part of a signal). Here it is:

simulate this circuit – Schematic created using CircuitLab

I think the capacitor is there to block out DC. Is that right?
What are the uses of the two resistors? Couldn't the same goal be accomplished by taking them out?

I think R2 between GND and the diode is needed for the diode to work correctly, as a way for the circuit to drop the needed voltage so the voltage drop across the diode stays at the diode forward voltage drop.

What about R1?

Thank you very much.


texts:
Hi I've done some dev using AVR's.

I'd really like to use the arduino but continue using atmel tools.

Is this straightforward?

Is there a converter that I can use my 910 programmer with? I think it's a 10 pin connector


texts:
I use a Boarduino and a 30-row bread board to program my ATtiny.  I load a not too complicated sketch called ArduinoISP (included by default now in the Arduino IDE), and suddenly I have a working programmer.  Atmel sells a nice programmer for between $30 and $40, and there are lots of kits for making cheaper ones.

I was very happy once I got my working programmer and made the tiny blink some leds.  However, now my poor boarduino is stuck on programmer duty.

As far as I can tell this programmer holds down the reset button, and then transmits and receives on the MOSI and MISO pins.  I think the SCK is unused or at least unneeded. (SCK is needed according to the ATtiny datasheet, my programmer doesn't work without it, and I can't find the place I thought I read it was not needed.)

Why do I need a hardware programmer to just transmit serial? I mean, let's suppose I am willing to hold down the reset button with my finger instead of using an IC.  All that's left is serial send and receive, so all I need are three wires GND, RXD, and TXD.  Heck, if I have the "DTR" line or whatever, you can even hold down the reset button with the serial cable.

  Why are there all these hardware solutions that also require fancy software (like AVRdude, or AVR studio, or whatever)?

I mean I could understand a little USB cable that presented the microcontroller as a mass storage device and let you drag binary files over for programming (like this ARM dev board).  Hardware only, using standard software drivers.

I could also understand a software only solution (modulo hooking wires from the USB to the chip, using something like the FTDI chip to simplify what goes down the wires).  All of the fancy programming protocol would be handled by software on the computer, and the hardware would just be some wires.

Why do we have both (complicated) software and hardware involved?  I mean, as far as I can tell, programming microcontrollers is pretty easy, but when I was just getting into this I was really worried about how I was going to ever buy a chip from mouser or digikey without paying some guru to program a bootloader for me.

I'm sure there is a good reason (it's not like I've written the software or started manufacturing the drag-n-drop USB programmer), but as a newcomer, I have no idea what it is.


texts: What is the name of the current that creates the potential difference in an opamp?

texts: Almost zero current is drawn by an opamp from its inputs (in theory), but still there must be tiny current causing the opamp to feel the voltage. What is the name of that sort of current in electrical engineering terminology?


texts:
I have a two transformer, one is 5A and the other one is 3A. It is different brand. The output voltage is same 12V.

My question is, can I combine them together so I can get 12V 8A?

Should I combine them after the diode and then use one capacitor or should I give each of them capacitor and then combine after it?

Thanks.


texts: Running GSM module from primary batteries (ER34615)

texts:
I'm designing a small telemetry system that will take measurements every few hours and send the data through 3G at the end of the day. The target battery life is 1 year.

The GSM modules is an XBee 3G. The module draws about 700mA at 3.3V when transmitting. That is the averaged current, I don't know how is current waveform composed.

My first idea was to use 4 AA alkaline batteries and two 50F supercapacitors with a current limited charging circuit, so I won't draw more than 150mA from the batteries and allow the GSM modules to run just from the energy stored in the supercapacitors. The problem with this is the cost of the supercapacitors and circuit, the large space it ocuppies and the time is takes to load the caps (about half an hour if I'm not wrong).
My second idea was to use 4 AA Energizer Lithium batteries. This batteries allow me to draw up to 1A without significant capacity reduction and they are well known so you can buy them almost everywhere.
My third idea was to use a ER34615 battery. The energy density is really good and I could easily achieve more than one year of battery life. The problem is they are also rated for currents up to around 300mA which is very low. I have seen some brands like Ultralife which offers this ER34615 with currents up to 2A which is perfect for me but they seem to be rare and I can't find them in my country.

