texts: Arduino's "Upload Using Programmer" for ATmega328 (not ATmega328P)

texts:
I am using the the Atmega328 (not the Atmega328P that is standard with Arduino) on a breadboard version of the Arduino.  I am able to get the bootloader on the Atmega328 using these instructions.  In summary, you add a new entry for the 328 to the avrdude.conf file and the boards.txt file.

Then, I am able to get my program on the chip by going to Tools>Board and setting it to  Arduino Uno w/ ATmega328 (non-P) then burning the bootloader on the chip using the 328 config files with the AVR Pocket Programmer.  Then I go to Tools>Board and switch it to Arduino Uno and upload the program using the normal USB connection.

Now, my question is about using the File>Upload Using Programmer functionality.  When I do this for the the Atmega328p on a fresh chip everything works.  However, when I try it for the Atmega328, with the IDE set to upload to Arduino Uno it throws the error:

avrdude: Expected signature for ATMEGA328P is 1E 95 0F
Double check chip, or use -F to override this check.`

Is there another config file that has to be changed to enable the "Upload Using Programmer" functionality on other chips?  If anyone has some tips on where to look it would be greatly appreciated!

Edit1:

I also tried setting the IDE to Arduino Uno w/ ATmega328 (non-P) and it throws this error:

unknown MCU 'atmega328' specified
Known MCU names:
   avr2
   at90s2313
   at90s2323
   at90s2333
   at90s2343
   attiny22
   attiny26
   at90s4414
   at90s4433
   at90s4434
   at90s8515
   at90c8534
   at90s8535
   avr25
   attiny13
   attiny13a
   attiny2313
   attiny24
   attiny44
   attiny84
   attiny25
   attiny45
   attiny85
   attiny261
   attiny461
   attiny861
   attiny43u
   attiny48
   attiny88
   at86rf401
   avr3
   at43usb320
   at43usb355
   at76c711
   avr31
   atmega103
   avr35
   at90usb82
   at90usb162
   attiny167
   avr4
   atmega8
   atmega48
   atmega48p
   atmega88
   atmega88p
   atmega8515
   atmega8535
   atmega8hva
   at90pwm1
   at90pwm2
   at90pwm2b
   at90pwm3
   at90pwm3b
   avr5
   atmega16
   atmega161
   atmega162
   atmega163
   atmega164p
   atmega165
   atmega165p
   atmega168
   atmega168p
   atmega169
   atmega169p
   atmega32
   atmega323
   atmega324p
   atmega325
   atmega325p
   atmega3250
   atmega3250p
   atmega328p
   atmega329
   atmega329p
   atmega3290
   atmega3290p
   atmega406
   atmega64
   atmega640
   atmega644
   atmega644p
   atmega645
   atmega6450
   atmega649
   atmega6490
   atmega16hva
   at90can32
   at90can64
   at90pwm216
   at90pwm316
   atmega32m1
   atmega32c1
   atmega32u4
   atmega32u6
   at90usb646
   at90usb647
   at94k
   avr51
   atmega128
   atmega1280
   atmega1281
   atmega1284p
   at90can128
   at90usb1286
   at90usb1287
   avr6
   atmega2560
   atmega2561
   avrxmega4
   atxmega64a3
   avrxmega5
   atxmega64a1
   avrxmega6
   atxmega128a3
   atxmega256a3
   atxmega256a3b
   avrxmega7
   atxmega128a1
   avr1
   at90s1200
   attiny11
   attiny12
   attiny15
   attiny28
Blink:-1: error: MCU 'atmega328' supported for assembler only

Edit2:  Here is another person with the same problem but without an answer.


texts: Difference between ARJC01-111002T and ARJC01-111002AR RJ45 connectors

texts:
I'm looking at two RJ45 connectors both by Abracon. The  ARJC01-111002T and ARJC01-111002AR. They are both 10/100 Base-Tx Tap Up with LED included. The difference lies in the Magnetics schematic:
The ARJC01-111002T:

The ARJC01-111002AR:

I see there are differences in the magnetics schematic. But I do not understand what is the practical effect of those differences. For what use cases should I use one connector over the other?
Thanks a lot!


texts:
About a week ago I had an idea to build a computer EKG using the computer's mic input as a signal input. One of the most complete tutorials I found on the internet was this one (that is applicable on ECGs also). Here is a view of the circuit:

The first part is an AD602AN amplifier (very common on EKG circuit). All the other op-amps are filters:

-first: 60hz noise cutter

-second: galvanic current (from the skin) cutter

-third:I don't know if it is necessary for an EKG(see link for more info)

-fourth: I think its something related to gain adjustment

-fifth: again, a 60Hz noise cutter

I have some questions:

Is there any useful changes on the circuit given that it was primarily built for an EEG, not ECG?

-In case I want to "skip" some filter in the circuit, can I add a switch that will make the signal pass through the filter or directly to the next filter(alternator) without any kind on loss?

-Any recommendations al all?

Thanks


texts:
I'm shopping for some bulk male header pins and noticed a lot of options for the contact length column. I know 1" is a longer pin than I'm used to and 0.1" is too short, but is there a standard length for these parts, or a fairly standard range of lengths?

I guess for many applications, it's not gonna matter, but when I'm buying a lot of them, they'd better be the right length!

EDIT: breadboards are the main target for these headers.


texts:
Reading this question and its answers (as well as other questions), it seems that in an idealized short-circuit with zero resistance, one concludes the voltage is zero.

This seems completely wrong.

The justification is given by V=IR. Assuming current is finite you would indeed conclude that V=0. But why would you assume finite current?

Yes, real-world currents must be finite, but real-world resistances must be nonzero. This is an idealization; the idealized values don't have to be physically attainable.

And, in a real-world approximation of an ideal short circuit, one sees very large current; nonzero voltage, infinite current, and infinite power seems like a much more accurate idealization than the finite current, zero voltage, zero power idealization.

Thus my question. Is this idealization of finite current and zero voltage really the common one to make? And why?

Edit: to make it explicitly clear, in this idealization, the parameters of the ideal circuit are allowed to attain idealized values — specifically, a priori, a literally infinite for current is allowed (for mathematical precision, I mean the extended real number ∞). With R=0 and I=∞, Ohm's law puts no constraints on the voltage; every extended real number value for V is consistent.


texts:
simulate this circuit – Schematic created using CircuitLab

Hello!

I have constructed my very first amplifier with 2n3904 transistor, based on the diagram and suggestions from comments from here:
Class A single transistor amplifier with 2N3904.

I know that I'm working close to it's thermal limits, but that's not the problem. You see, when using it everything sounds like it is a earrape remix of the thing i'm playing. Also, RL (47ohm) is getting very hot, almost to the point of it getting dark, while the transistor is only a little bit warm.

At first I constructed it with R1=2.2k, R2=1k, RL=22ohm and the same caps and potentionometer, sound was louder, as expected, but RL(22ohm) started smoking and darkened.

After increasing the resistances to those stated on the schematic the bass problem started. How can I get rid of it?


texts:
I am installing five 12V batteries in a motorhome. The batteries will be wired in parallel for a 12V system and will be contained across three different enclosures.
Each positive cable link between battery enclosures will be fused at either end, as such there will be seven fuses mounted in locations with minimal accessibility.

For this reason I would like there to be an indication light on the outside of each battery enclosure, or a remote monitoring station, to alert of a blown fuse.

I am aware that in many scenarios a 12V LED may be connected across the fuse to light up when the negative side of the fuse is no longer supplied with voltage, however as these fuses will have nominally 12V at both ends I figure this idea won't reliably work.

The solution needs to be economical and reasonably compact, while I am happy for it to be a custom made solution. I appreciate any input.

Edit to add circuit diagram of current layout:


texts: MCP4131 resistor on SDI/SDO multiplexed pin?

texts:
I'm using the MCP4131 digital potentiometer to control the brightness of a LED using an Arduino Uno. The MCP4131's interface is SPI and it has a multiplexed SDI/SDO pin (pin #3).

The datasheet specifies a resistor R1 to be placed on the host's SDO before the host SDI/SDO signal are being multiplexed. I was wondering how to calculate it's value? For now, I used a 1k resistor and it works but I want to learn how to deduce this value from the datasheet.

The comment says that R1 must be sized to ensure VIL and VIH of the devices are met, I can't figure out what these are.

If anyone can explain I'll appreciate it, thank!


texts: Trying to Understand How Honda Ignition Timing Works

texts:
So, I know this isn't an automotive group (per say), but I think that is exactly what I need. In the most simple terms, I've been dissecting my 2001 Honda Accord (3.0 V6 for what it's worth) to understand how the whole ignition/injection system works. Over the past few days, I've been probing around the crank sensor and the TDC (Top Dead Center) sensors to try and understand how the timing is calculated.
The engine has a reluctor wheel behind the crankshaft timing gear, and an inductive pickup, nearby. The confusion started when I looked at the wheel and realized it had 9, equidistant tangs that the pickup sees.
By my understanding, in most cars, you would have a missing tang in this reluctor wheel to help align top dead center of the crankshaft.
So I guess, my question is: How would an inductive pickup be able to determine TDC on this system with these equally spaced teeth? If at all?
It would honestly seem as though Honda is being solely reliant on the TDC/Camshaft sensors. (In fact, the car runs fine without the crank sensor plugged in).


texts: How is a common mode signal generated in a differential amplifier?

texts:
I searched for information about common mode signals but I only got a vague idea about it, such as it is a noise signal generated between input signal and common ground.

However, I do not understand how it is generated in differential amplifier.


texts: Low cost buck SMPS with IC AOZ1284 - 5V x 4A - values for COMP pin

texts:
I want to use a buck converter based on IC AOZ1284PI from Alpha & Omega Semiconductor.
AOZ1284PI is a low cost buck controller. For example, on Digikey it costs USD 0.51 @ 500 whereas the TPS54340 from Texas Instruments costs USD 2.53 @ 500.
The IC support up to 4A of continuous output current, so I want to use it to reduce a 12V rail to a 5V rail capable of delivering 4A.
Below are the parameters that I used to make the calculations using the equations shown in the datasheet.
I have calculated RC to be 180K ohms e CC to be 1.5nF.
I would like to ask if somebody can do a revision on these calculations, and check if these values are really suitable, the value of CC and RC on schematic, that goes connected to COMP pin.

