texts: How to identify footprint dimensions from datasheet to create my own footprint using KiCad

texts:
Can someone help me in identifying the component dimensions from this datasheet BD-datasheet

Actually, this datasheet is confusing for me. so someone please help me in identifying the dimensions and fill the following properties by extracting the data from the datasheet:

PAD pitch:
PAD horizontal size:
PAD vertical size:
Drill size:


texts: Confusion with "skip initial operating point solution" in LTspice

texts:
I'm trying to simulate the following boost converter to see Vout versus Vin:

In LTspice if I run the simulation for the first 250ms I obtain this plot where Vout < Vin:

But if I chose "skip initial operating point solution", I obtain the following plot where Vout > Vin:

These two are completely different. How is "skip initial operating point solution" changing the results?

I thought this option is for speeding up the simulation by skipping initial conditions like setting capacitor voltages and inductor currents to a value(?). But in this case it is also outputting totally different results.

What should be the general approach here when simulating circuits with or without this option?  I'm confused in which cases one should use this option and in which cases it should opted out for a realistic estimation. Because two outputs are completely different.


texts: What is the difference between the 3 circuits? (OP-AMP)

texts: I found different circuit diagrams, but I don't know what is the difference betwwen these ciruits? When which to use?


texts:
What size MOSFET do i need to drive about 6A 12V load? Will small TSOP6 package do the job without overheating?

I was thinking of using this one:
http://www.tme.eu/en/details/irlts6342trpbf/smd-n-channel-transistors/infineon-irf/
to PWM leds drawing about 6A, says that it can handle 8.3A but I'm worried about heating.


texts: Is 22AWG wire appropriate for 144-LED WS2812B strips?

texts:
There is a question on a 1m set of WS2812B LEDs at 144 LEDs/meter (60mA/LED at peak brightness) about what gauge wire is used. The seller replies that the wire is 22 AWG (linked above).

144 * 60mA = 8.6A

If this wire gauge chart is reasonably accurate, then it's not clear to me how a device that is designed to consume 8.6A at peak is appropriate for 22 AWG wire. Shouldn't it have 20AWG wire or better? What am I missing?


texts:
Are there any energy states of transistors?  i.e. zero energy, high energy etc.

If that is possible, can't we employ the configurations of transistors such as storing memory as energy sources? That is, can't we create energy from memories?


texts: High Voltage (3,000V) Capacitor Charging Circuit Needed

texts: I need help in designing a capacitor-charging circuit that will accomplish the following: charge a 3,000V/200uF capacitor from a 37V battery. The desired charge time is 5 seconds. The battery is a 329Wh size with >80C discharge capability. The capacitor will not be connected to a load on charging. I would also like to know what the approx. weight of the transformer might be and also, if I wanted to charge multiple capacitors of the same size in parallel, would I need multiple separate charging circuits or could some portion of the first circuit be used for the others (there is only one battery). Thank you for the help!


texts: AVR: Why doesn't my if statement yield TRUE?

texts:
int i=0;
DDRD = 0xff;
PORTC = 0xff;
while (1)
{
    if(PINC5 == 1)
    {...}

I have been trying to figure out why the comparison of PC5 pin of PORTC with 1 yields False everytime. I have activated the "pull up" resistor for every pins of Port C. But still, when I compare the PC5 to 1, I don't get the expected result.

I know the proper way is to do the comparison using the bit-masking.

if((PORTC &(1<<PORTC5))==0).

But I can't figure out why the code presented above doesn't work.

I feel like I am missing some fundamentals in bit-wise operators but can't figure out what exactly. Thank you!!

The datasheet of Atmega 328P says the following:

  All registers and bit references in this section are written in general form. A lower case “x” represents
  the numbering letter for the port, and a lower case “n” represents the bit number. However,
  when using the register or bit defines in a program, the precise form must be used. For example,
  PORTB3 for bit no. 3 in Port B, here documented generally as PORTxn.


texts:
I'd like to build a project where I'm essentially controlling analog signal generation in the audio range from a microcontroller. In other words, an analog synth with digital control. I'm at the stage where I've prototyped and tested most of the core circuits on a protoboard, using simply two batteries (+ some caps) for a -9V/+9V split power supply. Now that I'm about to move to layout a PCB, and adding the microcontroller, I'd like to also have a more robust PSU. The requirements are:

+12V, -12V outputs for the analog side (I can basically live anything between 9 to 15 volts, bipolar, actually)
+3.3V for the microcontroller
output current a few hundred mAs. I don't know the exact power requirements yet, but since I'm basically just doing signal processing, I don't expect there will be very much power needed.
Input from a DC wall wart. Wall wart because I'm not a professional, so I don't want to deal with mains voltage, DC simply because they're easier to find than AC wall warts
low noise in the audio range

I'm currently thinking of using something along the lines such as http://www.linear.com/product/LT3471, http://www.ti.com/product/tl497a or similar (suggestions are welcome), more or less just following the datasheet schematics to get the various voltages. I'm asking for general comments, is this a viable route to go, and some specific things:

will the switched-mode supplies produce problems with noise? Should I use a linear regulator after the inverters to reduce that noise, or will filter caps be enough?
the LT3471 would be nice since it has two outputs, but as I'm going to build this with a soldering iron, I suppose the leadless package would produce problems/be impossible to solder? Is there a similar part in an easier package? (I do have experience soldering SMD, and will need to do that anyway for the uC I've chosen to use, so SMD is okay)
what else should I know?
Is there an easier way that I'm just missing completely? :) I know about virtual grounds, but as far as I understand, splitting a +24V supply would also not be without its problems, when there's a reasonably complicated circuit to connect behind it. Also, 24V wall warts aren't necessarily easy to find, I'd probably need to cannibalize some laptop supply, etc.


texts: Finding the voltage across an inductor in a RLC circuit

texts:
Well, we have the following circuit:

And I need to find the voltage at the node \$\text{Y}_1\$.

My Work:

The input voltage and current relation is given by:

$$\frac{10}{s}=i_{in}(s)\cdot\frac{1}{\frac{1}{100+s76\cdot10^{-3}}+\frac{1}{100+\frac{1}{s6.8\cdot10^{-6}}}}\tag1$$

The current trough the resistor \$\text{R}_1\$ and inductor is given by:

$$i_L(s)=\frac{100+\frac{1}{s6.8\cdot10^{-6}}}{100+\frac{1}{s6.8\cdot10^{-6}}+100+s76\cdot10^{-3}}\cdot i_{in}(s)\tag2$$

And the voltage at the node \$Y_1\$ is than given by:

$$V_{Y_1}=s\cdot76\cdot10^{-3}\cdot i_L(s)\tag3$$

If I plot the solution I get:

  Question: Is this true?


texts:
Alright so there is a question that I need to ask. I am designing a PCB and I plan to include a ISP header for programming. Now one of the programming pins (PB3 - MOSI) is connected to a push button which I take input from. According to the application note (AVR042) I need to connect a 330ohm resistor between the button and the pin. I wanted to ask if it will cause any problem with the button input or not.
Also, is my reset connected correctly?

EDIT: The labels are not correctly showing up in EAGLE, my pin config is as follows:

PB3- MOSI

PB4- MISO

PB5 - SCK

PC6 - RESET

Also, the jumper JP_SPST connects to the buttons.


texts:
I have simulated the following circuit and have trouble with it.

Why are the input and output currents are not equal?
Is this problem from me or with SPICE?


texts: LTSpice: How to start the step of a voltage source at a different time in the transient simulation than t=0s?

texts:
If I have a complex circuit where things occur at different times instead of starting as soon as the simulation starts (t=0s), how do I setup those things to occur at different times in the simulation.

For example if I have a voltage source that should start it's step at t=1s, what can I do in LTSpice to ensure it's simulated this way?


texts: Reduce voltage to many lower output with resistors

texts:
I have a stable dc 12 volt input 2 Amps and i want to make 6 different exports out of it like a power suply.

I would like to make the six reduced outputs out of it :
12v as i get it from the input,9v,6v,5v,3v and 1.5v

I also like to use some easy and not complicated way such as resistors since my input is stable, so if i want to make the 12v into 9v out in the first output it would go something like 10ohm resistor as 1st and 30ohm resistor as second and my output will be 9v.

Then i just follow the procedure of the 2 resistors then to lower the 9v into 6v and so on to create the outputs i need.

If i am correct and it will work fine do i have to choose a type of specific resistors and ohms and does this affect my amps and volts or it doesnt matter at all since the Vs R1 and R2 and Vout maths are ok like the above ?
I can even use for example R1=1ohm and R2=3ohm to get the 9v output but does this makes any difference ?

Thank you in advance for any answer, help or advice on it


texts:
Above is the problem and my attempt to solve it. I am confused on how to proceed with Av calculation followed by how to get upper 3dB frequency.

Below is the solution provided by my instructor. I can't communicate with him now and I am confused with his approach. Please help me with this problem.


texts: Ratio between register and primary memory access?

texts:
I've been doing research to find how much faster register access is compared to primary memory. I find the ration is about 100 times faster, can that be correct, has it always been about that number of is this number increasing or decreasing?

I read that the microprocessor can access the register file twice every clock cycle and that a primary memory access can take 50 ns. A modern computer microprocessor's clock cycle is abt 4 GHz, which is about 10^6 cycles per second i.e. about 1 cycle per nanosecond (?)

Are my number appromimately correct or am I wrong by factor 10 somewhere?


texts:
So first at all this question isn't really about electrical engineering, but about electricity in general. However, I think this is the best place to ask, correct me if I’m wrong. Also I’d like to mention that my knowledge about electricity is very limited, especially my knowledge about alternating current.

While working in the garden today, I used an electrical mowing machine which is powered by standard 230 V AC. What I didn’t see, is that the extension cable I used, had a crack in the insulation wrap and some wires were exposed. However when I touched one of the exposed wires by accident, I felt a little “shock”, but it was way less hurtful than I would have expected from 230 volts.

My guess is, that I only touched one of the power wires, so the current tried to flow through my body to earth, but because I was wearing shoes with rubber soles I was insulated from earth very well and only a tiny amount of current was able to flow through me. Does this make any sense?

Also, if I had touched both power wires, or one power wire and the earth wire, I would have shortened the circuit with my hand and thus I would have gotten the “full load”, right?


texts:
I'm having some problems with an a LT1301 step up DC/DC converter. I'm using the circuit that appears on the datasheet to convert 5V to 12V, but I'm getting periodic spikes on the output when loading with a LED. The spikes are high, +- 5 Volts around the 12 V signal.

I don't understand why it doesn't behave like the datasheet says, if this is the same circuit.

Thanks in advance.

EDIT1:I haven't enough reputation to post more than 2 links, but the spike duration is around 60 ns


texts:
I am building a mono, internet enabled, WiFi radio and I have a problem.

I am running into what I believe may be a grounding issue.  When I turn the system on, I hear all kinds of noise coming from both my computer component and my WiFi dongle.