I really like the idea to use a ER34615 cell. Is there any way I could use it without destroying the battery capacity due to the large currents? I though about using a smaller supercapacitor in parallel with the battery but if the average current is 700mA there's not much a parallel capacitor can do. How are GSM modules usually powered in this applications where battery current capability is so limited?

EDIT 1:

Ok, to properly test the current drawn from the XBee 3G I connected to a 3G network and covered the antenna in aluminium foil and powered the module with 3.5V to get a -90dBm signal strength.

I sent 1000 of data (plus HTTP header overhead) with a POST request to an echo server, so I receive 1000 bytes (plus HTTP header overhead) of data back.

During the data transfer the current was around 320mA, no big current spikes as in 2G connections. The 320mA were pretty much constant during a few seconds, after that, the module sits in idle at around 80mA also with no current spikes. I don't really know what to think, because Digi has this power consumption table:

I don't have a way to know the transmission power but having such a low signal level and being at 320mA makes me think how they measured those 700mA.

EDIT 2:

I dropped the voltage to the absolute minimum of 3V and covered the antenna even more so I get -95dBm now. The current stays about the same but only sometimes the current goes to about 800mA during the transmission (a seconds or less). So this 700mA advertised by Digi seems to be the worst case scenario. With relatively good signal levels it's hard to go above 400mA, at least in my network conditions.

The ER34615 are rated for 300mA maximum while dropping the capacity to 9Ah, although this is rated at a continuous 300mA during the battery lifespan. In worst cases a 800mA current drawn from the battery for a about a second can lead to significant voltage drops unless I add some beefy capacitor? Is it possible to calculate how much energy I would be wasting from the battery due to the internal resistance when draining say 800mA during a second?

I think the Energizer Lithium may end up being a better choice because as the ER34615 discharges I may be using more than 300mA due to the boost converter and this will reduce even more the battery lifespan.


texts: schematic symbol from power supply, two triangles pointing together

texts:
What does the symbol marked Z1 (two triangles pointing towards line) represent in this schematic?:

This is coming from the reference design on page 10 of the LD7550-B pulse width modulator datasheet (Jan 2005 version). You can get the datasheet here.  It's not written in the datasheet anywhere I can see, and in the table of part numbers the component value is written as "N/A".


texts: Help for analog signal chain for 16bits ADC

texts:
I work on analog amplifier and filter chain for an internal STM32H753VI 16bits ADC. The signal chain is based on ultra-low noise opamp LT6237 and differential driver LT1994. The sample-rate of ADC will be 96 kHz. I cascade opamp to create amplifier stage and sallen & key cells trying to minimize noise spectral density and keep output signal offset very low (I don't have power consumption limit here.) I try my best but I got problem with Low-pass frequency response, I don't know if my output can be connected directly to the ADC and I wonder if I do big mistake and how I can optimize the noise spectral density.
SCHEMATIC & FREQUENCY RESPONSE

1. LOW-PASS PROBLEM : WHY THIS STRANGE BEHAVIOR ?
The response of the whole chain got a strange behavior @1MH it come from the sallen & key low-pass filter. I don't where the increase of gain came at 1 MHz and I don't know how to correct this.
Can you help me to solve this problem ?

2. ADC ELECTRICAL COMPATIBILITY : CAN I CONNECT MY ADC "AS IS" ?
I don't know if I can connect directly STM32H753VI 16bits ADC to OUT+, OUT- and GND(AVSS).
I just put antialias filter a 37kHz but I don't know if ADC and LT1994 impedance are compatible.
Can you help me to adjust my output to the ADC input ?
Here are the electrical caracteristics of the ADC

3. LOOK LIKE "NOT TOO BAD" SIGNAL CHAIN OR NOT ?
Do you see big mistake or misconception at first view on my chain ?
Do I miss basic rules in analog chain design ?
4. NOISE SPECTRAL DENSITY OPTIMIZATION : CAN I OPTIMIZE ?
I try my best to achieve lower noise density but I am not very good in analog world.
Do you think it's possible to lower the noise density ?
In other word, do you think I can build this analog signal chain (notwithstanding opamp power supply decoupling capacitor, LDO and ultra-low noise voltage reference chip, etc..) with average chance of working ?
Thanks in advance for your help to understand what I do, but analog world is not simple and with time I lost all what I learn...


texts:
Is it possible to create a circuit with three resistors that can be changed from series connection to parallel connection with a switch?