Datasheet:
http://www.aosmd.com/res/data_sheets/AOZ1284PI.pdf

Parameters:

Vfb =  0.8V
Vout = 0.8 + (0.8 * 1800/330) = 5.15V
Iout = 4A
CO = 141uF
COesr = 5 mOhm
inductor = 4.7uH 8x8x4mm (SRN8040TA-4R7M). Current 5.8A. Saturation 6.7A
FSW = around 1MHz (47K 1% resistor)
fc = 30KHz (crossover frequency) or maybe 5khz if better
Vin = 12V
RL = 5.15V / 4A = 1.28 Ohm (datasheets states RL)

Calculations:

fp1 = 1 / (2pi * CO * RL)
fp1 = 1 / (6.28 * 141 uF * 1.28 Ohm)
fp1    = 1 / (6.28 * (141*10^-6) * 1.28)
fp1 = 882.2
fz1 = 1 / (2pi * CO * esrCO)
fz1 = 1 / (2pi * 141 uF * 5 mOhm)
fz1 = 1 / (6.28 * (141*10^-6) * (5*10^-3))
fz1 = 225866.2
RC = fc * (VO/VFB) * ( (2pi * CO) / (GEA*GCS) )
RC = 30000 * (5.15/0.8) * ( (6.28*(141*10^-6)) / ((200*10^-6)*(4.5)) )
RC = 190009.25
RC = 180K...
CC = 1.5 / (2pi * RC * fp1)
CC = 1.5 / (6.28 * 180000 * 882.2)
CC = 1.5*10^-9
CC = 1.5nF...

Then, finally

fp2 = GEA / (2pi * CC * GVEA)
fp2 = (200*10^-6) / (6.28 * (1.5*10^-9) * 500)
fp2 = 42.4
fz2 = 1 / (2pi * CC * RC)
fz2 = 1 / (6.28 * (1.5*10^-9) * (180000))
fz2 = 589

Schamatic:

Below I show my current layout, from top layer:

On the bottom layer, I have a good ground poor.

Regards.

EDIT1
Schematic and layout after user Verbal Kint answered to the question. 12V input, 5V output @ 4A


texts: Where to find ICs in package sizes good for soldering?

texts:
I'd like to know the best places to find ICs that you can solder with. A lot of the package sizes I come across are way too small to solder by hand. I prefer through hole and sockets (like pdip), but ultimately anything with enough pin spacing will work.

In this particular instance, I'm looking for digpots. Although I can find some in pdip, they don't have the right specs: 256 positions, 5k supporting I2C (preferably quad channel, but I can work with single channel).


texts:
Good people of stack. I am a programmer, but new to building my own electronics. I need to switch (3) 12v solenoid valves from the Arduino Micro. I see lots of chatter online, much that confused me greatly.

The valve takes 12v \ 0.3A to close, not sure what inrush there maybe. I don't mind closing on the positive or negative side. Can someone give me a legible sketch of what would be required.

This is the valve being used.


texts: Why is the gate charge curve (Miller plateau) of MOSFETs dependent on Vds?

texts:
I don't understand why the gate charge curve (exactly: the Miller plateau part) of MOSFETs is dependent on the drain-source voltage Vds.

As an example, the datasheet of of the IRFZ44 shows on page 4 (Fig. 6) the gate charge curves for different Vds values.

Why is the Miller plateau longer for bigger Vds? Isn't the plateau dependent upon Cgd? But Cgd (= Crss) gets smaller for bigger Vds (see FIg.5 in datasheet).
Shouldn't the Miller plateau get shorter?


texts:
I'm looking into whether an ungrounded metal box provides good/bad EM shielding.

This thread seems like a definite "good", for reasons of the box acting as a faraday cage : How much shielding does an ungrounded metal box provide?

But when a similar question is asked about ungrounded cable shielding, I am finding some "good" and some "bad". Here is a good: Does an ungrounded shielded cable shield at all?, and #3 of one of the answers is bad: Cable type and decreasing EMI/RFI

"If you don't ground the shield, then it is just a great receiving "antenna" for collecting all your noise, interference, EMI, RFI, etc. And then it is a great method of caacitively coupling all this noise right into your signal wire(s). It is almost worse to have an ungrounded shield than to have no shield at all."

So doesn't an ungrounded cable shield also act like a faraday cage? Is it the fact that the cable shield is physically located closer to the wires that you have to start worrying about capacitive effects?

With that logic, would it be safe to say that an ungrounded metal box provides good EM shielding granted that the electronics you are trying to protect are physically located at a sufficient distance away from the walls of the box?


texts: What happens to unused power in generators

texts:
I have a 7KVA generator which i use for multi-purpose. Some times i run AC on it and some times not. Will the generator consume less fuel when i utilize less power generated from it?

Thanks


texts:
Can a VGA output be used to output an analog signal?
I'm using an FPGA to program and control the VGA output.
I want to use it as a DAC to control an external circuit (I'll be doing PID control). Could I just stick individual wires into ports corresponding to certain colors and program those colors accordingly or is there a better/more efficient method?
My board is the Basys 3.


texts: Explain the logic of a 12 V to 9 V conversion

texts:
How does the below circuit work?

I know what resistors, capacitors, and transistors do and have played with them on a microcontroller board, but am I trying to understand the logic of the circuit.

I assume there is a relationship between the 22 ohm and the 470 ohm resistors.


texts:
So, I'm on a placement as part of my final year of a Masters of Engineering Programme and the company have given me a task concerning a fault they may or may not have with one of their cables.

Basically, the cable in question is designed to carry a power load of 5kW less than what the building it is supplying power to has the ability to draw. I have a list of specifications for the cables but I'm more just looking for advice on relevant resources or equations for my problem rather than just being told the answer if thats possible? I suppose they want to know the circumstances in which their cable will/won't be able to handle the power supply of the building. I thought there would be pretty straight forward equations explaining this kind of engineering but I'm digging myself into a bit of a hole with it all.

How do I size a power cable for a building?


texts: Mosfet Driver - High Side Output Problem

texts:
I've been trying to make a 3 phase inverter to drive a BLDC motor.

Mosfets : IRF3205

Driver   : IR2101

Supply voltage for FETs and drivers : 12V

BLDC : https://media.digikey.com/pdf/Data%20Sheets/Seeed%20Technology/108990010_Web.pdf

I wrote a simple code for Arduino Uno. I change firing sequence of the MOSFETs manually, based on the figure given.

Arduino reads the voltage from the potantiometer and creates frequency range between 15Hz-60Hz in terms of revolution. Duty cycle is 1/3.

The Code:

 int AA1=7;
 int AA2=6;
 int BB1=5;
 int BB2=4;
 int CC1=3;
 int CC2=2;
 int IN=A0;

 void setup() {

  pinMode(AA1,OUTPUT);
  pinMode(AA2,OUTPUT);
  pinMode(BB1,OUTPUT);
  pinMode(BB2,OUTPUT);
  pinMode(CC1,OUTPUT);
  pinMode(CC2,OUTPUT);

}

 void loop() {

 int t =analogRead(IN); //From the potentiometer
 Delay=map(t,0,1024,10000,3000); //we obtain the delay speed using the
potentiometer

  digitalWrite(AA1,LOW);
  digitalWrite(AA2,LOW);
  digitalWrite(BB1,LOW);
  digitalWrite(CC2,LOW);
  digitalWrite(BB2,HIGH);
  digitalWrite(CC1,HIGH);
  delayMicroseconds(Delay);

  digitalWrite(AA2,LOW);
  digitalWrite(BB1,LOW);
  digitalWrite(CC1,LOW);
  digitalWrite(CC2,LOW);
  digitalWrite(AA1,HIGH);
  digitalWrite(BB2,HIGH);
  delayMicroseconds(Delay);

  digitalWrite(AA2,LOW);
  digitalWrite(BB1,LOW);
  digitalWrite(BB2,LOW);
  digitalWrite(CC1,LOW);
  digitalWrite(CC2,HIGH);
  digitalWrite(AA1,HIGH);
  delayMicroseconds(Delay);

  digitalWrite(AA1,LOW);
  digitalWrite(AA2,LOW);
  digitalWrite(BB2,LOW);
  digitalWrite(CC1,LOW);
  digitalWrite(BB1,HIGH);
  digitalWrite(CC2,HIGH);
  delayMicroseconds(Delay);

  digitalWrite(AA1,LOW);
  digitalWrite(BB2,LOW);
  digitalWrite(CC1,LOW);
  digitalWrite(CC2,LOW);
  digitalWrite(AA2,HIGH);
  digitalWrite(BB1,HIGH);
  delayMicroseconds(Delay);

  digitalWrite(AA1,LOW);
  digitalWrite(BB1,LOW);
  digitalWrite(BB2,LOW);
  digitalWrite(CC2,LOW);
  digitalWrite(CC1,HIGH);
  digitalWrite(AA2,HIGH);
  delayMicroseconds(Delay);

}

The problem is there is no PWM signal output at the high side whereas low side has a PWM output. So, the motor does not turn, it just vibrates but not even goes one step.

I calculated the value for bootstrap capacitor and found that around 200-300nF. I think the problem has to do with bootstrapping and I've tried different capacitor values : 220nF, 4.7uF(including electrolyte), 10uF(including electrolyte), 2.2uF(including electrolyte) so far. However, none of them has not worked.

There is only a DC voltage near to 10Vdc at the high side of the driver. When I change capacitors, it's ripple changes but I can't see PWM output.

What could cause the problem ?
Thanks.

Here is my circuit :


texts: Create circuit for 12v auto washer pump to 230v mains with push button for art installation

texts:
I am creating an interactive art installation in a gallery context using a 12 volts car headlight/windshield washer pump. It basically is a fluid washer pump taken outside of a car into a gallery, activated by the user (or spectator) by a switch (a preferably illuminated momentary push button). The whole setup is to be mounted into an insulated vertical box made of bolted metal racks and transparent plastic, so that no water can really get into it. I chose waterproof components for added safety.

The components are all powered by a 10 amps 12 volts laptop power supply connected to the standard European 220v electrical mains.

I am a total beginner when it comes to electrical engineering. I have never really even connected two cables together but I am quite motivated in learning how to do it.

After doing quite a lot of research, I have designed this circuit prototype (which I join to this post), which includes the pump, a relay, a circuit breaker, a switch and the power supply which is to be connected to 230v European mains electrical outlet. The red cables are positive and blacks are ground. My main question would be: are all the cables connected to the right terminals?

And is my circuit design reliable and safe for random people to use in a gallery context, taking into account the potential presence of a small amount of water ?