I know that the WiFi dongle is contributing to the noise because if I remove it, some of the noise is gone.
If, I use a completely different sound source, such as a battery powered MP3 player, I get very little noise.
I am thinking I may need a ground loop isolator, but curious as to whether anyone else has suggestions.

Here is a diagram of my circuit (sorry it's a bit crude)  NOTE: I am providing extra power to the USB hub because I do not believe the computer (it's a pogoplug) can output enough power over a single USB.

I am using Zaph's filter (as my receiver is a HiVi B3N)

And I am using a stereo to mono summing box here:

Finally, I am using this step-down transformer (LM2596S).

I found this question and think it may discuss a related problem, but I am not sure how I should proceed to fix my issue.

UPDATE:  I have tried the following layout with the raspberry pi and notice the same noise problem.  Also solved by using two seperate AC/DC adapters.


texts: When were 3-pin voltage regulators introduced?

texts: I can't seem to find this answer anywhere, i'll feel pretty dumb if someone is able to find it doing a quick google search. But.... I've had not luck. When were the first 3 pin voltage regulator ICs introduced?


texts: Why am I getting an error when setting the TRIS registers with PIC?

texts:
I am new to PIC programming, and I am trying to blink an LED using the PIC10F206. It has 4 I/O pins. I understand I must declare them as inputs or outputs, but the IDE I am using (MPLAB) keeps giving me an error when I declare the TRIS register. Attached is a picture.

The datasheet lists the TRIS GPIO register as having the name "TRISGPIO" but the compiler throws this error: "Unable to resolve identifier TRISGPIO".

Am I just getting the name of the TRIS register wrong? Attached is a picture of the TRIS GPIO register from the datasheet.

[EDIT]

Looks like it is a header file problem. When I highlight "xc.h", right click, and go to navigate -> go to definition, the xc.h file is pulled up but the code does not recognize my pic.h file which is where the header file for my chip is. See imagae for the xc.h screenshot.

I tried pointing to the directory in the compiler options but no luck. Any thoughts? Below is a picture of my compiler options


texts: What type of transformer should I use to convert 24VAC to 12VAC (or vice versa)?

texts:
I'm working on a project that combines a board from an electric organ with one of those cheap Chinese tube amps. The board requires +12V/-15V DC and the amp requires 12VAC.

I don't want to power the final product with two wall warts, because that would be fiddly and annoying.

The amp converts its 12VAC to ±30VAC internally, and my first thought was to power the amp off a 12VAC wall wart, then tap off the ±30 on the amp's board and power a 7812 and 7915 off of this (rectified first of course). But connecting them up causes a huge voltage drop, so it seems that this isn't going to work.

The current idea I'm working with is to power the whole project off a 24VAC wall wart, which will run the 7812/7915 combo fine, and also can step down at 2:1 to 12VAC for the amp.

My problem is that I can't find a 2:1 transformer suitable, but it seems impossible that such a thing doesn't exist. (The only 2:1 transformers I can find are huge, built to take 240V to 120V. This would work in principle but it would bring up the size/weight of the project by at least an order of magnitude which isn't ideal, to say the least.)

I bought some of these 78604-1C but they fry on 12VAC+ input. (The datasheet I have isn't forthcoming about a maximum voltage, which I am also confused about)

Is there a specific thing I should be searching for that will turn my 24VAC to 12VAC in a small package?
Or, is there some other way of solving this problem that explains why this type of transformer is so hard to find?


texts: SPI Loopback value received is half of transmitted value

texts:
I am testing SPI of my PIC24E512GU814 microcontroller. In order to test, I connected MOSI to MISO.

I wrote the following code for SPI initialization:

SPI3CON1 = 0;
SPI3CON1bits.CKE = 1;
SPI3CON1bits.SPRE = 7;
SPI3CON1bits.PPRE = 3;
SPI3CON1bits.MSTEN = 1;
SPI3STATbits.SPIEN = 1;

Then for transmitting/receiving the following code:

SPI3_ENABLE = 0;  //chip select
delayUs(1);
while (SPI3STATbits.SPITBF);
SPI3BUF = test;
while (!SPI3STATbits.SPIRBF)
{
      if (--timeout == 0)
      {
          debugOutput(0, "\r\nTimeout SPI 3\r\n");
      }
}
temp = SPI3BUF;
debugOutput(0, "\r\nValue read on SPI 3 Port:%d\r\n", temp);
SPI3_ENABLE = 1;

I am always getting half the value transmitted. For example if I transmit 54, I am reading 27 in the receive buffer. What can be the issue?

Modified the code to the following didn't help

delayUs(1);
//writeSPI(eSpiPort3, &test, sizeof(byte));
debugOutput(0, "\r\nWriting on SPI 3 Port:%d\r\n", test);
SPI3_ENABLE = 0;
while (SPI3STATbits.SPITBF);
SPI3BUF = test;
while (!SPI3STATbits.SPIRBF)
{
    if (--timeout == 0)
    {
        debugOutput(0, "\r\nTimeout SPI 3\r\n");
    }
}
temp = SPI3BUF;
SPI3_ENABLE = 1;
delayUs(1);
debugOutput(0, "\r\nValue read on SPI 3 Port:%d\r\n", temp);


texts: What is the best way to receive unsolicited response from GSM SIM900 in PIC18

texts:
I am using PIC18F2520 and trying to communicate with GSM SIM900. I am using UART interrupt to receive data from the GSM. I am saving each byte in rxData. Now most of the commands ends with response OK. But there are few commands which does not respond with OK like when we receive sms notification from GSM, GSM send following notification

 +CMTI: "SM",2

Now this response doesn't have any OK. How to receive data in this case. In my application I need to check for the received sms. I am using following code:

void rx_handler(void)
{
  rxData[index] = ReadUSART();

  if(<some condition>)    //condition to check for sms notification
  {
    rxFlag = 1;        //set flag to process it in main loop

  }
  index++;

PIR1bits.RCIF==0;

}

I am getting confused on how to check for the sms notification. Till now for other commands, I was setting condition for OK but this doesnt have any OK response. Please help.


texts:
I have a 12V led strip connected to a (cheap) 12V 5A switching mode supply.

The supply is connected to a remote control switch.

The supply does not have earth connection (only neutral and live)

The supply have an European plug ( Live and neutral can be switched by turning the plug 180°)

Since the remote control switch only cuts one connection (I think) if I connect the plug in a certain way the live or the neutral wire still reaches the power supply even if the "return path" is blocked.

In one of the 2 cases I noticed that if I touch the led strip some of the leds near the point that I touch turn on very dimly. I have no body->earth connection except for the body capacitance.

The questions:

Is this caused by me working as an antenna or by me working as a
capacitor for some low current AC signal on the output of the power supply?
Is this safe?
Is the power supply working properly?
Is the remote control switch working properly?


texts: Can I use SMD components or do I have to stick to through hole?

texts:
I work in a company which develops devices that need to withstand harsh environmental conditions, shocks, radiations, vibrations and whatever. Really, too many to count.

In one of those devices is a small existing board which basically takes RS-232 and RS-422 signals, runs them through some kind of protection, and transfers them forward.

Here are the two types of circuits:

RS-232 Protection

RS-422 Protection

World - the signal comes from the outside (or goes outside).

Internal - the signal connects internally to a connector in the device. All the internal signals are connected to some industrial board that acts as some controller.

In the board, the resistors are on one side and they are SMD. The diodes and capacitors are on the other side and are TH.
The diodes used in the RS-232 (and perhaps also RS-422) protection circuits are the 1N4744A.

To be honest, We're not sure what these protection circuits do, since it was designed long ago and the engineer that designed it left the company. Perhaps lightning protection? It would be great if you could tell me what those circuits could be for.

We want to produce more of these boards but the TH components being TH is giving us problems. I know this isn't a lot of information, but is it possible for you to know if the diodes and capacitors can be SMD instead of TH?


texts:
I usually understand well transistors circuits, but I just can't get to work with this one:

(Note the circuit is powered with +/- 12V)

It is supposed to be a schmitt trigger circuit, and I'm trying to get a square wave at output by putting a triangle wave at the input.
To do so, I'd like to detect when my triangle (oscillating from +12 to -12V) goes under -10V (negative trigger, output should go falling edge) and above +10V (positive trigger, output should go rising edge).

I could find an approximative formula for negative trigger, which is triggered when Q1 become cut-off:

$$
V_{N} = (Vcc-0.3)[\frac{R2}{R1+R2}-1]
$$

Now I'm trying to figure out what will be the formula for positive trigger, and what will be the voltage level at the output.

I'm also open to other circuits, if you mind something simpler (not using op amps, please).


texts: Solar variation tolerance for a solar panel

texts: How to estimate average variation of input solar radiation that would be tolerable for a given solar panel? On what parameters will it depend?


texts: Controlling RGB LED strip with transistor

texts:
So I am building 7 segment display with RGB LED strip. To power it, I was thinking of 1 transistor on the input and 3 on the outputs. And my question is: Could I be controlling all 3 of the from one pin (their bases would be connected + colour would be controlled by default controller)?
Hope it makes sense.
Thanks for any kind of help.


texts: Is the initial block in Verilog sythesizable?

texts:
I have come across a lot of posts which say that the initial block is not synthesizable in Verilog HDL. According to this appendix on synthesizable and non-synthesizable Verilog constructs (from the book Digital Logic Design Using Verilog by Taraate), the initial block is not synthesizable.
I prefer using a reset to initialize any content in memory blocks.
But my friends are doing a gaming project where they set the initial positions (values) of blocks using an initial keyword (we're using a Nexys 4 DDR FPGA). It worked.
I really don't know what to say because I thought it was not possible. Can you please explain this to me? I'm using Xilinx Vivado.


texts:
I'm trying to make a 50% oscillator with a Tout=10ms period. Instead, I get a 5.7ms period signal, and an off pulse (low level) of 150µs !

I chose POL=0 and RESET is grounded. From table 1 of the datasheet, I pick the 2nd line : DIVCODE=1, NDIV=8, R1=1Meg, R2=100K. Vdd=3.3V, Vdiv=0.29V => Vdiv/Vdd=0.088 (OK, should be 0.091). Then, I calculate Rreset = 50k/1.024ms*Tout/NDIV=61K, I pick 68K.

What's wrong ?


texts: Different ways to wire parallel-series battery pack

texts:
I need to wire up a battery pack using 1.5V AA cells in the form of a parallel-series configuration to achieve 4.5V and 9Ah (assuming a single cell gives 3Ah). The first configuration in the image is one way I've seen it recommended online: 3 cells in series to give 4.5V and 3Ah, then 3 of those in parallel to give 4.5V and 9Ah.

I'm wondering if the second diagram in the image also works? Start with 3 cells in parallel to give 1.5V and 9Ah, then wire 3 of those in series to give 4.5V and 9Ah? Is this correct? What's the advantages/disadvantages between the two options (assuming the 2nd works)?


texts: Is there any option to store AC voltage?

texts: Almost every power plants produce Alternating current. It is not necessary that entire energy that they produced are consumed in real time. Does they have any option to store excess energy?


texts:
I'd like some help in my attempt to phisically disable a wireless module and prevent it from emitting RF, or at least reduce them.