Can this be done simply enough to reproduce in a simple simulator like http://www.falstad.com/circuit/ ?


texts: Nema 17 stepper motor(ks42sth34-1504a) not working

texts: I am trying to connect a new Nema 17 stepper motor, ks42sth34-1504a, using TB6600.  It is a 6 wire stepper.  While measuring resistance for identifying coils, only one pair(1 and 3) shows any resistance, around 2.0.  All other combinations show no resistance.  I tried connecting the motor to TB6600 pairing 1-3 and 4-6 that makes the motor flutter.  Is this a broken motor? Please help.  Thanks in advance.


texts: I was able to find a Monolithic Li-Ion battery charger on line to study how battery charging circuits work (see the image attached).If this circuit is correct, then there is a shut off circuit that will detect a fully charged battery and shut off any previous circuit. The previous circuit is an DC-to-AC (electric energy from solar panel is converted to AC) converter, transformer, and an AC-to-DC converter which I did not include. However, the output of this conversion system was 12 volts, which I represented by the 12 V voltage source to make things simple. However, I do not know what component of the circuit I found does just that. Can anyone please let me know where it is?


texts:
I want to build a 0 - 24V dual( + & - ) regulated power supply. My problem is that I am not sure which transformer to use. The purpose of the power supply is as lab power-supply.

I intend on using the LM317 and LM337 as regulators with all necessary filters and such. Just not sure about the transformer. The Primary Voltage is 230V @ 50 Hz.

Any suggestions?

Edit: Schematic


texts: Two wire vs. three wire serial interface for RTC

texts:
I'm looking to choose an RTC for a project I have in mind.

I have the following options (linked to datasheet):

DS1307
DS1302

The main difference seems to be the communication protocol. The DS1307 seems to use something called "two-wire serial interface" whereas the DS1302 uses something called the "3-wire interface".

I would like to use one of these chips to keep time on my ATMega microcontroller (probably ATmega8).

So how are these two different, and how would I hook them up?


texts:
I am trying to advance my coding skills and venture into the world of high-end microcontrollers, coming mainly from a Java background (1 year of android developer as a daytime job plus a bit of C developing around Attiny in Atmel Studio) I fell in love with the abstraction provided by STM's HAL. I am aware that this is a sub-optimal solution from an optimization point of view but decided to go down this way because of how promisingly fast it looks.

I started from the very basics, turning on a LED but, after an evening of no luck I really need some help.

Here is my code, it is compiling fine, uploading fine but... nothing happens!

I'm using an STM32F4-Discovery board.

#include "stm32f4xx.h"
#include "stm32f4_discovery.h"

GPIO_InitTypeDef GPIO_InitStructure;

int main(void)
{

HAL_Init();

__GPIOD_CLK_ENABLE();
GPIO_InitStructure.Pin   = GPIO_PIN_15;
GPIO_InitStructure.Mode  = GPIO_MODE_OUTPUT_PP;
GPIO_InitStructure.Pull  = GPIO_PULLUP;
GPIO_InitStructure.Speed = GPIO_SPEED_HIGH;
HAL_GPIO_Init(GPIOD, &GPIO_InitStructure);

while (1) {

        HAL_GPIO_WritePin(GPIOD, GPIO_PIN_15, GPIO_PIN_SET);
    }
}


texts: Charging li-ion batteries with protection circuit

texts:
If i'm using a protection circuit like this one:

http://www.batteryspace.com/pcbfor148vli-ionbatterypack5alimitwithfuelguagesocket.aspx

and 4, 3.7v li-ion batteries.

Can I use a simple 16.8v dc wall wart to charge them?

or do I still need a special li-ion battery charger, and if so what is the purpose of the circuit?


texts:
I am storing a 16k constant sine table of 14 bit signed vectors in a package.