Here are the components I am planning on using:

The 10 amps 230v to 12v DC laptop power supply I have (will be isolated from any water by plastic panels): https://www.amazon.de/gp/product/B07JC7MJHV/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
A switch example: https://www.ebay.co.uk/itm/12V-16mm-LED-Black-Metal-Push-Button-Panel-Momentary-Switch-Light-Car-Boat-/362525441944?_trksid=p2067104.m45210.l46741  (sub question: Can a higher voltage switch than 12 v be used?)
12 v waterproof 40 amps Relay: https://www.amazon.de/gp/product/B00M2QK47Y/ref=ox_sc_act_title_3?smid=A258M9JSP6L6E7&psc=1
12 v waterproof 50 amps Breaker: https://www.amazon.com/ANJOSHI-Circuit-50A-300A-Protection-Inverter/dp/B07K4ZK4VP/ref=pd_day0_hl_107_1/141-5093642-5255831?_encoding=UTF8&pd_rd_i=B07K4ZK4VP&pd_rd_r=b5db5bcd-ff46-4663-a722-b9c2642abb70&pd_rd_w=EMncz&pd_rd_wg=X9N3j&pf_rd_p=ad07871c-e646-4161-82c7-5ed0d4c85b07&pf_rd_r=SSA0CTQK5SBFV77636NM&psc=1&refRID=SSA0CTQK5SBFV77636NM
Waterproof cable connectors: https://www.amazon.co.uk/Waterproof-Electrical-Connectors-Socket-Marine/dp/B01DVQ2ANO?ref_=fsclp_pl_dp_10
The 12 v headlight washer pump to be powered, tested with the laptop power supply I have and works: https://www.amazon.de/gp/product/B006DHWPOI/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

My questions are:

Is my circuit design correct? Are all the cables connected to the right terminals?
Are these component examples adapted to my usage?
Can a higher voltage rated switch be used in a 12v circuit, all else being equal?
Can I power two systems (the pump and the LED power for the illuminated switch from the same breaker or do I need an additional fuse?

Any advice or help is appreciated to avoid injuring anyone and have a reliable setup that will not break.

Thanks a lot


texts: Simple remote-controlled momentary switch

texts:
I need to create a momentary switch which is controlled remotely, preferably through IR from an old TV remote control (if possible), in order to answer my office door buzzer without getting up.

On the panel for the buzzer, there is an unlock push button, which opens the door while you hold it pressed, and locks when you release it, so I would like to keep this functionality but add an IR receiver which would do the same in parallel.

So far, this is what I've found: https://www.aliexpress.com/item/IR-DC-5v-Remote-Control-Switch-1-Channel-Relay-Module-Board-With-1-key-Infrared-WirelessTransmitter/32654853261.html?spm=2114.40010308.4.148.9TTPdO

My problem is that the product is not sufficiently documented, so I'm worried about the exact pinout and wiring of the device. There is a pinout but it's in Chinese and is not documented properly. If anyone has had experience with one of these, could you please explain its pinout and functionality, so that I know what I'm buying and how I'm going to use it?


texts:
I'm considering building my own power strip for multiple different reasons.
I've been trying to research these, but haven't found much information.
I obviously know what makes up a power strip, but I'm wondering if the copper(?) rails within the strip housing are something you can buy premade and then build the housing myself? If so, what would these rails be called?
Thanks!


texts: Every datasheet that I have looked at mentions the function of pins A, B and C but no mention of D and E. I'm unsure which one is the push button output and which one is the Ground pin. I'm currently looking at this one: http://uk.rs-online.com/web/p/mechanical-rotary-encoders/6234237/


texts: Getting bizarre results with 12V LED driver power supply

texts:
I am using this supply to provide 12V to my system.
https://www.amazon.com/gp/product/B07D9FTC77
I have a DC-DC voltage adapter that converts the 12V down to 5V to power a Raspberry Pi Zero. (The 12V is needed to power something else in the system.)
When using the LED driver, the Raspberry Pi seems to work fine.
However, I am using a sensor with the Pi that does not work properly. If I switch to a regular 12V power supply (like a wall wart) everything works perfectly.
Is there something different or wrong with this LED driver? I get the same 5V reading no matter which supply I use.
If this is not the correct type of supply one should use for powering a Raspberry Pi, are there any affordable, waterproof supplies like this that are? Because every waterproof supply I can find seems to say it is for LED lights (though this one even says it is also for other things like computer equipment.)


texts: How to decipher coding on Voltage Regulator

texts: I am looking to replace the voltage regulator above but I am not able to find an exact replacement and am not sure what the last three digits "203" stand for. Can anyone help me out?


texts: How to simplify the next boolean algebra expresion?

texts:
Im trying to do the next simplication of the next boolean algebra term
\$\bar{A}BC+A(\bar{A}C+B\bar{C})\$
In this way

\$\bar{A}BC+A\bar{A}C+AB\bar{C}\$

\$\bar{A}BC+0+AB\bar{C}\$

\$B(\bar{A}C+A\bar{C})\$

But whats next?
If I try to multiply by 1 , it ended changing the negation

\$B(A\bar{C}+\bar{A}C)\$\$

UPDATE
Based on an answer deleted and the DeMorgan Law
\$B(\bar{A}C+A\bar{C})\$

\$B(\overline{\bar{A}C+A\bar{C}})\$

\$B(\overline{\bar{A}C})(\overline{A\bar{C}})\$

\$B(A+\overline{C})(\overline{A}+C)\$

\$B(A\bar{A}+AC+\overline{AC}+C\bar{C})\$

\$B(AC+\overline{AC})\$

\$B(1)\$

\$B\$


texts: Powering up arduino with Xbee and a 6V (run on 5V) motor

texts:
I am working on a small project where i'll need an arduino to control a motor wirelessly using Xbees.

I have a 7.4v lipo battery

I am wondering will there be a problem or insuffciency if i only use this 7.4v battery to power up the Xbee-attached Arduino and the motor (DC motor controlled by a driver board) which will be supplied with 5V getting from the arduino?

Here I relate to another problem, as I am wondering if it is because of insufficient power supply:My Xbee module is behaving kinda weird. When i try to control the motor wirelessly through signals from the Xbee, the motor isn't running until I press down on some area of the Xbee module mounted on the shield attached to the Arduino

I don't think it is merely any loose pins connection of the Xbee and Arduino or the shield, because I have tested the Xbees with LEDs, they are communicating well.

so, my question now, my 6v (run on 5v) motor is not responding well to my inputs from the Xbee-attached-Arduino, is it something to do with my power supply method?

Hope you guys could help!
Thanks in advance!


texts: FCC Part 15 Class B Declaration of Conformity (DoC)

texts:
I'm familiar with Part 15 FCC testing for intentional radiators (3 meter limits of certain power, must be filed with FCC, requires accredited lab), but I'm a little unclear on the Class B unintentional radiators?

I know from another product we received a Declaration of Conformity for the Class B limits, and that nothing was filed with the FCC.  As the "responsible" party we make the certification the product conforms to Part 15 Class B.

Are we required to use an accredited lab for the Class B unintentional measurements?  We have a LISN and 30MHz to 1000MHz EMI antenna in house.  Ultimately, my company's you know what, is on the line as the certifying party.  So why can't we take the readings, and certify?

The only place I read that the Class B DoCs must come from accredited labs, are from the websites of accredited labs!


texts: How do I know that this BJT is in the saturation zone without having to simulate it?

texts:
I have to find the working zone of this BJT, for different values of P, by using a simulation software like Simulink. But I would like to know how to do it manually. The way I learned is sort of guessing if the collector and emitter voltages are higher or lower than the base voltage.
In this circuit the zener voltage is 5.1V and the LED forward bias is 2V.


texts: Why the spring on (-) polarity at the alkaline battery 1.5v gets eroded

texts: I have small toy and it’s not used for three weeks, later I found out one side of the battery holder at (-) negative polarity spring got eroded. I knew battery gets discharged without using the device but how come the chemical reaction occurred and  entire spring disintegrated?


texts: How to calculate a voltage/current controller bandwidth based on their gains Kp and Ki?

texts:
I am doing some experiments with voltage and current controllers, but sometimes my results are not matching what I expected. At the moment, to calculate the bandwidth of a controller, I am taking the absolute value of its open-loop transfer function, and setting it equal to -3dB (0.86), which gave me the following equation for the bandwidth of a PI controller:

bandwidth = \$\frac{K_i}{\sqrt{0.739 - K_p^2}}\$

What am I missing?

Thank you in advance for the assistance in this matter.


texts: How to implement an equation in assembly language using PIC18F and display its result on LCD?

texts:
I had a project that requires to measure illuminance(lux) using LDR and display the result on LCD. Thanks to some references from Google, I had managed to build a equation that shows relation between Lux and LDR's resistance which is:
L = 1,48.(10^7).R^(-1,43)

ADC input is voltage divider of LDR( as image showed below)

The equation above could be described by the following equation:

Cause I'm using PIC18F with 10bit of ADC resolution and the reference voltage used is 5v so resolution of ADC module should be 4.88mV. Thus, I can get ADC value stored in ADRESH and ADREL to multiple with ADC resolution for achieving Vadc at the input as well as value of illuminance. So the questions are:

I found some sources said that the value in ADRESH and ADRESL should be combined to a 16 bit registor by multiplying ADRESH with 256 then add them with ADRESL. But where will the result be stored when all of registers in PIC are 8 bit length?
Suppose that the first problem was solved, the next one is how to implement the complicated equation above in assembly language. It is too tough for me! :))
If the first two questions have been handled, an another problem arise when we display the final result on LCD( it's definitely a float number). How can we do that?

I appologize for asking so many questions in a post but you know, I always think it out before posting anything here and these question did make me headache for days. I will really appreciate for your help.
Thank you.


texts: emergency battery and dimmer in parallel

texts:
Working in a theater, I do have lights in the stairs, that I can dimm. But in my country, it is mandatory that those get light up if the main fuse is cut, as emergency lights, with a battery.

So, I'd like to add an emergency battery. This emergency battery only outputs power if the switchboard doesn't.

My goal is this :

When power outage, the light bulbs outputs 100%
When no power outage, you can choose the intensity (or shut it down) with the dimmer switch

Is this a good schematic idea ?

simulate this circuit – Schematic created using CircuitLab


texts: Does multipath apply to sub-1kHz signals?

texts:
Based on my (currently naive) understanding of EM field propagation, it would seem that in the near field (e.g. <10m), low frequency (e.g. sub-1kHz) signals would be oscillating so slow such that any discrepancies in the time to reach the receiver from different paths (due to speed of light) would be negligible.

Is this true?


texts: Triac BT 136 getting shorted when load is given to T1

texts:
We have a optocoupler switching circuit which triggers the TRIAC with ZCD. Everything is working fine with all inputs. Connection is

T2 as a input
T1 as output
Gate as Trigger from Optocoupler

As attached in image.

If We give direct load in T1, We get same load in T2 even when gate is not is untouched or closed.

Once this happened, Triac is shorted (when we check continuity T2 and T1 are always connected even Gate closed). If anything can be done to prevent to reverse flow when I trigger external switch.

Please help us on this...

simulate this circuit – Schematic created using CircuitLab

Figure 2. CircuitLab version by @Transistor for OP to edit if not correct.


texts: Definition of Source Power for RF Transmisison Line Source

texts:
So I know this is going to seem like a very simple question, but my book provides no definition. If the power P_in is defined as the power the goes from the source into the load in a transmission line, what is the source power in terms of the generator voltage, generator internal resistance, and any other relevant constants.

I've seen elsewhere the book that $$P = \frac{1}{2} Re\{VI^*\}$$. In the case of a generator with some internal impedance (resistance in the simple case) Z_G and some voltage source V_G what is the power it can deliver
$$\frac{V_G^2}{Z_G}$$ or
$$\frac{1}{2} \frac{V_G^2}{Z_G}$$ and why?