The module in question is part of a gaming console (Playstation 4) and works as a Wi-fi and BT transmitter/receiver.
Neither of them I actually need because I'm using a Lan cable for internet and a wired controller instead of the original wireless BT one.
On the other hand I'd like to reduce RF output from console to minimum because I'm affected by recurrent dermatitis due to proximity RF (iPad and wi-fi computers primarily) and would like not to give up using devices.

The chipset is a Marvell Avastar, soldered on the PCB, with three antenna traces leaving it, two of which lead to integrated Wi-fi antennas (in red), while the third and shorter trace (in blue) leads to a U.FL connector. This U.FL is connected to a cabled BT antenna.

I removed the BT antenna and actually I could notice the original wireless controller now works only within a shorter range (1-2 meters instead of previous 7-10). I don't even know if it means the RF output decreased at all or, as I read somewhere else, I ended up concentrating the output in a closer range, thus making it more harmful.

What could I do next to get a better and definitive result?
Unsoldering the module should be my last resort because I can't know if the console will keep working after that.
I read about:

Cutting the BT antenna trace as close to the module as possible
Connecting the antenna trace to ground (to dissipate the current  originated by the module?)
Any other options?

Would be really grateful if any expert could help me out, taking in mind I'm no engineer unfortunately.
Thanks a lot!


texts: I am currently learning digital logic and the textbook that I am using briefly mentions about two-hot decoders. I understand how a one-hot decoder works, and the textbook gives an example of a 4 to 16 decoder. However, how would something like a 4 to 5 two-hot decoder work? What do each of the 5 bits represent in this case?


texts: Audio power amplifier circuit explaination

texts:
This circuit:

My goal is to modify this circuit to operate in DC mode.

Got this circuit on the web, but there is some part of it that I still don't get how it operates.

T4/T5 is an adjustable current source, but I get lost down the path T1, T2, T6, T8 and also the impact of R11/R13. Changing values of C6 and C7 appear to change the gain which is quite surprising.

Is VR1 supposed to adjust the amplification gain ?


texts: What does it mean that a resistor has value of 56E?

texts:
I found on one schematic that has resistor with value 56E.

I don't know what does that mean.

Can you give me some information, please.


texts: Decode/Analyse the following UART signals

texts:
I have sent a 2 and a 9 using UART. The baud rate is 9600, there is no parity, and it has 8 data bits.

As we know 9 is represented as 1001 in binary. However, this is what I get from my UART signal:

A 2 is represented as 0010 but this is what I get from my UART signal:

I know I have to pay attention to the start bit, but other than that, I have a hard time seing the logic in this signal.

NOTE:

The signal works, but I just need help analysing it.


texts: Canceling Negative Voltage in a Microphone Amplifier Circuit

texts: I'm building a microphone amplifier circuit that will receive audible frequency inputs using an ADMP401 Mems Mic to a 741 op amp to a comparator to an FPGA.  The op amp requires negative voltage (+/- 3V to Vcc and Vee, respectively) to work but if I don't cancel it before it gets to the FPGA it will break it, apparently.  Will a rectifier diode do the job? If so, how do you decide which one to use?


texts: Why is peripheral clock frequency is different than oscillator frequency in PIC microcontrollers?

texts: Why does the peripheral clock(Fp) & cpu clock(Fcy) is half of the system clock in DSpic & 24F devices and quarter of it in DSpic30f & 8 bit PIC series. Does this have something to do with the number of stages in pipelining ?


texts: Why are pins in my ESP8266 getting damaged?

texts:
I designed a circuit and a PCB to connect a relay, a switch, a Modbus-to-serial and two sets of DS18B20 to a ESP8266, specifically ESP-12F, to be controlled via ESPhome. The power is provided by a AC-DC 5 V converter, followed by a low dropout linear regulator. The two sets of DS18B20 are about 3 m and 7 m long, each one using a different pin of the ESP8266.
See schematics and image of the board. R1 and R2 are around 4-4.3 kohm.

Since I made a mistake in the width of the traces, I provided wires for the GND and 3.3 V for some components.
While the board won't win any prize (I even inverted the order of the names of the ESP8266 pins), it was working fine, so I disconnected relay and switch for practical reasons and then I let it run for few hours. Then one string of temperature sensors stopped working.
I checked the connections, the pullup resistor, the continuity, and at the end I connected the sensor to a different pin of the ESP8266 (you can see it from the rear side). It worked again, but it failed not long afterwards. The same for the other set of temperature sensors.
Today I found by chance a study according to which all my DS18B20 are counterfeit, mostly from family D according to the link provided. I ordered new ones from Digikey.
However, according to the study I linked, fake chips are characterised by poor performances, they should not damage the pins of the ESP8266.
Are there are other issues with my circuit, besides the fake sensors, which could damage the pins of the ESP8266?


texts: How does an XOR phase difference detector behave when input frequencies are different?

texts: How does an XOR phase difference detector such as AD8302 behave when input frequencies are different? Does it give meaningful results when the frequencies are close but different? Is there a simple description of the phase detection error vs the difference in frequencies?


texts:
Currently I am working in a project on esp8266 and before getting into the project I started to read the library and in a section I found something which has no meaning to me. I need help on that

#ifdef NDEBUG
#define ESP_ERROR_CHECK(x) do {                                         \
    esp_err_t rc = (x);                                             \
    (void) sizeof(rc);   //why there is void return                                           \
} while(0);// why do-while loop with 0 as parameter
#else
#define ESP_ERROR_CHECK(x) do {                                         \
    esp_err_t rc = (x);                                             \
    if (rc != ESP_OK) {                                             \
        _esp_error_check_failed(rc, __FILE__, __LINE__,             \
                                __ASSERT_FUNC, #x);                 \
     }                                                               \
 } while(0);
#endif

Link to the head file (git hub)

Look forward to hear from you.


texts: Understanding the JTAG connector/adaptor attached to a smartphone

texts:
This stuff use a JTAG Box method but I don't understand where exactly wires is welted onto the smartphone circuit board.

Why they use the green adaptor over the board?

Source: http://sysforensics.org/2016/08/jtaging-mobile-phones/


texts: Snubber for Relay Contact Switching Resistive Load

texts:
I am working on a redesign of some circuit boards and am looking for a way to save space and potentially switch to surface mount parts. Some of the largest through hole parts in use are for an RC snubber across a relay contact like so

simulate this circuit – Schematic created using CircuitLab

The R2 is a resistive heater. There are some 8-30 foot wires between the switch and the load. The values of R1 and C1 were chosen before my time and persist because "don't fix what ain't broke". C1 is usually WIMA MKS4J031004C00KSSD and R1 is a standard 0.5W 5% resistor.

First, is an RC snubber appropriate for a circuit like this? Is there a better option? We have seen switches fail, with loads of much lower current and power than the 10 Ohm R2 shown, due to what appears to be carbon build up on the contacts. I would like to minimize these kinds of failures. I'm assuming that the carbon build up is caused by arcing of the contacts on open or close, but I'm not positive on this.

I would like to save space by changing R1 and C1 to equivalent surface mount parts. Is this possible or advisable given that C1 is rated for 400 VAC and 630 VDC?

Edit: Would, e.g., Kemet C2225C104KFRACAUTO be a suitable replacement for C1? It has a much higher DC voltage rating, but no AC rating. Are there other differences between film and ceramic capacitors that are relevant to this question that I should be aware of?


texts:
I have an ESP8266 that I've got connected to my arduino and communicating quite well with... Now I'm looking at options to run my conifig via battery, so need to find ways to shutdown the ESP8266.

Easiest way I have read is via the broken out CH_PD pin that is normally tied to 3.3v. However, further reading suggests that the TX/RX pins are 5v tolerant, the CH_PD is NOT.
So what would be the best way to power the CH_PD from a digital pin.

Options are Connect the Arduino digital pin to:

Voltage divider using resistors
Transistor switch?
small 100mA 3.3v regulator

I have no idea how much the CH_PD pin draws in mA... I assume very little.
I've used voltage dividers for signal, but not for constant ON applications like this would be.

Thoughts?

Thank you!


texts: Zero crossing detector: do I really need the 7W resistor?

texts:
I am trying to provide zero crossing detection to my controller. Using the schematic below, I managed to generate square wave signal, representing positive v/s negative half-period. The problem is that the resistor needs to be quite large :
CTR > 10%
Max diode current: 60ma.
I choose 30 ma working diode current. This yields 30ma * 230V = 6,9W for R1.

Quite the heater. Also, voltage rating above 400V is required. I realize that a transformer could be used to step down the mains voltage. However, those guys tend to be bulky and rather expensive. Any recomendations?

Edit:
I found some nice explanations onHardware deign and noise suppression on the site. stevenvh's answer looks especially promising on calculating the resistor value. So let's keep my question more general. What are the approaches - resistor, transformer, others. What characteristics are desired in the optocoupler? Is the chosen driving current (30mA) huge and unnecessary?


texts: Logic mosfet to switch 12v truck battery

texts:
I have a project I am trying to put together. My understanding is lacking though. I would really appreciate some help in helping me to understand what I am missing!

The circuit would be a a logic level mosfet that would be controlled by a microcontroller. So 3.3v at the gate. It will be set in between the battery and the ignition wiring harness. Essentially, i would be breaking one wire in the harness. Which connect to the steering column, and inserting the mosfet/circuit. so when the car is started if the correct pin is entered, then the mosfet would complete the wiring harness circuit and allow the 12v to pass through.

To my understanding so far, I would need a logic level mosfet that has a low level rds(on) that is applied when the VGS is 3.3 or lower.

If the above were true, and all I had to do was apply a small 3.3v from the MCU and that would allow 12v to pass through the drain/source??

It seems to simple! I feel like there is more and like I am missing something. Could and would someone either point me in the right direction or help break this down, correct me, and or explain to give me a better understanding. I would very much appreciate it!

EDIT: I am just trying to get a better understanding of how these things work! If I apply the MCU's limited 3.3v to the gate, then that would allow 12v to pass from drain to source?? Do I need to accommodate for anything else? Anything like leakage voltage, kickback voltage, etc?

Schematic:

https://goo.gl/photos/sKPDi2RFykXcvL8X7


texts: Why is the Vbe threshold of a Si NPN transistor 0.7V and not -0.7V?

texts:
In case of an n-p-n transistor, the Vbe is more like voltage across a p-n diode. Now, since the direction of electric field in the depletion-region is from n to p, how come the voltage across the p-n junction is +0.7 V and not -0.7V?

In other words, why n-region is not at a higher potential (as it should be from the diagram below)?


texts:
I'm trying to TWI communication between accelerometer FXOS8700 & micro-controller (nrf51) but I forgot to connect SA0 & SA1 line to micro-controller pin (or connection to GND) & all PCB printing completed. Both pin hanging, As per as datasheet:

  The slave addresses that may be assigned to the FXOS8700CQ part are 0x1C, 0x1D,0x1E, or 0x1F. The selection is made through the logic level of the SA1 and SA0 inputs. see Table 11 I2C slave address

Is there any way to resolve this problem using firmware?


texts: What happens when a ceramic bypass or decoupling capacitor goes bad?

texts:
What happens when a ceramic bypass capacitor fails? I am picking out parts and is wondering is it worth the extra few cents for rated capacitors?