I use this package in my module to read out the array in a clocked process

But I get this warning during synthesis and my synthesis is taking a long time -

  The RAM  will be implemented on LUTs either because you have described an asynchronous read or because of currently unsupported block RAM features. If you have described an asynchronous read, making it synchronous would allow you to take advantage of available block RAM resources, for optimized device usage and improved timings. Please refer to your documentation for coding guidelines."

code in package -

TYPE signed_array IS ARRAY (integer RANGE <>) OF signed (DATAWIDTH-1 DOWNTO 0);

CONSTANT SINE_TABLE_SIZE : integer := QUARTER_LENGTH+1; -- 16384+1
----sine pi/2 = 1 <=> "0111111....1" MSB is 0 because of the signed representation

CONSTANT SINE_TABLE : signed_array(0 TO SINE_TABLE_SIZE-1):= (
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.0), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*9.5873799096e-05), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.000191747597311), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.000287621393763), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.000383495187571), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.000479368977855), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.000575242763732), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.000671116544322), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.000766990318743), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.000862864086114), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.000958737845553), DATAWIDTH) ,
                    to_signed(integer((2.0**(DATAWIDTH-1)-1.0)*0.00105461159618), DATAWIDTH) ,

process(clk)
    if rising_edge(clk) then
        ctd <= ctr + 1;
    end if;
end process;

cos <= SINE_TABLE(to_integer(unsigned(ctr)));

Any suggestions on how to write a vhdl code in infer a block RAM instead of LUTs?

The SINE TABLE is in a package, and the process is in the main module


texts: How to convert this ASM diagram to register transfer level?

texts:
So we have this ASM diagram, which I have to convert into register transfer level.

I have already done some similar examples and I will usually start with defining next-state logic, than output logic and register data path.

With this example I have trouble with defining next-state logic. If I make table of state transitions, I need to take also start, a and b in consideration. Since we have 4 states we need 4 bits for that + one bit for start, one for b!=0 and one for a > b. That is simply too much combinations to write on paper. I suppose that maybe there is simpler solution for this.

What does the ready A state do? I'm confused from the diagram.


texts: Voltage regulator bypass capacitor placement

texts:
At both the input and output (especially the output), I need to place several bypass capacitors (all MLCC).  The datasheet for the voltage regulator seems to suggest that using a 10uF on both the input and output is usually adequate.  However, I see some high frequency noise (switching regulator) that I'd like to supress as well.  To address this, the app note suggests using additional smaller value capacitors targeting those frequencies (based on the resonant frequency of the MLCC capacitor).

I'm using multiple capacitors at varying values, such as  0.001uF, 0.1 uF, 10 uF.  Where should I place these three capacitors in relation to the voltage regulator chip?

Should I place the biggest capacitor nearest to the IC or the smallest?


texts:
I want to repair the circuit of a Mixer that used the TS820 thyristor.
The other components were healthy except the thyristor so I replaced the TS820 with the BT151 but the circuit did not work.
Now I have two questions

Can I start the circuit with a BT151 thyristor by changing the resistors or capacitors in the circuit?
Can I use MCR100 or C106 thyristors because I can not find the TS820 thyristor?


texts: How do you do superposition to find value of voltage source

texts: I know when you are using superposition you have to find the contribution of each independent source. You do this by turning voltage sources to short circuit and current sources to open circuit. then you sum the value of the contributions. This question asks for the voltage of a independent voltage source, would i just consider the contribution of the current source then?


texts: What are some good options for high speed light detection (less response time along with sensitivity)?

texts: I wanted to implement a one way wireless optical communication using arduino and LEDs but soon I had to choose sensors. LDRs are very slow and IR does not respond to visible light. My aim is to achieve 3-4 m of transmission so a sensitive sensor will be better for implementation.


texts: Is there a development system for the MSP430F series microcontrollers?

texts: I'm hoping for an IDE of some kind, but I'll take any compiler or assembler! Can't seem to find anything by googling.


texts: How to choose a flyback diode for a relay?

texts:
A diode is put in parallel with a relay coil (with opposite polarity) to prevent damage to other components when the relay is turned off.

Here's an example schematic I found online:

I'm planning on using a relay with a coil voltage of 5V and contact rating of 10A.

How do I determine the required specifications for the diode, such as voltage, current, and switching time?


texts:
I've got some really tiny leads on a USB port that I need to solder to a board.