I'm just not fundamentally understanding all our different power definitions for these problems, and it would be very helpful if someone could provide a concise summary of what I need to know to tell what's going on. Thanks.


texts: Beta reduction capacitor in Sziklai Pair speaker driver

texts:
Final installment (promise!) in my set of metal detector circuit questions.  This time it's the speaker driver (see images below).
When I first saw this, I thought - no problem it's a sziklai pair, which the AoE describes as a super-beta darlington like combination with a lower Vbe.
I also figured that the 470uF cap was just for smoothing Vcc...I was wrong (again).

Some breadboard analysis and spice (see images below) tells the story.  The cap charges up to hold the voltage at the emitter of Q2 at a saturation voltage above the collector.  This (it would seem) kills the beta of Q2 and the overall beta of the sziklai pair drops to (by my calculation) around 25.

I measured the Ib flowing to Q1 on the breadboard (and spice concurs) and it's ~40mA.  This all points to the same conclusion: the cap is driving the pair into saturation and the beta is reduced.

But what I can't understand is why?  Why would the designer do this?

By the way, in case you're confused by the spice images, I upped the freq from the 555 to 400Hz because I found the 4Hz ticking in the original to be less effective.  But, I don't think it alters the general idea of the capacitor.

Complete original documentation to be found here.

Update:

I thought I'd simulated the original circuit with a frequency of 4Hz and a 8 ohm speaker, but obviously not (or not correctly).  Anyway, it seems that the speaker I'm using (4ohm 2W) is simply too heavy a load for the driver, causing the driver to saturate.  Other than that the intention of C1/R2 is all of the points Jim mentions in the comments.  Thankyou.


texts: Arduino - interrupt based decoding of serial data, race between ISR and loop()

texts:
Trying to decode serial data (encoded using proprietary method) from a RF module.

Having switched back and forth between the fast-sampling (4x the fastest freq) and of late an interrupt based method, I've reached a dead-end and not sure what all I am doing wrong, because apparently people have been successful in decoding ISM-band RF data (Manchester, NRZ, VirtualWire and HT12E/PT2260-62 encoded), in software.

In my case, the RF modules's AGC (which I've no idea how to turn off, since there's no data-sheet, and the co. doesn't respond to emails... a cheap east-asian make) picks up noise and has the fastest level-transitions in durations ~40us, although valid (encoded data) transitions not lesser than 400us. My ISR has an elementary task of measuring the duration of last state to reject the spurious noise, and save only those transitions that could possibly be part of the encoded data. So far, I have not used a circular-queue (which is what I plan as the next step), but before doing that, I did a small experiment. In the ISR I check the state of a flag to see if it is true, and if true I do Serial.print("x"), else I set it true. In the loop(), I check if flag is true, then do Serial.print("-") and set it false. The flag is declared volatile. I find that I get very long continous streams of "x"s and very rare "-". My ISR is triggering on every transition of pin-2 (i.e. external interrupt#0).

Now my question is, would adding a queue really solve my problem, because apparently the ISR is running far too frequently and thereby starving my loop() of cycles.  Counting the distance between the "x"s and "-", I was hoping to find the ideal queue length, but I can't figure out a pattern. Is there something inherently wrong in my approach ?

An outline of the source code is here.


texts: Referencing multiple differential pairs to ground before analog multiplexer

texts:
Yesterday I asked how to properly reference a differential signal (in my case from a current transformer) to ground, and got told that the impedance to ground should be matched at the location where my differential signal amplifier is.
What if in addition I have multiple differential pairs which I would like to multiplex into the signal amp using an analog multiplexer IC? The problem is just that certainly all of the pairs still need to be referenced to ground somehow before going into the multiplexer IC, but I don't want to duplicate the amp for each input pair.
Would, for example, connecting one side of each of the differential signals to ground through a ~1 megaohm resistor be suitable?


texts:
I have six 2012-2018 TESLA MODEL S MODULES I have been using two in series for a 48 volt inverter with no BMS (set the low voltage and high voltage limits accordingly). Now that my energy needs are greater I want to use the other 4 modules.
I want to connect the Modules in a 3p2s configuration and each module is a 74p6s.
I know this can be done with very expensive BMSs like an Orion but I wonder if it's possible to use a cheaper BMS like a Daly on each module or if that would just create more issues.
Open to suggestions!!! I just need the voltage to be around 48 for my XW 6848.


texts: Identifying damaged, burnt out, or missing components

texts:
Is it possible to deduce the identity of damaged, burnt out, or otherwise missing components (or suitable substitutes)?

For example, below is the PCB of a 2 speed electric razor I've disassembled. The missing component had three legs, like a transistor. It originally had writing on it, but was covered in what I can only describe as a thin white layer of soot/charcoal. I tried to clean it by gently swabbing it with an isopropyl alcohol solution and soft brush; it just crumbled to pieces.

The low battery LED is constantly lit and the NiMH cells hold a charge, but the electric motor will not engage. It was left on charge overnight, as usual. When I went to use it the next day, it was hot and non-responsive.

This is all the remains of the absent component.


texts: A really basic question about ammeters and their ranges

texts:
I was performing a basic verification of Ohm's law in a DC circuit experiment the other day, during my exams and I mistakenly used an ammeter with range 0-10A instead of the 0-1A ammeter that the practical manual expects us to use.

The invigilator/examiner noticed this error and told me that this is a really bad error on my part and this will not be forgiven. She cut half my marks just because of this small error(?).  I retorted by saying that it shouldn't really matter, because all I am doing is just reading the current value in the circuit and the range of the ammeter used won't affect that value. She said that isn't the case and the range of the ammeter WILL affect the current reading. I didn't know much of the specifics about the working of an ammeter, so I just ignored her. I don't even care about the marks too.

All I want to know is whether the range of the ammeter affects the current reading shown by it? If possible, I also want to know how the current value is affected just by swapping it out with an ammeter of a different range.

I looked up the working of an ammeter and I found that an ammeter is just a galvanometer with a resistance in parallel (I don't understand what they mean by parallel). Maybe the resistance increases the overall resistance of the circuit and hence leads to decrease in current(?). Please let me know if my speculation is correct or not. Thanks in advance for tolerating my zero knowledge of the subject :)


texts: I just bought a pic 32 starter kit, and since I did little reading before I picked up the product I found that it came with no simple way of accessing the pic32's input and output. I know there is a pic32 expansion board but I am feeling a little bit burnt by microchip for even suggesting that I need to get an expansion board for my starter kit... anyways before I start ranting, What options do I have to getting simple access the pins? there is a connector on the bottom of the starter kit, I was wondering if there was a standard cable that would fit into that? I just don't see the need buying a 72 dollar board when a bit of wire should do the trick? anyways I would greatly appreciate any advice that can be given


texts: why capacitors are used with crystal oscillator?

texts: I want to learn 8051 programming so I begin from hardware in which crystal oscillator is connected with capacitors.  can anyone please explain why capacitors are used and why those 22pF? how they calculated?


texts: What type of connector is this (16-pin, 1-row)?

texts:
I came across a (dead) board and am trying to figure out how it might be revived. The board has this connector, which seems to be connected to a
ADSP-BF533 processor. From BF533's specification I believe that it might be an (unusual) representation of a JTAG port. To figure out a possible pin assignment it would be nice to know the type of connector, maybe it has been used as a JTAG port somewhere else?
Unfortunately, even after hours of looking through connector catalogs I have not been able to figure out what kind of plug this might be. It is 19mm wide and has 16 pins pitched by 1mm.


texts: Swapping two 500kohm pots with one MCP42010 10k ohm digital pot

texts:
What additional elements do I need in my circuit to compensate for changing a pair of manual 500k ohm pots to a pair of digital 10 ohms?

I'm a beginner implementing an Atari Punk Console on Raspberry Pi following a circuit I found online.  That circuit called for two 500k ohm variable resistors that are used in combination to vary the sound coming from the device.  I want that effect-making under computer control so I swapped in a 42010 digital pot (which has two pots built in) but which only has 10k ohm resistance per resistor.  The circuit works but the volume is less substantial than the original and the range of impact of effective digital values is small, with the effect only occurring on the low end from 1 to 100 on one, and 1 to 60 on the other.  I guess that is to be expected insofar as it's at the higher resistances that the interesting sounds might be.

There is also a NE556N timer involved in the circuit.  I've adapted it to the Raspberry Pi and I'm using 3.3 volts.  Here's the circuit I started from:

Atari Punk Console

Here's the data sheet for the MCP42010:

MCP42010 Datasheet


texts:
I am trying to calculate the duty cycle of the buck converter as in the figure for discontinuous conduction mode of operation. I have worked to the math and have got the following graph as in the picture-

The Duty cycle depends on the load current. How we find out the on time if we do not have the load current?


texts: How Home HVAC controller send commands for Cooling, Heating?

texts:
i want to know how the Hvac controller sends commands to the hvac for cooling and heating.
i mean when we push on + or - button for example to adjust the temperature, what happens on the other side? is it simple contact which activate the cooling for certain time ?
I did not find any schematics google.
Can anyone explain how it works.

My project is to replace the HVAC controller with a Raspberry pi card.
i saw in some documentation:
W = heater control line
Y = Cooler compressor
RH = Heat/Cooler power
G = Fan control
C = Option

for example i want to adjust a cooling, when i push the button -, am i send a signal like close contact between 0V and Y ?

Thank you


texts: I took apart a Kenmore microwave in order to salvage the magnetron, transformer, and the HV capacitor. The transformers, HV capacitor, and the magnetron from the microwave are intact. Is it possible to make the magnetron work without the microcomputer panel?


texts: Masterthesis - optimization/design a board - help required

texts:
For my master thesis I have to optimize a already build board that was only quick made on a previous master thesis. The Board itself is not that complex and works as an actuator controller via a microcontroller (ESP32). Overall my knowledge for design is low-decent, but that's the thing I like as I learn something new everyday. But I am scared to get lost on the way and cant even finishes the basic requirements till the deadline arrives.
Previous Version:
Uses an external ESP32 via a pin header to control around 16~ NMOS who control the actuators(12/24V, 10-500mA different kind of actuators) also some sensor are controlled aswell. The ESP32 get's it data via WLAN over MQTT/JSON Data.
As for the optimization I need to implement Ethernet (I will use an LAN8720A and the internal MAC from the ESP32 because of stability and speed). A stable power regulation with Vin in range of 12-24V and Vout of 12V with enough Amps for all the actuators(Around 8A max.)
Because the ESP32 has to few pins for everything I need, I use I2C MCP23008 expanders to control the logic level MOSFET. 2 x 8 allows me to control all my 16 FETs with enough current for switching (Maybe even a level shifter to 5V for a bit more switching power?)
Overall, as you can see in all of my previous posts I already asked ALOT and will probly. Do even more and I am so thankful for every help I get here.
Over a month and a half are now over and I have 5 month overall. So not that much left as I still need to order the PCB which takes a few weeks, code the ESP32 and need to write the text aswell.
Now my questions:
What is the best way to do further? What is the typical way if someone designs or optimizes an already existing layout? I know I should have asked this probly. At the beginning but I feel like only now I have the complete picture of my task.
I am already at the part of designing the layout. ( we try to use through-hole because it's simpler but some things can't be done there)
What would be my next step? I thought about making a small prototype now with only the important stuff to work on the coding and maybe check if the overall master layout needs to be done better...
If you could guide me, I would be really thankful.
EDIT:
Maybe the text was misguiding as english is not my native language.
I don't want a someone to design it for me. That is my task.
I would just like to have some tips and guidance for what are common steps, where do mistakes happen a lot and what should I watch when I am designing. Obsiously I will still do mistakes as that are what thesises are about and how to solve them but I don't want to run into a "dead-end" !
Greetings.
PS: If you need more information or anything else just ask.


texts: In Verilog can I use the same wire as both an input and output to a module

texts:
This is what I mean:

module someModule(~);
wire w;
someOtherModule m0 (.input(w), .output(w));
endmodule

Would something like this be legal?


texts: Detect movement in a very power efficient way

texts:
I am working on a device i can strap on to an expensive electronics instrument, and when someone moves the instrument, the device detects it and sends its position from a GPS to a server, via WiFi, where people can do a look-up on the instruments last known location.