Since generally most IC can function without a bypass, if a bypass cap fails there should be no problem right ? or when a ceramic bypass fails it forms a short circuit?


texts: why does signal attenuation caused by shadowing vary?

texts: Given a RF sender and a receiver, suppose the obstacles between them are fixed, both their material and dielectric properties, does the signal attenuation caused by their shadowing vary over time? If yes, what causes the variation? If not, why is it generally modeled as a random variable (e.g., log-normal) instead of a constant?


texts: Using PWR_OK to Activate an ATX Power Supply Automatically

texts:
Okay so, I have an ATX PSU that isn't connected to a motherboard, and I'm currently using the simple paper-clip trick to ground PS_On in order to trick the PSU into providing power when I need. However, doing this cleanly means wiring in a switch to do this, but my PSU already has its own switch on the back which I'd like to just use instead, rather than two separate switches. Now, I know that simply leaving PS_On grounded all the time isn't really safe to do if I have devices connected.

But then I found out about the PWR_OK signal, which is a +5V logical high signal that is triggered when the PSU considers itself ready (shortly after mains power is provided).

What I was thinking I could do is somehow wire up the PWR_OK, PS_On and a ground pin, such that when PWR_OK goes to high, PS_On is automatically grounded to activate the PSU automatically, but safely. I may still put a toggle switch in there for good measure, but I basically don't want to be able to ground PS_On without the PWR_OK signal.

I'd very much appreciate any help in describing how to do this. Please treat me as a relative novice for any answer; although I'm comfortable soldering things, mostly all I've done is things like creating my own splitter or adapter cables for computers and even then, only simple ones. It's been quite a while since I had to design a circuit, work out what resistors I need (and where) etc.


texts: Which kind of current driver should I use?

texts:
I need to drive a single led (Vf=3.3v, If=750mA) with a lipo cell (from 2.7 to 4v).

From what I've read, a buck driver will regulate the output current with a maximum output voltage of roughly Vin. This device will be suitable when the battery voltage is within 3.3v and 4v but not within 2.7v and 3.3v.

On the other hand, a boost driver will regulate the output current with a minimum output voltage of roughly Vin and a maximum which depends on the device (and some other stuffs). This device will be suitable  when the battery voltage is within 2.7v and 3.3v but not within when it is more than 3.3v.

None of the above solution works over the full input voltage range (2.7 to 4v).

Did I understood somehing wrong? What's the good solution?

Thanks

Julien


texts:
simulate this circuit – Schematic created using CircuitLab

I'm new to the world of mosfets and am trying to learn them better. Would this rectifier IC be safe for input voltages of 24V if Vgs on these fets is 20V?

Vdss is 30V and reverse on D1 and D2 is 30V.

With L1_2 at 24V and L1_1 at 0V it seems that Q1 Vgs would be a smoke-inducing 24V.


texts: ATMega16: Run a subroutine for a limited time

texts:
I have a problem on ATMega16. I can't seem to be able to make a subroutine run for a set amount of time. Here is the code:

void reverse(unsigned x){
    OCR0=x;                 //PWM 100%
    PORTB &= ~(1<<PB0);     //+ of Motor1   LOW
    PORTB |= (1<<PB1);      //- of Motor1   HIGH
    PORTB &= ~(1<<PB2);     //+ of Motor2   LOW
    PORTB |= (1<<PB4);      //- of Motor2   HIGH
}

so it's basically a motor control subroutine which applies a Fast PWM Signal using Port PB3. The input is the duty cycle. The 2 motors are controlled using a L298.

Now, I want to transform the code so that it takes for input the duty cycle AND a certain value for the time, such as 50ms.

I'm using Atmel Studio 6.0 on Windows XP.

Thank you in advance.


texts: Single terminal of voltage source attached to earth ground

texts:
This is a conceptual question I continue to struggle with as I have started studying electronics.

Say we have a battery, and one of its terminals is connected directly to a nice patch of highly conductive earth. Further assume that the potential of the battery is greater than that of Earth. Now I realize that this is not a closed circuit, but why wouldn't charge flow from the battery to the Earth? Doesn't there exist an electric potential which should cause the quantity of electrons in the battery to be drained or at least decreased to the point at which the electric potential between the Earth and the battery is the same? Isn't this the same principal that is behind electrostatic discharge (albeit this scenario is not implying such a large difference in potential?)

I have read every other answer here on electronics.stackexchange that references ground, and I am still not satisfied.


texts: what will happen at output current ? when two zener diode is in series?

texts:
"what will be the output current when we connect two zener diode in series "

simulate this circuit – Schematic created using CircuitLab

?


texts: STM8 alarm firing shortly after resetting time

texts:
I'm using an STM8L151F3 with the SPL, compiled with SDCC. I'm trying to generate an alarm interrupt after n seconds, then another after m seconds.
To do that, I reset the time to 0, then set the alarm time to n seconds. Wait for the interrupt, then reset time again and set alarm time to m seconds. I'm masking minutes/hours/dateweekday.
It works mostly as it's supposed to, except after resetting the time for the n seconds timer, an extra alarm interrupt is immediately generated. If I ignore that, the normally timed interrupt is generated.
I can solve this issue by comparing the RTC time to what the alarm was supposed to fire and ignore it if it doesn't match. But I would like to figure out why this is happening.
In this partial example, it would reset time, get an interrupt immediately, reset time, wait 10 seconds, get an interrupt, reset time, immediately get another interrupt, reset time, wait 10 seconds...
RTC_InitTypeDef   RTC_init_conf;
RTC_AlarmTypeDef  RTC_alarm_conf;
RTC_TimeTypeDef   RTC_time;

uint8_t alarm_status = 0;

static inline void init_rtc(void){
    RTC_DeInit();

    //use LSI clock
    CLK_RTCClockConfig(CLK_RTCCLKSource_LSI, CLK_RTCCLKDiv_1);

    CLK_PeripheralClockConfig(CLK_Peripheral_RTC, ENABLE);

    //AN3133 pg.20
    RTC_init_conf.RTC_HourFormat    = RTC_HourFormat_24;

    //38 kHz -> 1Hz RTC
    RTC_init_conf.RTC_AsynchPrediv  = 124;
    RTC_init_conf.RTC_SynchPrediv   = 303;

    RTC_Init(&RTC_init_conf);

    ///* reset time to 0 */
    RTC_TimeStructInit(&RTC_time);
    RTC_SetTime(RTC_Format_BIN, &RTC_time);

    /* only care about seconds, mask everything but it */
    RTC_alarm_conf.RTC_AlarmMask = RTC_AlarmMask_Minutes | RTC_AlarmMask_Hours | RTC_AlarmMask_DateWeekDay;

    RTC_alarm_conf.RTC_AlarmTime.RTC_Seconds = 5;

    /* enable alarm interrupt */
    RTC_ITConfig(RTC_IT_ALRA, ENABLE);

    RTC_AlarmCmd(DISABLE);
}

static inline void set_timer(void){
    RTC_AlarmCmd(DISABLE);

    /* reset time to 0 */
    RTC_TimeStructInit(&RTC_time);
    RTC_SetTime(RTC_Format_BIN, &RTC_time);

    //example times
    if(RTC_alarm_conf.RTC_AlarmTime.RTC_Seconds == 5){
        RTC_alarm_conf.RTC_AlarmTime.RTC_Seconds = 10;
    } else {
        RTC_alarm_conf.RTC_AlarmTime.RTC_Seconds = 5;
    }

    RTC_SetAlarm(RTC_Format_BIN, &RTC_alarm_conf);
    RTC_AlarmCmd(ENABLE);
}

/**
 * @brief RTC / CSS_LSE Interrupt routine.
 */
INTERRUPT_HANDLER(RTC_CSSLSE_IRQHandler,4) {
    /* alarm */
    if(RTC_GetITStatus(RTC_IT_ALRA)){
        RTC_ClearITPendingBit(RTC_IT_ALRA);

        alarm_status = 1;
    }
}

void main(void){
    init_stuff();
    init_rtc();

    while(1){
        wfi();

        if(alarm_status){
            alarm_status = 0;
            puts("alarm fired");
            set_alarm();
        }
    }
}


texts: Shifting a 2.7V digital signal to Arduino logical levels?

texts:
I'm pretty much a beginner in electronics and I'm currently working on a personal project, where I have a device, that is putting out a digital signal (square wave) that goes from 0V - 2.7V and I need to read that signal with my Arduino. That, unfortunatelly, isn't enough for the Arduino Mega 2560 since the minimum voltage to turn the digital pin high is at least 3V.

I've been doing some "research" and came across the MC14504B hex level shifter which seemed like the perfect solution for my problem. However... I'm having some trouble interpreting the datasheet...

TL;DR:
I need to level shift my 2.7V signal to at least 3V or more.

This is the logic diagram of the level shifter:

And this are the characteristics:

I'm not exactly sure how to interpret these numbers. I plan to use the TTL-CMOS mode.

From what I can tell, as long as input is considered 1 (high) my voltage at output will be ~5V if Vdd is 5V, which is perfect. Would a 3.3V Vdd be okay since Arduino needs at least 3V to turn a pin high?

Now to my real question... I don't get the Vcc and Vin (Vol, Voh) part.

From the table, we can see, that if Vcc is 5V and Vdd is 10V, the Vin will be a logical 0 if the voltage applied to the input is <= 0.8V, same goes for if Vcc is 5V and Vdd is 15V.

Now, from what I can tell, the input will be considered high if at least 2V or more is applied to the input when Vcc = 5V and Vdd = 10V/15V, but both the Voh and Vol change depending on the Vdd? What does this mean for my use case?

What if I use 5V for Vcc and Vdd both? What if I use 3.3V for Vcc and Vdd both? What if I use 3.3V for Vcc and 5V for Vdd and vice-versa. What happens in these scenarios? Could someone explain this in a very simple way please? I seem to be missing something here as my interpretation doesn't make sense to me.

Thank you!


texts:
I am working on dc motor speed control project in proteus and for the feedback i am using optical encoder.Dc motor speed is calculated by counting pulses from encoder.
But i wanted to know what is that reading which encoder shows just below it (as you can see in the image ). I am new to proteus and optical encoder.Did lot of google but coudn't find anything.Can anyone please help me ,my entire project is at halt.
Thank you !.


texts:
I'm going to buy a nRF24LU1+, which is an RF system with a built-in microcontroller. How do I find out what kind of hardware I need to program this specific chip?

The FAQ says:

  By pulling the PROG-pin high, the internal flash will be available on the SPI pins. It can be then be programmed as a standard SPI flash device, using any programmer that supports this.

Does this mean that I can program it completely from my laptop using only software?

It seems as though it can be programmed via USB, but I can't figure that out from the product specification.