The local Hackerspace has a microscope that I'm going to see about using this for, but even a soldering iron is gigantic compared to these tiny leads.  Does anyone have any tips (pun intended and unintended) for soldering these leads to a board?


texts: Compromising on placement or routing of decoupling cap with BGA package

texts:
As far I know there are two important points related to power-supply decoupling capacitors. First the placement be less than 3 cm from the digital IC. Second the power tracks route pass through this capacitor first and then connect with the digital IC power pins or balls.

If I have problem in fulfilling both requirements especially in the case of BGA package then where can I do some compromise, in its placement or in its power-trace routing so that it causes lesser harm to the operation?


texts:
I'm using Raspberry pi 3 and V2 camera.
I want to control the 4 cameras.
Two cameras are working but the other two are not.
It is a picture of two deferential pair signals compared using an oscilloscope.
What causes does a voltage difference in a deferential signal grow?

Photo 1: Normal operation.

Photo 2: Abnormal operation.


texts: How to activate one LED separately in a group of LEDs?

texts:
I want to activate one LED in a group of LEDs depending resistance varies linearly depending on the temperature.
I am using variable resistance that Controls how LEDs will light.
LED1 and LED 2 and LED 3 Depends on Variable resistivity
The problem I have encountered with my circuit, all LEDs turn on at the same time.
Maybe the solution is to use the transistors, but I have no information about which type to use them.
Can somebody help?
[


texts: RL circuit Step-Response Equation explaination

texts:
Im having difficulty understanding the integral calculation in number 4. How does (Response) section of "V/L" convert into "V/R"? Where does exponents go?

The last equation is from the textbook.

*I wanted to show the each steps more clearly so I took a picture of the each step.


texts: Using a "noise eating" active low-pass filter

texts:
I'm trying to use a MAX281 low-pass IC to filter a DC signal I'm producing on-board. I'm yet to find other chips with the same features so, if you haven't come across them, they're designed to work by writing feedback onto your signal through a capacitor. The reason I was attracted to them is that they a) eliminate DC offset errors normally associated with an active design and b) allow me to work with high (150V) DC voltages.

My circuit copies the diagram below, taken from the device datasheet:

The idea is that pin 7 samples the signal via an internal switched capacitor network (hence the clock) and the device writes feedback onto the signal through the capacitor on pin 1.
The only difference in my design is that I don't use an external clock, I instead put a capacitor on pin 5 to use the internal oscillator instead.

However, instead of a filtered output, I find that the chip oscillates. The osc. trace below shows the "DC output" which should be filtered. The other, square-like trace is the output on pin 1 which, when put through the capacitor, causes the shape you see on the output. The clock rate is visible as the little steps in the output level.

Anyone have any tips / experience with these devices / useful google search terms? A rather basic block diagram of the devices is reproduced below:

A link to the datasheet: https://datasheets.maximintegrated.com/en/ds/MAX281.pdf


texts: How can I measure CR2032 RTC battery voltage in a microprocessor system?

texts:
I need a reliable low battery early warning system.
I'm using Epson RX8900SA RTC and CR2032 battery. I want to measure battery voltage (probably every 24 hour or more).
How can I do this without draining battery too much?
My first idea is to use low cost J-FET input amplifier as buffer (voltage follower circuit) and feed microcontroller ADC from its output. If this is good idea - which op-amp can I use? TL082 has too high supply requirements for me (I have 3.3V and 5V supplies avaliable, and TL082 needs at least 6V to do anything). Or maybe I can just use regular low cost single supply op-amp like LM358?
I also want to use some mosfet to connect resistor as load (around 10-20kOhm) at the moment of measurement to make measurements more reliable. Maybe I could just connect 10k-20k resistor directly to ADC and connect that (on high side) by mosfet when I take measurement?
My question is totally diffrent from this.
I'm not asking about ohms law. I asked for solution or some improvement/comment for my idea with high impedance measurement with op-amp or mosfet switch.
Come on guys...


texts: How powerful(in terms of output watts)can current Gunn diodes get?

texts: That is, if I wanted a Gunn diode in the low GHz range with a 20kW output does such a device exist? If not what kind of semiconductor materials would be needed to support ballistic transport at high voltages?