The device will need to run on a battery, so the whole setup needs to be as power efficient as possible.

The WiFi chip i am using is the ESP8266. Not a big surprise, i know, but it has a decent range, doesn't consume much power in sleep mode (around 20uA if memory serves me right) and is cheap as wood.

Next challenge. I need a way to detect movement in a "as low power as possible" way, so i went digging, and found a couple of ways. There is a kind of switches that can detect movement, either by rolling a ball to make contact or by moving a spring to make contact (Spring switch), but i want it to be omni directional, so no "rolling ball switch", and i want it to be sensitive enough to detect when the instrument is moved, and i haven't been able to find a "spring switch" with enough sensitivity.

There is also the possibility to use an accelerometer to detect movement, but that consumes a lot of power. At least, that's what i believe.

But! I found an accelerometer which i think gives a power saving way to wake the ESP8266 when movement is detected.
The accelerometer is a MMA7660FC, made by NXP (Datasheet). In the datasheet on page 13, under "Auto-Wake/Sleep", i interpret what they write as the accelerometer can sleep until a directional change is detected and provide an interrupt signal, which i can use to wake up the ESP8266!

So, here comes the two questions i have:

Is what i am saying about the MMA7660FC true? Its not the ideal solution because of the current it will draw, even if it is sleeping, but it is better having to change the battery a little more than having a failed project.
Is there a way to detect movement that i have missed and is useful for my application?

Thanks in advance :)


texts: Can an electric field have Electric potential difference with only one charge?

texts:
I know that when you have a charge, it creates an electric field that is equipotential. So, can you have potential difference without adding another charge? Maybe putting a material across the electric field.

Formula for electric potential at one point:

$$V(Q,r) = \frac{1}{4\pi\epsilon_0} \times \frac{Q}{r^2}$$

Being \$\epsilon_0\$ the permittivity constant for the vacuum


texts:
I am trying to simplify my noise source circuit from the first design to the second. Can anyone help me correct the values I need to do this as lost and a novice?

Also, will this produce noise as I am attempting to do?

Thanks in advance.


texts: Solar panel strings: when does current flow via bypass diodes where each panel has a different maximum power point?

texts:
When having strings of 5 till 6 a-Si/µ-Si thin film PV panels and each panel its junction box is containing a BY255 by-pass diode, to make sure that current will flow in less optimal situations, like partially shaded/broken panels.

I am now wondering how current will flow in less optimal situations, for example one PV panel receives 200 Watt/m2 and other one 1000 Watt/m2. In other words: one panel in the string would could generate a current of 1.5 amps at its maximum power point while another will only generate 0.3 amps.

Will the string now produce/generate 1.5 amps of current? Will at the shaded panel 1.2 amps of current will flow via the bypass diode, and the other 0.3 amps through the PV cells? I guess not because of the potential difference: some 80-90 volts over the cells, and maybe -1 volt (the voltage drop) over the diode. So my guess is that only 0.3 amps will flow, but when will the bypass diode in the PV junction box carry current? Where are tipping points?

The answer in question regarding How does physical damage affect the performance of photovoltaic cells? does explain something related, though I still don't understand the role of the bypass diode.


texts:
How big a threat is electrostatic discharge ESD to typical integrated circuits, really?

OPINIONS VERSUS EXPERIENCE

I am not especially looking for opinions (indeed, uninformed opinions on this topic are easy to find), but for quantifiable or quasiquantifiable experience of the actual destruction of hardware. (For example, if you work in an electronics assembly plant and are familiar with the quantity of hardware that gets thrown in the plant's trash bin due to ESD events, then you have legitimate, quasiquantifiable experience; but if you have merely read the plethora of service manuals that warn against ESD, then you might have no more than an opinion.)

BACKGROUND

I ask because (a) I hold a master's degree in electrical engineering, (b) the focus of my master's study was in electromagnetics, (c) I do not however work professionally in the fields of electromagnetics or electronics, (d) I have not always been very careful while disassembling electronics at home, and (e) except due to lightning, I have never once witnessed the destruction of electronics by ESD. I have repeatedly, unfortunately witnessed the destruction of electronics by inadvertent connection under power to wrong impedances, but never by ESD.

I am 49 years old and, perhaps like you, have been disassembling electronics at home since I was 13. I am not always careless (it depends on the value of the electronics I am handling, how much time I have, etc.) and I do own an ESD wrist strap, but I have been careless enough without apparent consequence for so many years that I begin to notice that my own experience seems to contradict the conventional warnings. What's going on?

Some of the warnings recently say that ESD "degrades" electronics. But does it, really? Quantifiably, how much?

Also, I ask because I instruct engineering courses part-time at a state college, the E.E. undergraduates there all have FPGA prototype boards, and some of the undergraduates just toss the boards in their backpacks. I have yet to hear one of these undergraduates mourning the loss of his or her FPGA to ESD—though, admittedly, I have not myself taught any of the courses in which the FPGAs are used.

REMARKS

So, is there any quantifiable or quasiquantifiable experience of this? Or is ESD not quantifiably much of a threat, despite all the (suspiciously bossy, suspiciously nondetailed) warnings the service manuals convey?

See also this answer.


texts:
So I am trying to interface a slave device to a master uC through an ADUM4151 SPI Isolator and am getting confused on where I need pullups for the MISO line as I see it a few ways in reference designs.

My slave device's MISO is open drain, so he needs a 5k pullup.  I'm then putting him through the ADUM4151 and straight to my uC (through 100ohm resistor).  I don't have any other slaves on the bus so I figure this should be the end of it.  However, I see a few designs where a schottky diode is placed with its cathode facing the output on the isolated/uC side of the isolator and then another pullup before going to the uC.

Can anyone explain to me what the point of that would be?  I've read a few things stating it "converts the isolators push-pull output to open drain."  But seems like I'm going to be sending current into an output pin through the diode when MISO is pulled low.  I figure it'd only be useful with other slaves on the processor side of the isolation so I probably don't need it, but would like to understand the point/purpose.


texts:
I'm working on a project in which an MSP430 is used to provide the timing for some stuff where accurate timing is important (it can be off by 10%, but not by 2x).  This is driven by the timer A0 running from the SMCLK clock source in this case.  I would like a self-test function by which I can check that the MSP430 clock is not too far from spec (it is supposed to be 25MHz).  In particular, I am concerned about failure modes (even though unlikely) that drop the MSP430 high speed clock down to a really low value (kHz) even though the chip keeps running: that would be catastrophic as far as the rest of the hardware is concerned.  There is a 32kHz clock from a crystal on this board.

(1) Is there a library function (msp430ware, etc) for checking that the clocks are ok?

(2) Can I use the 32kHz clock to check the high speed clock?  What is the best way of doing that?

(3) What clock integrity features are there on the MSP430?

Thanks!


texts: Question about the role of specific element in a circuit (H Bridge)

texts: I am currently studying different ways to design an H - Bridge and came across this circuit. I have a good idea how the bridge works except for the two transistors on the bottom that I have red circled. When I cut them off and simulate the circuit it seems that they do not affect the outcome at all. What is their use? Some sort of protection maybe?


texts:
I have a small problem with my LTspice simulation...
When you have a system that contains multiple capacitors, inductors and resistors, how do you know, when you measure its equivalent impedance Z using an .ac simulation in LTspice (for example), what components resonate (which L with which C). To give you guys a context, I have [this][2] schematic below, that has the same resonance frequency (but not the same amplitude though) to same schematic but with different values of the parameters: R12, C12, R13, C13, Rm1, Cm1, Rm2, Cm2, Rm3, Cm3. Does this seem reasonable to you guys? or do you think I am doing something wrong somewhere?


texts:
Ive defined for my project a Single-Port ROM, using the Block Memory Generator of ISE tools.
It appears as part of my project, but i'm having a error message implementing my top module. wich says:

ERROR:HDLParsers:709 - "C:/Users/Neander/Project/SinHandler.vhd" Line 56. memory_sin is not an entity name

Here's my .vhd:

memory: entity work.memory_sin -- BRAM with the sin values
    port map(
    clka => clk,
    addra => mem_addr,
    douta => dout);


texts: Eagle layout: how do I create an elongated hole under IC for isolation?

texts: I am kind of new to Eagle. I need to put a hole under an IC for isolation. An elongated oval to separate the sides of the chip. I need to be pointed in the right direction.


texts: Determining which pin triggered a PCINTn interrupt?

texts: Am I correct in thinking that if you have two pins causing the same AVR PCINT interrupt, (e.g. PCINT0 vector caused by either PCINT0 or PCINT1 pins -- I think the naming overlap of vectors and pins is confusing) the only way to determine which pin(s) caused the interrupt is to record their state after each interrupt and compare the previous and current values of all the pins which are enabled in PCMSKn?


texts:
Using Eagle for mac, I am trying to autoroute the board. I have set the trace width to 8.
He start the process and it takes him about 2 minutes, than he stops at some point and show the next percentage (see the image ).

Why it stops on 84%? I could see other people on 97% , but why is that?
How can I fix that in the most fastest and simplest way?


texts: Is a IIR digital filter with a0=1 effectively a FIR digital filter?

texts:
I have been experimenting with several digital filters for my thesis recently, and while learning about the FIR and IIR kind, they seem to have similar output expressions.

While using a Java class I found online to design a Butterworth IIR Filter's coefficients, I realized that the 'a0' value turns out to be 1 and, consequentially, that the resulting expression looks like a FIR filter.