  Supports firmware upgrade over USB


texts:
What are the differences in number of conductors between single phase and the 3 phase used in China as compared with what is used in the U.S.A.?
It's my understanding that 220v residential is strictly a single hot and a neutral. Is their line 220v on a single leg?  I've got some Chinese equipment to wire and it appears that have 1 leg hot in their equipment while the other leg on the 220v breaker is tied to the neutral.


texts: Which is more robust against temperature cycles, solder or wire wrap?

texts:
When connecting a bunch of components in something that will be subject to repeated heating and cooling, are soldered joints likely to be more or less robust than wire wrap?
Intuitively, it feels like wire wrap should be more resilient, but I'm not certain of that conclusion, and a poster here suggests otherwise: https://www.diyaudio.com/forums/tubes-valves/287205-vacuum-tubes-wire-wrap.html

However, after much experimentation, it became clear that wire wrap was only good for the short term, by itself. If the piece of built-stuff flexed much, then eventually oxidation would set in and make some one of the hidden dozens-to-hundreds of connections vexingly noisy. And never when debugging.

Is that correct, or is wire wrap likely to be more robust if done better? Or are there other factors to consider?


texts: Can I use a current divider to protect my IC?

texts:
I designed an oscillator circuit using a TLC555 timer IC to create a 2 second pulse, which is used to drive a 12V 6W solenoid via a relay. Both the IC and the solenoid are run off of 12V, but every time I tried to hook them up to the same voltage rails, the IC kept frying.

My guess is that the solenoid was trying to somehow draw power through the IC, thus burning it out. I've been using separate power supplies for the IC and the solenoid to prevent this, but I've also had problems with inrush current burning out the IC.

Ideally I'd like to power both devices using the same power supply, a 12V 54W DC wall plug which seems to have good voltage regulation. What would be the best way to ensure the IC doesn't get destroyed by the draw from the solenoid?

I've included an image of my circuit; the solenoid would ideally be placed between the Oscillating_Output_(GND) and the +12V rail

EDIT: I've constructed this circuit on a protoboard and it's currently running the solenoid as part of a test fixture for some mechanical pressure gauges.

EDIT 2: added an image of the physical circuit as requested. One set of orange and black wires connect the solenoid to a 12V power supply through the relay switch, and the other set connect the power and ground rails for the oscillator circuit to a 13.8V power supply. The 12V supply seems to have much better voltage regulation than the 13.8V.


texts: Can anyone shed some light on the naming conventions used by Texas Instruments manuals/guides/documents. For example slaa490, slau337. Is there a pattern hidden? Anyway to tell, just by looking at the name of the file, what product family it refers to?


texts: Glitch in AC sine wave interfering with phase cut dimming

texts:
My company installs ZigBee-based phase cut dimmers for bulbs and LEDs (those which support phase cut dimming). Recently, we encountered a site where we faced a flicker issue. The light is slightly flickering. When the same set of LED driver + LED is being tested at our test lab, everything is working fine. This issue seems very site specific.

Site details - Some active construction is still happening at the site. Machinery like stone cutters, drill machines are being used on a continuous basis. It's also possible that the site is being powered by a generator set and not connected to grid at all (I am not sure of this part yet).

Here is the site waveform:

I noticed a repetitive glitch in the AC waveform which could be a reason behind the flicker issue.

AC waveform as seen at our test lab:

This one looks different from the site waveform.

What is causing this distortion at the site? Is there a way I can correct it so that dimmers don't cause any flicker?


texts: In the picture is a Photovoltaic mosfet driver. So I understand that the JFET is used to discharge the MOSFET gate to source capacitance to decrease its turn of time. Whats the function of the 2M resistor ?, they dont say how its calculated. If its a bleeder resistor then shouldnt it be connected from gate to source like below?


texts:
I don't understand this circuit diagram here, but I'm sure that you can help me out.
I'll explain what I have figured out so far.

EDIT: It's a metronome circuit. Sorry for being unclear about that.

In every circuit, current tries to connect "ground" (-) and "+9 VOLTS" in this situation.
From the top down, 9 volts of current is waiting at the emitter side of Q2 (transistor). I'll get back to that.
On the left, the voltage is tuned down a bit by the R1 , then after it is a variable resistor (R2).

I am lost here. I know that R2 controls how fast C1 charges, and I know that at a certain point C1 will trigger Q1 and Q2 to release the 9 volts (see 2). This 9 volt burst creates the clicking sound.

What I am confused about is:

Why does C1 need to be directly connected to the speaker?
Doesn't some of the current from R2 go to Q1?
How does the capacitor discharge? I imagine that the capacitor will slowly charge up to a point, then let it out (presumably to Q1). When does it let out? Why does it stop it's "charging" routine to discharge?
Doesn't Q1's base run straight to ground? Why is it going to Q2?


texts: Would plugging a 1M resistor into the outlet be bad?

texts:
Other then touching the leads and getting shocked, if I plug a 1M, 0.5W resistor into the 120V outlet, would it be bad?

I calculated that \$\frac{120 V}{1 M\Omega} = 0.12 mA\$, which shouldn't do anything bad if only 0.12 mA is going through, but I don't know if AC is different or something.


texts: How do I increase the output voltage of a simple electro magnet generator

texts:
I think I know the answer to this already but I can't seem to find this on Google. The keywords are all far too ambiguous apparently.

I want to create a electrical flow with a magnet passing through a cylinder wrapped with copper wire. Pretty basic. I want to increase the voltage output.

My theory is that if I wound the copper tighter, decreased the width between them and increase the copper on the cylinder that I will get a higher voltage. I haven't tried it yet because I haven't bought the equipment. I am trying to plan it all out before I purchase anything. Is my assumption correct?


texts: Step voltage up or step voltage down when using batteries?

texts:
When using batteries to drive a load via a voltage regulator, is it better to step the voltage up from two batteries in parallel, or step the voltage down from two batteries in series? If there is no absolute answer, is there a general rule (or set of rules) for deciding which is best for a particular situation?

Are there any interesting cases where a particular circuit type bucks the trend? (pun not intended)


texts: How to correctly configure AD9951 for 10Vp-p, 100Mhz sinusoidal waveform

texts:
I am trying to build a function generator for sinusoidal waveform with frequencies ranging from 1 Khz to 100 Mhz with amplitude of about 4 Vp-p to 10 Vp-p. I have been looking at AD9951 DDS that takes 400 Mhz clock input and provides a maximum output sinewave of 100 Mhz. The IC is powered by 1.8V and takes 3.3V only for DVDD_I/O (pin 43). The datasheet is not detailed enough to touch upon a few point I need clarification with.

I am looking at a 3.3V, 400 Mhz oscillator (SG3225VAN 400.000000M-KEGA3). The OSC and complementary_OSC (pins 9 and 8) on AD9951 takes 1.8V, is it safe to use a voltage divider at the output of the 400 Mhz oscillator to bring down peak-to-peak voltage to about 1.8V. So using 220R and 68R brings the voltage down to 0.78Vpeak (0.78 x 2 = 1.56Vp-p). Is this approach correct or is there a better way to do this?
Since AD9951 powers up at 1.8V, I assume, the DAC (pins 20,21) would also output close to 1.8V?
As I need about 10Vp-p, how to efficiently amplify the ~1.8V DAC signal to 10Vp-p? I have been looking at RF transformers and dedicated ICs such as Mav-11+ which unfortunately cannot be shipped to Australia. Can I get a recommendation on how I can effectively amplify the sinusoidal signal at high frequency of 100 - 200 Mhz?

Edit
The load is going to be simple electrical circuits like opamp analysis, transistor biasing and also providing a signal to biosensors and changed the maximum generated frequency to 100 Mhz.


texts: Gerber Viewer With Good Measurement / Distance Tools?

texts:
I'm trying to measure some trace widths using Camtastic in Altium.  I have to say, I really find Camtastic very finnicky when I try to zoom and pan.  The measure distance function (which I am trying to use here to capture trace widths for an RF system) I've never really liked.

I'm coming from a reasonable amount of skill with Solidworks.

Could someone recommend an alternative Gerber viewer (doesn't have to be free), that is not so finnicky?

I've used GERBV last time I was doing my Gerber-trace-ninja-fu, and remembered thinking it was better but I'd like something even easier.  I'm literally to the point of taking a screenshot and transposing this darn thing to Photoshop....


texts: Low voltage grid frequency with renewable feed-in

texts:
If a low voltage grid's consumption equals to that grids renewable energy production, does it mean the transformator basically does nothing, like an open circuit? Are grid-tied inverters (smart) enough to keep the frequency and the phase correct to that extent?

How does one calculate a grids capacity to intake renewable energy, do you assume transformator works full capacity in the REVERSE direction? (pumping energy back to medium-voltage grid)


texts:
I'm new to digital electronics and I want to simulate in ltspice a circuit which contains a couple of 74LS04 inverters. What represents the "Test conditions" under the switching characteristics in the datasheet? All I have understood so far is that this inverter (being a non-ideal one) has propagation times. What are all the differences from the ideal inverter? What I have to modify in ltspice in order to simulate this inverter?

You can find the datasheet here: http://www.ti.com/lit/ds/symlink/sn74ls04.pdf

Thanks for help!


texts:
When designing analog circuits with feedback loops, attention must be paid to concepts such as gain and phase margin, open-loop gain, closed-loop gain, etc. in order to prevent oscillations (if you're not designing an oscillator, that is).

Why is the topic of stability and oscillation primarily relegated to the domain of analog electronics? Digital circuits certainly contain feedback loops. So why do we not have to worry about stability criteria and Bode plots when we design digital circuits?


texts: Does Bluetooth Low Energy need advertising channels for reconnecting?

texts:
In BLE, 3 of the 40 channels are used for advertising.  If two devices are
in the midst of a connection, the continuing communication hops about the
other 37 channels with no "wasted" power.
But, let me consider two paired-but-unconnected devices.  If I jam
just the 3 advertising channels (with overwhelming noise), is it possible
for them to connect?  If so, at least one device must be broadcasting
its ID periodically and I suppose Bluetooth standards could allow that
device to sit on any quiet channel it finds and have the other device
scan all 37 channels one-by-one.
Anyway (with or without jamming), what is the detailed procedure whereby
two paired-but-unconnected devices first find each other?
For some background, I have a low-power application where I want the radio
for one device to turn on once per day for the shortest possible time (to
send one message and receive one message).  I'd like to understand how much
time the radio will need to stay on for this if I use Bluetooth standards.
It helps me build up to understanding this with the two questions above.


texts:
I have a voltage divider, and the output goes to OP amp.

This is from my schoolwork.

-1 to +1 input
|
[R1] 1000 ohms
|
---> output to op amp
|
[R2] 1000 ohms
|
2v

How do I calculate output that goes to op amp?
Regular voltage divider formula is
Vout=Vin×(R2÷(R1+R2))
But lets say V1 is -1 and other end is 2v, what do i take for Vin? 3 volts?

Edit:
Found the whole exercise

V1 is 4v
V2 is from -1v to 1v
And where the ground symbol is, there should be 2v. What do I take for V2 in formula whem V2 is -1 or +1?


texts: Boost starup of a motor with a capacitor

texts: I have a RC car and I wonder if its startup speed will increase if I mount a capacitor in parallel with the battery. My thinking is that while the car is idling the capacitor will load. When I start the car, the capacitor will improve the internal resistance of the battery. Am I wrong? 1000uF is enough?


texts: Why does a car cabin fan need a big resistor?

texts:
The blower motor resistor for the cabin fan in a Volvo 850/V70 is so big that it is not even part of the motor. It has its own mounting. Here is a picture:

Why does the blower require such a large resistor? I have much larger fans in my house that have no such resistor.


texts: Difference Amplifier with 3 Op. Amp. How to analyze it?

texts:
I have to demonstrate, in the following circuit, that \$ V_o= \left( 1+\frac{2R_2}{R1}\right)(V_2-V_1) \$ if the Pot is in the halfway.

I know that the circuit inside the pink block its a Buffer for the differential inputs and that \$R_1\$ can adjust the Gain, but I don't know how Op. Amp. 3 is participating.

In order to facilitate the analysis, I split the Pot as shown in the image below pretending to do a current analysis, but I don't know how to interpretate the output voltage of the 3rd amplifier.

How should I interpret this circuit?


texts: IN-12A Nixie Tubes and K155ID1 (74141 clone) Power

texts:
I'm working on a design with some Nixie tubes (a clock, specifically to start, but I'm gonna have a ton left over for other things), and due to the rather expensive nature of the K155ID1/74141 ICs, I'm not real eager to just plug things in the way I think they should go and see if it blows anything up.

My understanding is that the ICs should take +5V and GND from my controller (Arduino, for instance) or directly from my power rail, as well as taking the BCD in the DCBA pins from my controller. To strike the Nixie tubes, I need 170+V at a relatively low amperage. From what I've read about the BCD decoder, my "outputs" (pins 1, 2, 8, 9, 10, 11, 13, 14, 15, 16) can be attached to the cathode pin on the Nixie tube corresponding to the number I want to light up.

I assume then that the ground pin on the BCD decoder needs to share a common ground with both the power source for the Nixie tubes and the power source for the IC itself. My question is, will that voltage (even with the low amperage) blow up my K155ID1's?


texts: Power amplifiers and maximum output amplitude

texts:
In the following circuit, what would be the maximum sinusoidal output voltage amplitude \$V_{omax}\$ which would yield a symmetrical sine wave without distortions when no load is connected?
I know the answer is \$3V\$, however, how is it derived? I thought normally \$V_{omax}=V_{cc}-V_{CEsat}\$


texts: Converting serial signal (12V-5V) and reading it using Arduino

texts:
I'm trying to read some commands from a device that uses non-standard voltage levels for serial communication. It uses 0V for 0 and 12V for 1. For all I know, TTL levels are 0-5V, so if I want to communicate with it using my Arduino, I need to level down the 12V to match the 5V. The Arduino Mega provides a pin with an output of 5V, so I figured I could use it, add a diode and get about 5V which I can connect to RX. For now I only need to read the data. TX pin stays untouched.

I made a schematic, presented below:

I figured that the drop on the diode (about 1.8V) will allow me to have (~)5V on the RX pin when the signal from the device is at 12V, and 0, when its 0V. 12V - 5V - 1.8V = 5.2V. The R1 is 3kOhm.
Could somebody explain to me why doesn't it work? Is this solution even proper? What do I need to change for it to work?

EDIT: I managed to get it to work - I modified the circuit:

The diode is a simple red diode, which has a drop of 1.8V. The three resistors are all 1kOhm. From my calculations, if the maximum signal voltage is 12V, I can now get 5V after reconnecting the diode to the GND.

What I don't understand is - when the pictured red line is disconnected, I get nothing - my Arduino doesn't respond. BUT when I connect the device's RX with TX I read the exact data I wanted! Now that's not very obvious to me, I got it accidentally by playing with the board. Is there an obvious reason why the device starts transmitting after I connect the red wire?

EDIT2: Below is the device's schematic. CONTROL SYSTEM is the only connector I am able to get to. 12V comes from a simple 12V adapter, ground is also connected to adapter. Rx is  connected to arduino, the rest is exactly like on the picture with the red wire. Bigger version on Imgur


texts:
I am designing a line following sensor and for this project i am confused between using an infrared diode reciever or an infra red transistor. I dont know the difference between them(as for a long time i thought they where the same). Please I need a full explanation about how they work and how they are used. And which one is better for a line follower. And if there is a specific model please tell me.
Any help is appreciated!
Thanks in advance.


texts: Can voltage drop across a diode be controlled by varying the doping level?

texts: For example, Can a silicon diode be designed to have a forward bias voltage drop of 0.4V or may be 0.9V?


texts: Debate on wiring risk of positive/negative wires along a path

texts:
I came across a design of a battery pack. As you see on the photo, the red wire is positive and black is negative.
The red wire lays across the top of the battery pack and comes to the connector.
One of my classmates said to me that, there is more risk of moving the red wire across the top of the battery pack, and I should move the connector to the left side and draw the Black wire across the top of the battery pack. So this way the risk of the short circuit will be less.
But does it really matter which wire goes across the top of the battery pack as both wires carry a total voltage?
If it is the red or black wire, both wires carry a total voltage of the battery pack. I think it does not matter which wires go across the battery pack. I want to get your opinions regarding this question.
Best Wishes

---------------Solution by Neil_UK in comments-------------
I redrew the battery from the comments and put the photo here.


texts: Can I use 2n2222 transistor instead of c9013 transistor in a vu meter?

texts:
I am building a science project for my friend. We chose to make a VU Meter.

I am planning to make the Vu Meter as the schematic in the image:

The audio source will be 3.5mm jack output of a smartphone.

I am getting all the components except the c9013 transistor at local shops.

So can I use the 2n2222 transistor instead?

If not then suggest the changes to make it work.


texts: Digital Potentiometer controlling DC motor speed problem: voltage won't step properly

texts:
I'm building a rheometer to measure the viscosity of liquids. I'm using a 4.5-10v DC motor which needs to be accurately controlled by a Raspberry Pi (the speed and torque must scale, so PWM is out).

I have been trying to control the motor with a 10k digital pot (MCP4131) in a voltage divider with a transistor to control the voltage through the motor.

In theory, the voltage should (as the pot sweeps through its range, 129 steps) vary between ~2.6v and ~10.5v.

In practice, the voltage only varies between ~7v to ~5v, reaching its minimum after only ~25 steps and then staying constant for the remaining 100 or so steps.

What is going wrong? Is there a better way of doing this?

This has been the bane of my life the last few weeks, any help would be greatly appreciated. If anything is unclear I will clarify as best I can.

EDIT: MCP3141 -> MCP4131


texts:
I need to create a water pump system for a modeled water tank.
Now I'm a complete noob so my ignorant self thought I could just buy a small DC pump, a switch and some connectors and off I'd go.
Doing this I depleted the battery in about 4mins of run time.
Connecting these items via a AC/DC converter power supply, resulted in the pump/motor stopping in approx. 2 mins and the wires getting really hot.
Am I going about this all wrong or is there something I'm missing? i.e. relay, motor speed controller, etc.
Can someone help me out with a wiring diagram for this or direct me to were I could learn how to do this? Much appreciated!

Specs of the components I bought:

Pump:
    - Rated voltage: DC3V or 4.5V
    - No load of water discharge capacity: 100L / H
    - Load rated current: 0.18A

Power Supply Adapter
    - Input: 100V-240V 50/60Hz
    - Output: DC 12V 5A max
    - Output adaptor jack size: 5.5mm x 2.1mm

Manual Inline DC Power Switch
   - DC Power Pigtail male/female:2.1x5.5mm
   - Voltage：5-12V
   - Max electric current:2A


texts:
Why do we need 20 ohm resistor at the input IN-?

datasheet: http://www.ti.com/lit/ds/symlink/ads8370.pdf


texts: What is a "loading capacitor for pin parameter measurement?"

texts:
I am designing my first PCB with an MCU and I see this section in the datasheet that brings up a loading capacitor used for pin parameter measurement.
I don't believe this is load capacitance for a resonator because that value you get from the resonator datasheet and the figure doesn't match the needed connections. From looking around it seems this is related to S parameters for high-speed PCB simulation and verification, but it's hard to tell for me. This is from STM32F446xC datasheet.


texts: PIC18F25K50 - 48MHz with internal oscillator does not work

texts:
I'd like to run a Microchip PIC18F25K50 at its maximum speed of 48MHz from its internal oscillator.

Here is the overview of the oscillator system from the datasheet:

The 16MHz from the HFINTOSC can be fed directly to the CPU by setting SCS = 0b10 (INTOSC). When doing so, I get exactly what I expect:

My code toggles an output, and the pulses have a width of ~250ns / 4MHz, which is the execution speed of the MCU of 16MHz/4.

Now, the 16MHz INTOSC is also fed into the primary clock module, so enabling the 3x PLL, setting the PLL postscaler to /1 , and choosing SCS=00 (Primary clock) should give a 48MHz clock / 12MHz execution speed.

However, that does not work. The MCU shows an extreme capacitive sensivity, it normally doesn't produce any pulses. When I put my hands nearby or even touch it, it starts to produce pulses of various, but extreme lengths. To me, it seems the MCU somehow catches noise and derives its clock from it. By the way, I also bypassed the PLL by CFGPLLEN=0, that doesn't change anything.

Does anyone know how to run the MCU at 48MHz from internal oscillator?

Here are my config bits:

// CONFIG1L
#pragma config PLLSEL = 1    // PLL multiplier: 0->4x 1->3x
#pragma config CFGPLLEN = 0  // PLL enabled?
#pragma config CPUDIV = 0    // CPU Clock divider: 0-> No divider
#pragma config LS48MHZ = 1   // USB clock: System@48MHz->0 System@24MHz->1

// CONFIG1H
#pragma config FOSC = 0b1001 // OscillatorConfig: InternalOscClockOut->1001
#pragma config PCLKEN = 0    // Primary clock: disable by software ->0 alwaysEnabled->1
#pragma config FCMEN = 0     // Fail-Safe Clock Monitor?
#pragma config IESO = 0      // Internal/External Oscillator Switchover?

and here my code:

void main(void)
{
    OSCCONbits.IRCF=0b111; // No divide -> 16MHz
    OSCCONbits.SCS=0b00;  // Primary clock
    //OSCCONbits.SCS=0b10;  // INTOSC
    ANSELA=0;            //Make PortA digital
    TRISAbits.TRISA0=0;  //Make PortA output

    while (1){
        LATAbits.LA0=1;
        LATAbits.LA0=0;
        LATAbits.LA0=1;
        LATAbits.LA0=0;
    }
}


texts: Electrical safety measures in LED bulbs for the European market

texts:
Which electric safety measures are required to introduce LED bulbs on the European market?