Is this the case? Or is the fact that the 'y[n-i]' terms are present on the final implementation enough to warrant it not being FIR and definitely IIR?


texts: I'm trying to drive an LED with a square wave / pulses and look at the output with a photodiode / transimpedance amp detector.  The starting frequency is about 1 KHz but I will eventually go up to about 100 Khz.  The problem I'm running into is non-square LED output waveforms being sensed by the detector.  In the scope capture, channel 1 is the driving waveform, channel 4 is the signal at the LED and channel 3 is the detector output.  My first thought was to try a different LED driver circuit, specifically a shunt driver configuration.  I read online that adding some RC components could speed it up (increase the slew rate).  I found on another site something similar albeit a digital driver that uses dual inverters as drivers.  Could someone explain to me what these RC networks are doing (specifically) and how to determine the appropriate values for them?  Thanks in advance.


texts: I am completely blanking on what this component is called/what it does. Can someone help me out...   -_-


texts:
I'm a beginner to all this and have had a little bit of trouble understanding how exactly these tables work outside their base examples.

I've made an attempt at drawing a diagram from a table that has 2 states and two outputs from 1 output and I'm mostly wanting confirmation that I am going about this correctly.

Thanks in advance!


texts: Determining drill size for panel mount components

texts:
Many components can be panel-mounted by drilling a hole through the panel and then fixing in place with a washer+nut. However, sometimes the datasheet does not specify what is the hole size to drill. For example, the datasheet for this panel-mounted push button includes diameters at different points in the component, but no hole size:

Should the hole size just be 7mm (major diameter of an M7 thread)? Or is it recommended to make the hole slightly wider?


texts:
Can anyone explain - what is the difference between static and varying electro-magnetic fields?

I know the definition for what is static electric field. It does not change with time (0Hz frequency.) But I don't know the exact meaning of that.

Also, can a Faraday cage stop only the static electric field? Can it shield both the static or varying magnetic fields? How?


texts: Can ARM MBED be legally and robustly used in commercial products?

texts:
I'm looking for a simple but reliable microcontroller platform (chip plus API) for modules that will be integrated in a product that we are developing for a customer (in this case a 8 channels RS232 current sensor based on ACS714 but this question is meant to have a broader scope).

In a previous thread someone mentioned the MBED platforms, and after some research I found the Cortex M0 (LPC1114) and the MBED libraries were a good match.

It sounds like the MBED libraries are more "professional" than the Arduino, but I do not know its story and I can't spot any flaws in the code. What is your experience and knowledge of the MBED platform when it comes to integrating it into commercial products?

P.S. I think here is more appropriate than stack overflow as it is related to hardware level programming.


texts:
I was solving some problems with RL circuits today and a thought occurred to me that I couldn't answer. Say you have a Vsource Resistor and Inductor all nicely in a loop. You let the voltage source run until everything reaches a happy steady state. The Inductor should have energy

$$E = \frac{1}{2}L \frac{V^2}{R^2}$$

Now, what happens if I cut the wire? Where does the energy go?

Sorry for the needless schematic... I just discovered the feature and thought it was cool. :)

simulate this circuit – Schematic created using CircuitLab


texts:
I have intel dc 12v cpu fan (removed from a computer) that has 4 wires (Black Yellow Green Blue)
(Model E97379)
[Photo- http://www.filetolink.com/c50ea25682 ]

I want to power it by ac to dc 12v adapter.

What wires i should connect to my adapter ?


texts: I have a hardware-only Conway "Life Machine", is that interesting?

texts:
I just finished making a hardware only Life Machine™ on breadboard using 74LSxx chips. I call it The Life Machine™ or Life from Scratch™. It works on an analog oscilloscope in X-Y-Z mode. The field is 256 x 256 pixels in size, and it is set up to run at 4 MHz at a 60 Hz frame-rate, but because of some glitching with the capacitance issues on the breadboard setup, it works well at 1 MHz, 15 Hz framerate. There is one generation per frame, so the design, if properly moved onto a reasonable PCB or wire-wrap board would probably be easily scaleable to a field of 512 x 512 pixels at 60 Hz with an 16 MHz crystal or from there onward. (Thinking about doing a VGA 800x600 mode or jumping straight to HDMI 1080.)
My algorithm is quite highly optimized so that it runs in a single pass. There is no CPU involved and no micro-controller, no code, its 100% pure hardware automaton. No FPGA. Just RAM, counters, bus transceivers, latches, and a hard-wired neighbor-count-adder with one breadboard slice of 1-bit full-adders, AND, OR, XOR, and inverter chips. No higher order display chip either, even the DAC for the X-Y deflection I made myself from R-2R resistor ladders. And you were all part of it since I had a number of questions recently to all sorts of different aspects of this.
I wonder whether there is interest in this or if this has been done many times before? I wonder how I should publish this? Do you think there is any journal that would have any interest in this? I could imagine I am perhaps 40 years late to the party, but when googling I have not found nether the hardware only setup quite like mine nor have I found my algorithm being discussed and the way it's implemented. I find my solution very nifty.
Are there still hobby-electronics or semi-professional magazines or journals around these days? Or might some IEEE journal be interested in this?


texts: What happens if you connect a "slant 45 radio unit" to a linear parabolic antenna?

texts:
If I understand it correctly the only difference between linear polarization and slant polarization is that slant polarization is just a 45-degree rotated version of linear polarization, and that polarization is something that is controlled by antenna, not by radio unit.
But it seems that a "slant 45 radio unit" cannot be directly connected to a linear parabolic antenna. Take a look at this radio unit from Ubiquiti Networks:
https://dl.ubnt.com/datasheets/airfiber/airFiber_5XHD_DS.pdf
This is a microwave (5 GHz) dual polarization radio unit. It connects directly to a slant 45 parabolic antenna. It can also be connected to a linear antenna but it needs a linear to slant 45 converter.
Basically the reason why a converter is needed is to maintain the polarization to slant 45. I think that makes sense if, for example, the transmitter antenna is linear and the receiver antenna is slant 45; you need to make each antenna the same polarization and in this case you convert the transmitter antenna from linear to slant 45. But what if, for example, both the transmitter and receiver antennas are linear, and the radios are "slant 45 radios", is a converter still required?
Is there such a thing as "slant 45 radio"? Isn't polarization a characteristic of antenna and not of radio?
Shouldn't any dual polarization radio unit be compatible to either linear or slant 45 antenna?


texts: Connecting 2 ventilators to the same output?

texts: So i have an output of 5V 1A, and i want to connect 2, 5V 0.15A ventilators to the same output, and the question is - will there be enough voltage for both of them(because i have 1A output, and both of them would only need 0.30A)? Or do i still need 10 V?


texts:
How breakdown voltage of common base configuration is higher than that of common emitter configuration??

in common base, break down is more or less similar to PN junction breakdown.
please explain how breakdown occurs in common emitter configuration???
I read because of transistor amplification, common emitter Breakdown has less value than PN junction breakdown. more explanation needed to understand clearly.


texts: Do current / power monitoring ICs (e.g. INA219) allow frequent re-reading?

texts:
I'm looking at the datasheet for the Texas Instruments INA219 and on page 20 it shows a table for "Shunt ADC Resolution/Averaging", which describes the ADC resolution and averaging settings which can be applied, along with their conversion times.

I'm trying to work out how frequently I can re-read the power value computed by the sensor IC.

As an example, the 12-bit resolution single-sample option (bits: 0X11) has a listed conversion time of 532μs (which is actually listed in the electrical characteristics with a maximum of 586μs). There's then a minimum convert input low time of 4μs, and the time it takes to communicate via I2C (should be sub-microsecond if I'm using high-speed mode).

So, in conclusion, should I expect to achieve 1800 3000 actual sensor readings per second minimum in such a configuration? Or is this likely a more marketing-friendly rate?

Also, as a side note, I notice that configuration options 0X11 and 1000 both result in 12-bit resolution and single-sampling, with the same read rate, but with a difference in which ADCs are used - is there a reason to pick one option over the other?


texts: Help verifying my transfer function computation for Non-Inverting OpAmp circuit!

texts:
Attached is the work I have done to compute the transfer function of the circuit I designed..
I would like help verifying my work / correcting it and determine the phase... I haven't taken a circuits course in 2 years so I am embarrassingly rusty..
The goal is to compute the transfer function so I can relate the Input Voltage to the Output Voltage. This will help me understand how each component effects the system! Plus I really need the practice.
Highlighted in green is what I think its the transfer function for the OpAmp output voltage (Vx) with respect to the input voltage (Vin).. But I'm having quite a hard time trying to compute the rest of the circuit so i have a transfer function that relates Vout for Vin.
What I think may be happening is when the diode conducts, Vx = Vout, thus what is in green / yellow is the final answer?
Or does the Diode, smoothing capacitor, and bleed resistor play a roll here as well? (I imagine it does, but this is the hump i cannot get over).
If someone could please assist me in verifying this work, or providing me with the correct solution so i can correct it. That would be very much appreciate!!


texts: Does high frequency transformer design vary based on type of switch used for inverter

texts:
I'm going to design an SMPS, in which 120V High frequency AC will be step down to 48V AC high frequency (50KHz) using HF Transformer and then rectified.

I have done the calculation for HF transformer design(120V to 48V AC,50KHz). When I gave the design to manufacture, he told me that HF transformer design varies based on type of switch used for inverter in primary side. I would like to know whether that is true.


texts:
I have been working to create a digital scale for IOT project, using HX711 ADC.
The problem
Since it is crucial to have wifi connection, I use Raspberry Pi, to control the scale.
Everything works well, when wires between Raspberry and the HX711 stay in 20cm range, but problems gradually start to occur, when wires get longer than that. The measurements are much more off in case of 50cm wires and absolute garbage at 100cm.
Tried the same configuration on Arduino UNO, no problems there.
Possible causes
I am not sure, if the system doesn't work, because

I am using RaspberryPi with Linux based operating system, and that is not meant to controlling hardware.
I am using Python library for the HX711 Github link for the library

Or maybe it is both. My own experience regarding issues like this is somewhat limited, maybe somebody could point out an elegant solution around this problem (cost of the solution is pretty important factor as well)


texts:
I was reading this book which talks about behavior base robotics. Since it uses IC for programming at some point it uses a function called startprocess(). After looking through the web I could not find how this function could translate in plain C. Or how to implement a simple two behavior in C

So here is two simple behavior, with it's arbitration system. I actually understand very well how this can work. The on thing that does not make sense is how would I start the behavior in C