Which electric measures prevent that the plastic LED bulbs will melt down or ignite at the end of life?

I am especially interested in the measures to prevent dangerous failures.
There is a high chance that one part in of the circuit will overheat until it opens the circuit at the end of life. However I saw no thermal fuses in LED bulbs.
Please add references, where the requirements are defined.


texts: Powering refrigerator using solar inverter

texts:
I have got a 3 kVA (2400 watt) solar hybrid inverter (pure sine wave) which is connected to a 1280 watt PV array and 2 x 12 volt 150 Ah batteries. It is supposed to switch to utility mode if the combined voltage of PV and batteries goes below 23 volts.

This afternoon (during plenty of sunlight), I tried to power my refrigerator using the system but as soon as the compressor started, I could hear some knocking sound from the fridge, and at the same time, the LED lights in the house (also powered by the inverter) started to flicker.

Next, I tried using a voltage stabilizer on the fridge to see if that made any difference but the result was the same (knocking sound from compressor, and flickering lights).

The display on the inverter showed that it was producing enough output at that time for the required load (sometime like 550 watts). To validate this, I connected a 1200 watt halogen heater and ran a 100 watt ceiling fan, and it was able to power this load without any issues. The display on the inverter showed a load of 1.1 kW.

My batteries are about 2 years old and normally don't give a long backup. Even on a 150 watt load I might get about 10 to 15 minutes out of them. So, could the problem be that the refrigerator's compressor produces a sudden spike in the required load and the batteries are not able to handle this?

Or, do I need more solar panels to be able to handle this spike? I'm planning to run my DC inverter air conditioner on this during summer and want to know before I replace the batteries or buy more solar panels.


texts:
I have set up a 555 Timer circuit on my breadboard following this diagram.

These are the values I use:

R1: 1k

R2: 1k

C: 0.1uf

Vcc: 9V

The only problem is, on pin 5, I have a 0.001uf capacitor.  When I connect the circuit, the led I have on pin 3 (normally I have an 8 ohm speaker but I wanted to see if any current was being produced) doesn't light up.  Here is a picture of my breadboard. (Sorry for the horrible wiring... And the extremely large image)

The bigger capacitor is 0.1uf and the smaller is 0.001uf.  Also, wire colors don't mean a thing (again... sorry).

Thanks in advance for your help.


texts: Are Altium Vaults worth it for a small company?

texts:
I'm going through the process of starting a bunch of new design work in Altium at the moment at my company, and am trying to decide whether it's worth going through the effort of setting up the Altium Vault infrastructure, vs. just using traditional version control. Here are the pro's and con's as I see them:

Pros:

Very good design release and versioning process.
Easy way to create validated, trusted, versioned components.
Allows for concept of "items" and design reuse of validated blocks larger than the component level.
Makes it easy to share design data with vendors and verify that they're looking at the correct version of design data.

Cons:

Makes it very difficult for the individual designer to quickly make changes to schematic symbols and footprints for components, without going through vault release process.
Process to release components and "items" into the vaults is very complex and time-consuming.

In my brief research, it seems like it would take a full-time Altium librarian to keep the wheels greased on a vault and keep the release process of components and designs flowing smoothly. Do any of you out there have any thoughts and experience on the issue? Are there any other small companies or design teams (5-10 engineers working with Altium across design, manufacturing, procurement, etc.) who have found Vaults worth implementing?


texts:
I'm working on a remote (wirless) door opener and I need to install a device (just in the opener) at the entrance of a building where there is an electric opener. The problem is i can not install wiring, and i need to power my circuit. To do this, the only way that I thought without installing wiring or use batteries, is to use the wiring that reaches the lock to open the door. In this case what I do is hijack the original system cables and use them to carry the voltage to the device. I want to make it an universal device,  and usually, the electric opoeners works with 12 V dc, 24 V dc or 24 V ac, so my device must work with these voltages.

The problem is that my device should not override the previous system, ie, with the old system i must still can open the door. But because i'm using the drive cables i need another way to open the door with the old system.

What I need is:

A solution as simple and cheap as possible
Use only two wires to power and transmit data
Can send a single bit of data over the power line.
Make it safe.

The solution to which I have come is to send information (a single bit of information, on or off) that run through the power line. I've been reading about the PLC but is too complicated for my project, too expensive and much more than what I want.

This is the scheme of my solution:

I decide to make two devices, one located where the old system is, and another next to my device in the door opener. The first device generates the power (12v ac or 24v ac or dc) the power my device and the door opener, and also listen when the old system want to open the door. When the old system want to open the door it ativate a frecuency generator (for the prototype i'm using a 555) to modulate a ac signal over the power line.

In the receiver side i filter the signal and transale it to a on/off signal, when there is ac signal modulated over the power line is on, and when not is off. This signal goes to the microcontroller and then it opens the door or not.

For cupling the ac signal (with a frequency of 10 kHz) over the power signal i'm using a coil (10mH) in the power line and a capacitor (0.1uF) between the frequency generator and the power line.

In the receiver side i'm using the next circuit:

I am a newbie to electronics so forgive me if I made a huge failure. By the way, i proved it in a proto borad and it works, but i think that this is not the right way to do it.

I want to know if this is safe, usefull and how to improve it, or if there is a better and cheaper solution. If you need more details pls ask me.

Thanks for your help, and sorry for my english.


texts: How to use an optocoupler with a transistor on both sides?

texts:
I am trying to switch a 17VDC 30mA load with a Raspberry Pi. To provide electrical isolation, I am using a two channel optocoupler, a TLP621-2 (datasheet). The second channel is currently unconnected.
My understanding is that I can't drive the optocoupler directly from the 3.3 VDC GPIO pin on the Pi because the pin can only source/sink 16mA. So I'm using a 2N3904 transistor to control the LED in the optocoupler. Putting 17VDC 30mA on the coupler's outputs isn't wise either so I have a second transistor there as well.
The problem is that I don't know how to complete this circuit? I've tried different permutations on the output and can't get it to switch the load. I have no idea whether I have things hooked up incorrectly or I keep smoking ICs (or both?). The input transistor seems to switch as expected when I apply 3.3V to it's base, so I assume that the coupler's LED is activated. But nothing happens on the output. I'm wondering if I'm misunderstanding the TLP621's datasheet?


texts:
Update:

The VGA Simulator is up and running. You can go simulate your own designs or just use the example file to see it working. I also wrote a blog post to help anyone get started using it for their own VHDL designs.

I am making a VGA simulator or virtual monitor because Xilinx takes too long to synthesize VHDL (on my pc, and in general for large projects). With this VGA simulator, I can just run my testbench which logs to a file while running in a normal simulator such as Isim and then use that log file in my VGA simulator to generate the frames.

The VGA simulator decodes hsync, vsync, and rgb (5 major signals) to generate the frames.

Is there a way to get the resolution or pixel clock rate from just the 5 major signals? Right now I just have some text fields that you have to put it in manually (see form). I need the pixel clock rate in order to keep track of what pixel the system is working on.

I am assuming that every monitor uses 640x480 at 60 Hz as a default setting for VGA because I don't have to fiddle with anything to get it working. I understand that there is some EDID pins and some newer serial interface that are spec'ed out but are they actually used to determine a different resolution or fps/Hz? On the Basys 2, they are just grounded.

My simulator is working great right now but doesn't account for the back porch so I have blank space at the top left and some cut off at the bottom right. This is because I just look for a rising edge in hsync and vsync and start capturing. This is not a huge deal and easy to fix but I am unsure of the correct value to put for the back porch in order to work with a variety of peoples log files.

My VHDL design(based off of this design) has back porch of 48 clock cycles and for example this document says it should be 45, and this one says 48. What is the correct tolerance for the back porch or the proper way to synchronize to avoid these discrepancies?

Of course a monitor is designed to take this all into account but what are the proper ways to deal with tolerance in not only the pixel clock but how many cycles each process takes (front porch, back porch, resolution, fps)?

An example of a discrepancy: My design just divides the 50 Mhz clock on the Basys 2 by two to get a 25 Mhz pixel clock to drive the VGA when it is spec'ed at 25.175hz everywhere but of course you have to put your pixel clock in the form so it is non-issue at the moment for my design.

Here is just a nice diagram of timing of hsync and vsync (just a good reference):


texts: Can a CPU function with nothing more than a power supply and a ROM, using only the internal cache as RAM?

texts:
Can a CPU (such as the Intel i3/i5/i7/Xeon) with on-chip cache RAM use that as its only functional RAM, without any external memory banks attached?

Or must there be external RAM, and the cache cannot be accessed or used alone?

Modern desktop/server CPUs often have more internal cache RAM than many 1990's computers had in entire system memory, so there should be plenty enough there to run simple code.

CPUs from before cache existed such as the 6502 would be unable to do anything, as the internal CPU RAM only amounted to a few bytes for the address counter and accumulators.

This is not a question of running any sort of modern operating systems, but running simple code programmed into a custom ROM, or hand-entered with a hex input keypad.


texts: Prototyping a part with 2mm spacing on 0.1" matrix board?

texts:
I have an Airwave AWM682RX 5.8GHz video received and matching AWM683TX transmitter module. Oddly, one has pins spaced at 0.1", the other at 2mm.

So, what's the best way to make a part with 2mm spaced pins fit on 0.1" matrix board?


texts:
I've just been working my way through and getting more experienced with Altium, I've almost got it doing exactly what I need for my design. The last thing I can't figure out is how to define the guide pins that are part of the component in the PCB footprint. The board needs to house these properly because they protrude about 0.5mm below the switches feet.

Here the link to the switch datasheet.

Please can someone describe how create so sort of shallow drilled slots attached to the PCB footprint for these or something similar.


texts: Would I be able to charge my car battery with a DC power supply that outputs 12V 2.5A? I know real car battery chargers put out 12V 10A. Would it just take 5 times longer?


texts: What voltage should power requirements be listed as?

texts:
I am listing the power requirements for a culmination of multiple devices for the US and the EU.

For 120 volt mains, it appears most list the requirements (amperage) relative to 115 volt. Should I do this as well?

How about for 230 volt mains?


texts:
I understand that the return current will use the closest plane to the signal trace. So could you give me answers on these 2 specific conditions.

1)When we have lets say 4 layers where layer 1 2 3 are signal layers and continuous ground plane is at 4th layer. For all 3 layers' signals the return current path will be on 4th plane right since there is no other plane.

2) Now for second case, the 4 layer stack up is signal ground-plane signal signal. Assume that layer 3 have signal traces but i also poured copper for some vcc rails on some areas of layer 3 (not completely). Then if i draw a signal trace in 4th layer, will the return current be on ground plane at layer 2 or the partial copper pour on layer 3 for trace passing under partial copper pour and trace not passing under partial copper pour.

I hope i am clear.


texts: Question about the derivation of RC Filters frequency cutoff

texts:
We've learned that the operation in RC filters depends on how the capacitor reacts to different frequencies, in other words, the capacitative reactance.

The input is applied in series with a resistor in a "low pass filter" and the output is taken across the capacitor. Basically, this low pass filter passes low frequencies but blocks high frequencies.