//Cruise Behavior
int cru_trans = 0; //Translational rotation velocity
int cru_rot = 0; //Rotational velocity
int cru_act = 0; //Cruise active flag
int cru_def_vel = 100; //Default speed

void cruise(void){
    while(1){
        cru_act =1; //Cruise Always wants control
        cru_trans = cru_def_vel; //Standard Velocity
        cru_rot = 0; //Don't rotate
    }
}

int av_trans = 0; //avoid translational velocity
int av_rot = 0; // avoid rotational velocity
int av_act = 0; // avoid active flag
int av_def_trans = 100; // avoid default translational velocity
int av_def_rot = 50; //avoid default rotational velocity

void avoid(void){
    int ir_hit = 0; //Local variable for obstacle detection

    while(1){
        ir_hit = ir_detect(); //ir_detect returns which ir sensor sees something
        if(ir_hit == 0){ //No detection
            av_act = 0;
        }
        else if(ir_hit == 3){ //Detection Both side
            av_act = 1;
            av_rot = av_def_rot; //Arbitrary rotate left
            av_trans = 0;
        }
        else{
            av_act = 1; //Avoid wants control
            av_trans = 0; //Don't move forward
            av_rot = av_def_rot; //Rotate away
        }
    }
}

int mot_trans = 0;
int mot_rot = 0;

void motors(){
    while(1){
        drive(mot_trans,mot_rot);
    }

void arbitrate(){
    while(1){
        if(av_act){
            mot_trans = av_trans;
            mot_rot = av_rot;
        }
        else if(cru_act){
            mot_trans = cru_trans;
            mot_rot = cru_rot;
        }
        else{
            mot_trans = 0;
            mot_rot = 0;
        }
    }
}

void main(){
    start_process(avoid());
    start_process(cruise());
    start_process(motors());
    start_process(arbitrate());
}


texts: What happens if a dependent current source does not dissipate/generate energy?

texts:
If that dependent current source doesn't generate/dissipate energy (Power=0) in the given circuit, How do we approach that kind of problems?. I know independent current sources behave like open switches when power upon them are zero (P=0). So should i assume that dependent current sources will behave like open switch as well?
Also another thing that confuses me;
P=V.I
Therefore,
V or I has to be 0 but how do we decide whether Voltage Drop on current source is 0 or the current that is created by the current source is 0.


texts:
I bought a blue pill that I tried to program using STLink on CubeMX IDE.

I got this:

  Warn : UNEXPECTED idcode: 0x2ba01477
      Error: expected 1 of 1: 0x1ba01477

I checked on the internet and I found that it's a fake one.  I got the idea to edit the
stm32f1.cfg file so I changed

  set _CPUTAPID 0x2ba01477

to

  set _CPUTAPID 0x1ba01477

It worked perfectly the first time, but after a couple of seconds the green LED turned on and now the problem I have is:

  Error: init mode failed (unable to connect to the target)

Any help please? I can't afford another blue pill for the moment and I really need it for my studies.


texts: leaking AC current into household electronics

texts:
I have a problem i recently discovered. My home has AC current leaking from all electronics i use. my laptop power supply, my 3d printer, etc..

This was not a major issue until i built my 3d printer. the inductive bed sensor uses 12v directly from the power supply. the leaked current is messing with the sensor readings on the RAMPS board.

Anyway, is there a way I can get rid of AC current leaking into my power supply output ? (12v)

I tested the leakage with a mains voltage live wire tester. all lines (+ve and -ve) were hot. I switch the power supply to UPS only power, and the leakage is gone, so its not a power supply issue i guess. besides, its happening to everything in the house.

I need to mention that i live in a country where there is no earth.


texts: My game controller's charging port broke. Now I'm trying to make it run on replaceable batteries, but I'm having some problems

texts:
The controller needs 3.7 volts and 250 mAh. I have Kirkland Signature AA batteries. Each are 1.5 volts. Not sure the mAh or whatever that is. How could I raise the voltage from 3 (2 AA batteries) to 3.7, or lower from 4.5 (3 AA batteries) to 3.7? How can I get the mAh right? Is there some other super simple option I'm missing. I could probably buy another charging port or something, but the pins are so small so that would be too hard to connect.
Edit: Found a solution to the voltage problem I believe. Making a voltage divider with one resistor being 8 ohms, and the other being 37 ohms. Still got the mAh thing though.


texts:
Often debouncing circuits are done like this :

simulate this circuit – Schematic created using CircuitLab

In this case, when switch is closed, C1 discharges in its internal series resistance, so discharge is very quick. If there is some rebounds and we suppose C1 internal resistance << R1, capacitor discharge time << capacitor charge time. Consequently, during rebounds when closing switch, response time will be very quick. I assume this configuration is useful when  we a quick falling edge detection is required.

But, is this configuration safe for C1 lifetime?


texts: Implementing 4-to-16 decoder using 3-to-8 and 2-to-4

texts:
This is digital logic question. I think it's alright to post it here.

I'm trying to implement a 4 to 16 decoder using 2 to 4 decoder and 3 to 8 decoder.

What I did, I used 2x of 2-to-4 decoder and 1x 3-to-8 decoder. But I think there is a mistake in the 3-to-8 part.  I hope you could point me out to it.

Here is what I did,

Note that I couldn't continue writing the full table.


texts: 0-5V supply to control brightness of BWTek spectroscopy light source

texts:
I recently installed a BWTek BPS101 tungsten halogen light source and would like to take advantage of the builtin support for manipulating the operating current (changing the brightness) via an external power supply.

The manual says gives a pinout where pin 1 is ground and pin 2 is "Analog control input". 0 VDC corresponds to minimum power output and 5 VDC corresponds to maximum power output. The pinout doesn't provide a 5 VDC rail at all. It also says:

  You must make sure that the input current from the Power Supply matches the impedance of the light source. If they do not match, a proper Current to Voltage curve will not be obtainable.

The manual specifies the device's input resistance is 3.5 kOhms.

How do I design a circuit that won't fry this expensive instrument but will let me variably control the power of the light source?


texts: "Normally closed" switch with NPN transistors

texts: Is it possible to have "Normally closed" switch with NPN transistor when the voltage at the base is 0V? So far I only managed to achieve this result with NPN transistor when the base is HIGH. When the base is LOW it's "open" and outputting 1.8V as in provided image below and this is not what I'm expecting. Thanks!


texts: What happens to the load when a bridge rectifier is in over-voltage condition?

texts:
Please read carefully, this may or may not be trivial:

Your  bridge rectifier (Schottky diode based) is rated for 60 Volts Maximum Peak and the AC wave peaks at 65V for a short period of time.

What would happen to the transformer and what would the load see?

It seems to me that the reverse polarity diodes would act like two TVS diodes and "clamp" the source thereby somewhat protecting the load. Or would some other result occur?

(assume the silicon and packaging can dissipate the heat and temperature is not an issue).


texts: Current split on sn754410 chip and electromagnets?

texts:
Here is the schematic, except this uses the L293d

I wanted to better understand how does the current split (if it does) between two of these IC chips wired as diagrammed with 2 electromagnets on each IC (total of 4)?
If my external power supply is 3.0V ~0.85A.

Also, how can I adequately measure current between an electromagnet that's hooked up to an h-bridge driver? I notice the current at each of the motor pins (3, 6, 14, 10) differ when I do.


texts:
Hi, I have been asked to estimate the half-power cutoff frequency of a first order filter that gave this response to a step input.

The problem I am having is I have only ever been given examples with the response in frequency , with db/frequency, here it is volts/sec which has completely stumped me. How can I convert this to a frequency response to allow me to determine the cutoff frequency?


texts: Is there a way of powering an incandescent light bulb without AC mains?

texts:
I'm looking to power a light bulb for a greenhouse project, but I do not have the option of using the AC mains (for safety reasons). Is there a way to power it on using a lower voltage? I have a solid state relay and a bulb and fixture lying around. Should I look into amplifiers?

I'm using the bulb to provide heat to the greenhouse (the greenhouse is very small) and I'm looking to control it using an Arduino.


texts: Automotive filter against voltage spikes

texts:
I am building a electric vehicle relay controller. Which controls the High voltage relays among other things. I have built an automotive power supply circuit with strong inspiration from this article: https://www.analog.com/en/analog-dialogue/articles/comprehensive-power-supply-system-designs-for-harsh-automotive-environments.html
(using both the filter circuit and power circuit)
I still have problems with voltage spikes from relays outside my PCB, the HV-relays and vacuum pump relay and many more. I am aware of the solution of putting diodes across relays. And that works as a specific solution. But I would like to install the control board in other cars as well without needing to put diodes across all relays in every car I do this on.
I have tried everything. As it says in the article I have used TVS diodes across the input voltage. And I thought that would solve it, but as soon as I remove the diodes(different diodes) over one of the many relays the problem appears again. If someone could point me in the right direction of what more I could try I would be very grateful.


texts: LED control via USB to Parallel Port in Linux

texts:
I have USB to 25pin Logilink cable. I connect it with computer with Linux and get a port in /dev/usb/lp0. When I connect LED with pin 1 and 25 as +/- of LED it lights. Now I move + pin of LED to pin2 (data0) pin. I want to send byte so that if can switch on it. I wrote a simple program where I use outb(0xff,port) being port 0x378. Program compiles and runs first time but LED does not light. Next time program even does not execute and seems to be halted.

Can I find some C program in Linux to do that?


texts: Programming a bare ATSAMD21E18A, no external oscillator

texts:
EDIT: I got this working, seems that the uC is sensitive to bypass caps. I had caps on my solderless breadboard and decided to solder on some surface caps right at the pins on the breakout board. That seemed to do the trick.
I have a standalone ATSAMD21E18A on a breakout board that I'm trying to flash. I've followed the steps here, to burn the bootloader. It looks like it took just fine. Then, it seems like I can flash the standalone chip over the jlink interface but then it just does nothing.
I've successfully done this process with a Trinket M0 and I'm using PlatformIO to do step-through debugging using jlink. I've compared the fuses of each and I had a hunch that the standalone chip isn't using the internal oscillator for some reason. Am I wrong? How can I confirm that the internal oscillator is being used?
I burn the Trinket M0 bootloader on both the bare ATSAMD21E18A and Trinket M0. Trinket works, the bare ATSAMD21E18A doesn't. I've tried this now on 3 different ATSAMD21E18As with the same result. What am I missing?


texts: What is the maximum transmission power of a 4G/5G phone with multiple antennas?

texts:
As we know, a user equipment (UE) can transmit its traffic with the power up to 23dbm. However, there is few materials mentions the maximum power a UE can apply if it has multiple antennas.
In this paper: https://www.researchgate.net/publication/344886461_Joint_Power_and_Resource_Block_Allocation_for_Mixed-Numerology-Based_5G_Downlink_Under_Imperfect_CSI
It seems they assume different antennas have their own maximum power constraint; i.e., each antenna can transmit its data with the power up to the maximum value (e.g., 23dbm). Nevertheless, this indicates that if more antennas are used, more power will be required.
Is it the truth? Or in fact all the antennas share the maximum transmission power (the sum of the transmission power of all antenna should be less than the limit)?


texts:
How can we use potentiometer to regulate voltage form o-5v?

That is, if we rotate the potentiometer it will give some voltage variation as output.
If there any circuit available please let me know the function of that circuit.


texts:
I am trying to run a formerly cordless Dremel with a 12V supply. I know that the dremel runs off of a 4.8V battery, so I would like to see if I can run the motor with 12V PWM without damaging it. However, I haven't been able to find any data for this motor.