I was wondering if anyone can assist me in deriving this expression

$$f = \frac{1}{2 \pi RC}$$

The book gives this curious expression which I hope makes sense to someone: $$v_{out} = v_{in}\frac{X_c}{\sqrt{R^2 + X_c^2}} $$ This is somehow connected to the expression above. I've tried reasoning with voltage dividers, but couldn't get such an expression:

$$v_{in} = I(R + X_{c})$$
$$v_{out} = IX_{c}$$

which gives the expression for the output voltage above. The problem with this "explanation" is that the same formula applies to the "high pass filter" where the input is in series with the capacitor and how could they both have the same output voltage?


texts: Making dual power supply from single for opamp?

texts: For the circuit of opamp 741. we have to supply the dual power for it. How can I make a dual power supply from single. For example, make a (+9V)-GND-(-9V) from single 9V battery ?


texts: What do we mean by EMI Signature? (Both theoretically and physically speaking)


texts: Connecting a sata cable to a usb hard drive circuit board

texts:
I am trying to connect a USB harddrive to a sata cable by attaching the sata cable to the drive circuit board and only using the usb to power the drive. This is for data recovery.

For reference I am trying to follow this page: How to connect and data recover from a WD HD

Since I do not have a spare harddrive to use a sata connector/interface from; I decided I would try connecting a sata cable directly to the circuit board.

I have sliced open a sata cable (images below) and there appears to be 4 insulated wires and 4 exposed wires. However, the sata interface only has 7 wires where 3 are grounded.

So my first question is, which are the ground wires? (im assuming the non-insulated wires).

My second question is do i pick any 3 of the 4 ground wires to connect?


texts: How to modify a 433.92 MHz signal to a 434 MHz signal?

texts:
I have these remote controlled wall outlets (Brennenstuhl Funkschalt-Set RCS 2044 N Comfort). And I'm trying to make an arduino circuit with an RF transmitter so I can switch them on and off without the remote.

I sniffed the signal from the remote with an RTL-SDR and found out that the signal frequency is 434 MHz.
So I went online and ordered an 434 MHz transmitter (from sparkfun).

After I hooked the transmitter to my arduino and wrote the code with the exact same signals as the remote had send out. I tested the circuit and saw that it didn't work.

So to see where it went wrong I also sniffed my signal from the RF transmitter, to see if it's the same as the one from the remote.
And I found out that the frequency of my 434 MHz transmitter is actually 433.92 MHz.

But this turned out that it wasn't a mistake. But the chip in the datasheet even says that it is 433.92 MHz.
And when I went online to find a real 434 MHz transmitter I couldn't find one, because all the 434 MHz transmitters that I found were also actually 433.92 MHz.

So then I tought how the hell has my remote a 434 MHz transmitter if I can't find one?
And I screwed it open and saw in the casing that even the transmitter of the remote is 433.92 MHz. But for some reason it sends out a 434 MHz signal.
So it must have some kind of circuit inside that modifies the 433.92 MHz to 434 MHz.

And now my question to you is:

How can I do that? How can I modify a 433.92 MHz signal to a 434 MHz signal?

Thanks in advance!

(I uploaded some pictures of the remote, the wall outlet, the RTL-SDR, the RTL-SDR captures on my laptop, The (simple) arduino circuit and the transmitter module)


texts: FTDI Chip Windows Error Message "USB device attached malfunctioned and windows does not recognize." Design Error?

texts:
My PCB has a FT230XS-R USB to UART communicating with an AVR chip. My first prototype board worked perfectly except for the USB problem stated in post title. I triple checked everything. Can NOT find why I'm getting this error. This may be a design flaw on my side? I followed the "Self-Powered" configuration on page 23 in the datasheet exactly as displayed.

Things I have checked:

Solder bridging?: Everything is reflow soldered, I still checked under microscope, it's perfect.

Still used a MM to check for shorts: None.

Checked cable: Good

Power supply quality: < 2mV peak to peak

Correct USB connector pins go to correct inputs: Yes

I triple checked the pinout on the datasheet against my PCB: Everything's correct.

I checked ground, VCC, and VCCIO values. Everything's normal.

I remade a PCB, I left every component unpopulated except for the FTDI chip and
peripheral components needed to run the chip. Still had the same problem.

I tried removing RX and TX LEDs: Nothing.

I then removed 47pF caps and 27 ohm resistors: Nothing.

I am at a loss. I contacted FTDI. They only said I have a short somewhere, and they asked for a schematic. I sent them the schematic, never heard back from them.

Could vias on my USB signal lines be corrupting the signal? Any info is greatly appreciated. I uploaded only relevant schematics and PCB design snapshot.

Please ignore U9 and pads directly above it, they are unpopulated. They were never populated for either test.

Thank you so much.


texts: Can transceiver replace SPI, I2C and other "normal" methods for high speed data transfer between FPGAs? If so, how?

texts:
SPI, I2C and UART are some well known serial methods for data transfer between devices on the same PCB. However, they all have a data rate bottleneck which is significantly lower than Multi Gigabit Transceivers (MGBT) like the ones used with PCIe and USB among others.
Is it possible to replace these and just use a MGBT for data transfer between FPGAs found on the same PCB? If so, how? Is it also possible to use the MGBT to transfer data from one PCB to another, what guidelines must be followed in this case?
Cyclone V, Cyclone 10 series Intel FPGAs


texts: Optimizing geometric dimensions of the stripline in AWR DE (Microwave Office) or similar software

texts:
I'm designing a stripline step inductance to compensate the capacitive impedance. My goal is to minify the WSVR parameter of the port and I may vary the dimensions of the stripline (widths and length) but the sum of lengths must be constrained by one exact given value (I'm working on improvement of the part of existing plate and the remaining part is not to be changed). Here's the simplified example drawing.

Is it possible in AWR Design Environment (former Microwave Office)? I know you can optimize absolute parameters but how about relative parameters? Currently I  manually tune these lengths and widths but I want to automate it.


texts:
At the university I learn only the Microchip microcontroller, but I would like to improve my knowledge. I ordered a development board based on Samsung S5PV210.
The manufacturer also provided a Linux distribution with this development board, but I would like to start from the basic, for example to blink a led, in this case I don't want to install a Linux, I just want to simply blink a led.

Where can I start?

How can I compile such a simple code?

How can I upload the code to the microcontroller?

I'm using Ubuntu 12.04.


texts:
I have a circuit which turns a 230V 50hz AC motor on and off by use of a relay.

I've tried to arrange it so that the relay would be turned off when the current through the motor is zero. Of course, it turns out this doesn't work, since the release time of my relay is 3-5 ms, and if I arrange to open the contacts at 0A current, the current will be at its maximum at the end of the release time (5ms). This is because at 50hz there are zero crossings every 10 ms, and the peaks are 5ms after the zero crossings.

I then experimented with turning the relay off at different phases. It turns out that the best results seem to be obtained when releasing the relay at maximum current. Then I consistently get clean waveforms with no voltage spikes.

If I try to release the relay at 3ms before the zero, it sometimes turns off cleanly, but sometimes there are some pretty big voltage spikes (>500V) just after the zero-crossing, and then the relay keeps conducting all the way through to the next zero crossing.

Turning the relay off at maximum current seems to give consistent good results.

What is the physical process that keeps the relay conducting until 0 current? If I switch a very light load the relay turns off "when asked to", and doesn't keep on conducting until the next zero-crossing.

Is turning the relay off at maximum current in the AC cycle advisable?


texts: independent 1 sec delays for 4x NiMH charger

texts:
I want to make a 4x single  cell NiMH charger.  using the pic 18F4550 DIP family using the MPLAB and C18

Q1.  I need  4 independent 1 second timers.

Here I ran into my lack of knowledge on  the way the 18F guts are  shared for parallel tasks.
 I of course could use 4 x series 1Meg resistor with 10 uF  on any port pin.

When a cell is inserted for charging a port pin will go high applying 5 V as a driving voltage.

Using an analogue input pin , maybe AN0, the 63% point can be detected and flip that  driving  port pin back to zero.
 As there are four cells, they will require  four analogue input pins, sounds a bit wasteful of analogue pins .

I also thought about using four digital input pins  to change from low to high as this is a cmos chip  and they flip at 2/2 Vdd.

The toggle will take place when   1 second has elapsed at the 63% charge voltage.

But I really want to use  the onboard digital timers, taking me back to my initial   question Q1

Help please

Fred


texts: Simple frequency-tunable spark generator?

texts:
This may sound weird, but...

I am attempting to design a steampunk / gothic horror-styled electric harpsichord, with sparkgaps as the sound source in the vein of musical Tesla coils.

Unlike musical Tesla coils, any particular spark generator need not be dynamically tunable for different frequencies--there will be 88 of them, one per keyboard key, manually tuned to a single note at a time. I would prefer if the frequency could be tuned by screwing a threaded steel rod into or out of a solenoid to alter inductance, but a potentiometer or variable capacitor any other sort of mechanically-adjustable tuning component is acceptable. Also unlike musical Tesla coils, the sparks need not terminate in open air--and I imagine it's probably best if they don't, since there will be 88 of these things packed fairly close together.

To fit the aesthetic, it would be ideal if such a circuit could be constructed entirely out of resistors, capacitors, and inductors--i.e., discrete components that I can make by hand by winding wire into coils, rolling up laminated sheets of metal foil and paper, etc., but if a transistor or or diode or something is required per spark generator, so be it.

The intended behavior is that, on activating a switch (keyboard key), a spark should be generated which produces a specific audible tone, and either continues indefinitely while the switch is activated, or decays after a fixed but significant amount of time (analogous to a plucked string ringing down).

What is the simplest / most robust circuit I could build to do that?


texts: If  a   microphone  has an  output  voltage of  1.45mV  @   1   Pa  and a   microphone  preamplifier    adds    50dB    of  gain,   what    would   the voltage at  the output  of  the mic pre be, assuming    the pressure    applied to  the diaphragm   never   changes?


texts: STM32 - reading serial number on command line (with st-flash)

texts:
I'm looking to programmatically read the serial number out of a device which uses an STM32 (L07x / L08x / L010). I can read the serial using the STM32 St-Link Utility GUI by reading addresses 0x1FF80050, 0x1FF80054, 0x1FF80064 (using size: 0x4, data width: 32 bits).
I now need to do this programmatically. I'm using st-tools to flash firmware, so thought I could use this to read the addresses out.
I've tried to do it as follows:
st-flash --format ihex read part1.hex 0x1FF80050 32
st-flash --format ihex read part1.hex 0x1FF80054 32
st-flash --format ihex read part1.hex 0x1FF80064 32

It produces an output which I'm finding difficult to parse to extract the serial I need. E.g. part1.hex produces this:
:020000041FF8E3
:100050003139510E363135341100000000FFFFFFF9
:1000600011008C6715002E00000000111100001116
:00000001FF

...where the St-Link utility gives me 0E513931.
I'm not hugely familiar with STM32 kit - can anyone advise if there's a more concise way to retrieve the serial number?