The motor is 28.5 mm (1 1/8") in diameter. The front has the word "Johnson" and the symbol of Johnson Electric. There is text on the motor reads:

2610916361
32057
3t2903
-----

However, I can't find any motors on their site that match. Any help in either finding a datasheet or safely testing the voltage is appreciated.


texts: AC motor speed controller (via frequency)

texts:
I'm building this circuit from an old schematic for a stroboscope (spins a disk with patterns on it and strobes a light based on input frequency). I've already built the frequency divider (it is extremely cool ripple counter with clock chopper feedback that calculates a 1/(2^n) equation), and the input strobe circuit (converts an audio signal to a square wave). I'm stuck on the motor circuit.

I believe it is controlling the speed of a 50V AC motor via frequency because the input on the lower left NPN is a 50% duty cycle square wave that varies from 30-90 Hz.

There's 50V DC supply on top there, and the input signal is 5V (through the 4K7 on the lower left). The transistors stacked below the 50V are all listed as generic high Vce devices, and the 71963-1 devices are just generic NPNs. I have no info on the motor, other than I assume it is a two pole 50V AC motor.

Three things about the circuit confuse me.

1) Why the need for the NPN with 1K tied to 50V on top?

2) I understand the need for a Darlington array to drive the high voltage and current, but why the PNP on the bottom? (Is it to pull to ground faster b/c of the current in the coils?)

3) Why would the cap values into the windings be so different (100n & 5u6)? Is it something specific to the SKU of motors they had made for the device, or is there some other standard trick here that I don't get? (note: the text on the lower cap says 5.6 NP, not NF, I assume that means non-polarized?)

Thanks in advance, I know it's a lot of Q's but searching for "basic analog circuit analysis" on google brings up much crap.


texts:
I am new to analog electronics and I have been hearing this word from my seniors they always talk about Rail-Rail supply while working on some amplifiers and Opamp,also while calculating and designing a suitable pull-up network ,can anyone please explain what are significance of rail-rail supply.
All I know that is has to do something with the +ve supply  and -ve supply,Can we just ground the other end ,Why do we need this rail like structure?


texts:
I am sampling a video signal from a linear imager. I noticed when the illumination is just at the intensity when the ADC increases by another MSB bit at the output, the noise occurs. That is, when ADC transitions from 0111 to 1000, 01111 to 10000 and so on. It happens at every transition. At least, this is how it appears to me. What could be the source of such noise?

I suspect, this happens somewhere on the digital side of the circuit. Here's the quantitative profile of the image intensity at the line20:

Here's the sample clock signal before and after the gate buffer:

yellow: 0-3.3V

blue:0-5V

EDIT:
In short: the problem was with timing that is discussed in this post and the bad grounding that is discussed here


texts: Antenna concept, is it a passive device but how about gain?

texts:
Cisco antenna explanation

Here it says that antenna is passive device which doesn't offer any  added power to the signal. But at same time it says that antenna is responsible for increasing the amount of energy to a radio frequency (RF) signal.

So I don't get aren't they opposite things? How can it be a passive device and increase the amount of energy to a RF signal?


texts:
I have 3 separate grounds in my project:

AGND - Analog ground is very quiet, very small relatively smooth currents
PGND - Power ground used for power bypass caps and power supply related circuitry is less quiet
DGND - Dirty ground for digtal, led drivers, relays and things that cause horrible fast transient spikes and high current spikes

These grounds run over separate traces / wires back to a "star" on the power supply board.

Q: If I make a ground plane area that is DGND (the "dirty" ground), is that more or less likely to emit noise that could be picked up by surrounding circuitry as opposed to making the DGND circuitry regular traces and using another ground like PGND for the ground plane?

Generally we think of ground as being a low noise low impedance path. But if it's actually really noisy like a "dirty" ground that can see enough current to cause 100 mV spikes relative to a regular "quiet" ground, is that suitable for a ground plane or will putting noise into a big plane cause more harm than good?


texts: Automatically connect exposed pad to ground plane

texts:
Designing my first PCB. The switching IC in my DC/DC converter requires an exposed pad to be connected to ground to provide a low-resistance path. However, EAGLE wants to leave a clearance between my ground plane and the exposed pad:

Is there any way to remove that empty space? I have already tried

Setting DRC > Clearance > Same Signals > SMD and SMD to 0mil (nothing happens)
Inserting a rectangle on the top copper layer to cover the empty area (the clearance comes back when I reload the board file or press Ratsnest)

Thanks!


texts: Can I connect grounds of two different 9V batteries?

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I want to make a backup battery connector for my project so I can power it externally if the internal battery dies.

For this, I'm planning to use a SPDT switch with the pole connected to the circuit's power input and the throws connecter to both the batteries positive terminals. In this way, the grounds of both the circuits will be connected to the circuit's gnd input all the time.

Is this okay? When I'm powering it from battery one, battery two's ground will also be connected to the circuit's gnd. Won't current flow from one battery to another?

Should I use a DPDT switch to switch both positive and negative wires?

Thanks a ton.


texts: Cable connector order causing USB to break

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We have a system that's using nonstandard connectors (M12) to provide 24V power from one device to another, along with USB lines. Each system has ESD protection on its usb lines.

The issue is that when you plug in the cable, sometimes power and USB will make contact before ground. This causes lots of current to flow through the usb lines, breaking the ESD protection and the devices connected to the bus:

Is there anything we can do to fix this, other than changing the connectors (to be special purpose make first break last, or standard usb)?


texts: How do I choose the right replacement fuse for my multimeter?

texts: I have a BK Precision 2709B Multimeter. I managed to blow the uA fuse (500mA/500V fast blow ceramic) on it. Is it an ok to replace this fuse with a 500mA/1kV fast blow ceramic fuse? What impact would this have?


texts: Anyway to Visualize Current without an Oscilloscope with that Function?

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Having only an ordinary oscilloscope that shows voltage, is there any way to modify the circuitry or do some intelligent guessing to get an idea of what the current wave form looks like?

In my case, I'm pulsing a coil with square voltage waves and I want to see the resulting current being caused by inductance and parasitic effects to get a sense of how well my coil is constructed and what exactly it's doing to the waveform.  I'm particularly interested in its behavior during discharge during the low portion of the square wave.


texts: Requesting Advice For Selecting And Sourcing A "Medium Torque" Motor

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For a prototype project I'm building, I need to select a motor. I'm not familiar with different types of motors, so I have been trying to do some research. However, most of the stuff I have been able to find has been about low-power motors (e.g. handheld devices, models, etc) motors or about high-power motors (e.g. car winches). I haven't been able to find much information (or sources) for medium-power ("human scale") motors and I've been getting confused by the different types (e.g. AC vs DC, series wound, permanent magnet, etc) and the different trade-offs for these within this power range.
Essentially, my key requirements are:

To pull a cable in (and let it out) against a force of up to around 2 kN at speeds of up to around 0.5 m/s.
Within that force range, the line speed should NOT vary with the applied force.
To control the direction (in/out), speed of the motor and the position of the cable with a computer.

The machine will be fixed in place, so it can be mains powered. The total distance the cable will move will only be a few meters. The machine can also be quite large, so the cable could be spooled from a drum/wheel with any radius up to about a max of 0.5 m (I was considering using a bicycle wheel). So the max torque needed of the motor would be something like 1 kNm (with a 0.5 m drum/wheel) to 200 Nm (with a 10 cm drum/wheel).
If anyone has an advice to offer on what type of motor would be suitable for this application and where (ideally in Europe) it could be sourced from, I would be most grateful.


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I am trying to make a 7 segment display that displays the symbol <, > or = depending if a > b or a=b or a < b by using the output of a comparator(7 outputs from the comparator according to the exercise). I can't figure out how a comparator gets 7 outputs when it only has 3?

EDIT: I am supposed to do this with a 2 bit 2 input comparator and 4bit 2 input comparator.


texts: What is a good Field-Effect Transistor Model?

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Hi guys I'm writing an electronics circuit simulator and I need a very simple and straightforward model for a field-effect transistor (as simple as the Ebers-Moll model for a BJT). I can use resistors, voltage sources, current sources, diodes, (I can also use a resistor with a very large resistance to measure the gate-source voltage).

What model would you suggest?


texts: How to calculate the voltage drop in this case?

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I started with the superposition principle.
For Vcc, Ib is open circuit and Eg is shorted. I got that the voltage drop due to Vcc is 10000/3 V.
For Ib, Eg is shorted as well as Vcc. Since Ib is dc then the inductor is also shorted, correct? I got that the voltage drop due to Ib is 1/3 V.  Is it right?
But I am not sure how to proceed about the Eg, how to calculate the equivalent voltage in this case?


texts: Does this prototype match the schematic?

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I'm following this project which shows how to make an OpenTherm Adapter for an Arduino. It includes this schematic:

Along with this simplistic PCB diagram:

I am now in the process of making my own version of this circuit on a prototype PCB board. This is my first time making anything more complex than a simple header wire circuit using an Arduino and has therefore posed a bit of a challenge. However, with the help of Fritzing, I have been able to prototype a board design:

I understand this is a messy design and has lots of room for optimisation, but my question is whether or not the design I have made matches the schematic in the first image above. I would really appreciate it if someone could look over my schematic and let me know.

Thank you in advance for you help.

P.S. Here is a link to where you can download the schematic file (.fzz)

EDIT

The circuit will be connected with a combination of excess solder and wires. Please bear this in mind where it may look like some tracks overlap. Feel free to download the file for clarification.


texts:
I bought a lab Psu device and I would like to use it to charge 1.2v batteries. However the manual says that it's not reverse voltage protected and it might get damaged.
After some research I found out there are some Mosfet modules or IdealDiodes that can protect against reverse voltage back to the PSU. Please see Figure 2, I'm not talking about reverse polarity.
As I am intending to use it to charge low voltage batteries 0-12v, can anybody offer me some help if it exist any module for this that you can connect in between the PSU and the battery? Or what would be the best transistor for this?

Thanks!


texts:
I'm looking for a simple short range metal detector.

I've looked everywhere and I can find only complex metal detectors circuits to find metal at several cms of distance, most over 60cm, they are an overkill for my purposes. What I want is a simple circuit to detect metal presence at no more than 1 cm of the search coil, I have an Attiny MCU available on the board where this should go, if that helps.

I was thinking into pulse the coil at some frequency, and measure the frequency at the other side of the coil. From what I've read, if I put a metal object near enough the inductance on the coil and the metal would make the frequency change at the receiver/measuring side. But i'm not sure how exactly implement that.


texts: Can I overvolt a motor when the current stays within the limits?

texts: I have a 12V 0.24A computer fan. When I supply it with the 12V, it drains something like 0.17A. Can I increase the voltage until the current reaches 0.24A or will it destroy the motor?