texts: What does a AA battery marked with R6P mean?

texts:
So I found on Quora.com in the name LR6 battery that the L stands for alkaline, the R stands for round, and the 6 means it's a AA size battery. However I have another AA battery with the name R6P. In this question on this site it's said that R6P can both be zinc-carbon or manganese-zinc. Is there a meaning of the R and the P in this? Is there a place that shows what these letters mean? On this R6P battery it says "not to be substituted for alkaline (LR) batteries. Does this mean it has limited uses? For example can I use it for a wireless mouse or keyboard?

Edit: Also, both LR6 and the R6P are marked 1.5 volts. I've just opened up the R6P battery and it looks like this:

Also, I've read a bit about zinc-carbon batteries, the article at Wikipedia says that the chemical reactions is from zinc and manganese dioxide. So in the question I linked does zinc-carbon and manganese-zinc mean the same thing?

I've just looked up manganese oxide and it look exactly like what I saw as the filling around the rod. It looked like this:
Manganese dioxide

So I guess the centre rod is carbon and the filling around it is manganese dioxide?


texts: Fiber optics module: built in or plug-in module?

texts:
I am designing an Internet of Things system with fiber optics as its transmission medium (for its immunity to various kinds of interference and inability to carry a shock from a failed high voltage interface to the controller unit, school project, don't ask)

I am here asking whether I should socket the fiber optics module (possibly using a card edge connector), or I should just build the transceiver in? I do have space constraints.

If I socket the transceiver, which should be designed to be universal to all components that can accept one, are those signals and voltages adequate:

+5V
GND
VDD (the system's IO voltage, some parts of the design use 5V logic, while some use 3.3V)
TxD
RxD

And what is the appropriate kind of card edge connector?


texts: Improve Quartus partial compile or recompile time

texts: I run Altera Quartus, and I'm using the SignalTap logic analyzer on a Max 10 FPGA. It takes tens of minutes to compile, and every time I'd like to add a signal to SignalTap, I have to compile again. The rapid-recompile button is always grayed out, I don't even know what it does, I've never had the option. A lot of times, I'm not changing my design just SignalTap, but Quartus wants to recompile everything which seems like a waste of time. Is there a way speed up the compile time (or changes to only apply to SignalTap)? Using Quartus 15.1


texts: What is the motor starting current and motor stall current for BLDC

texts: What is the motor starting current and motor stall current, can anyone help with equation of how to find starting and stall current of bldc motor with above information


texts: Convert 2s pulse into short pulse to wake up ESP8266

texts:
I have an ESP8266 that does something, then goes to sleep.

I also have an AM312 PIR sensor which wakes up the ESP when activated.
The PIR generates a 2 second long pulse when activated.

The ESP wakes up when RST pin goes low. I use the PIR output to drive a transistor to pull down the RST pin.

This works fine, the problem is, the ESP only wakes up once the 2 second pulse is over, and this slow wake-up delays the ESP's response.
IOW: the ESP needs a short negative pulse to wake up, but only wakes up when the RST pin goes high again. While it is low, it will not wake.

How can I convert the 2s pulse from the PIR into a short pulse, to trigger the transistor, and wake up the ESP faster?

This is a low power battery-driven application (hence the sleep), so I hope there is a simple low-tech solution to this problem which won't blow my power budget.

The LED shown lights up as status to show when the ESP is awake.

Transistor is a 2N2222a.

The 47k resistor between power rail and RST keeps the RST pin high during normal operation.


texts: Unexpected Behavior: i2s L/R clock only works under arbitrary conditions?

texts:
I'm new to Verilog (and HDL at all) and working with a Cyclone II EP2C5 Mini Dev Board in Quartus II (version 13sp1 to be compatible with my cheap FPGA).
I use the below two modules (one mostly just a container) to try and generate an extremely basic i2s waveform. The output is a 1411200Hz bit clock signal (with expected jitter) and a rock solid 44.1kHz LRClk / Word select signal. See the below image and compare with the hard-coded sample values I'm using.

module i2sTest(
    input           CLK50MHZ,       //crystal input
    output          BitClk,         //1.411200 MHz, or very close at least
    output          LrClk,          //44.1 kHz aligned with BitClk falling edge
    output          i2sData
);

i2sOutput i2s(
    .CLK50MHZ (CLK50MHZ),
    .sampleL    (16'b1000000000000000),
    .sampleR    (16'b1000000000000000),
    .LrClk      (LrClk),
    .i2sData    (i2sData),
    .BitClk     (BitClk)
);

endmodule

module i2sOutput (
    input                           CLK50MHZ,
    input   [15:0]      sampleL,
    input       [15:0]      sampleR,
    output  wire            BitClk,
    output  wire            LrClk,
    output  reg             i2sData
);

//generate the bit clock
reg [7:0] BitClkAccumulator;    //counts up to alternating 35/36 master clock cycles
reg  BitClkAccToggle;                   //tracks the alternation
always @(posedge CLK50MHZ) begin
    if ((BitClkAccumulator + 1) == (35+BitClkAccToggle)) begin
        BitClkAccumulator <= 0;
        BitClkAccToggle <= ~BitClkAccToggle;
    end
    else
        BitClkAccumulator <= BitClkAccumulator + 1;
end
assign BitClk = (BitClkAccumulator < 18);   //50% duty cycle

//generate the lr clock
reg [7:0] audioClkGenAcc;       //counts up to 64
always @(negedge BitClk) begin
    if (audioClkGenAcc + 1 == 32)
        audioClkGenAcc <= 0;
    else
        audioClkGenAcc <= audioClkGenAcc + 1;
    case (audioClkGenAcc + 1)
        32: i2sData <= sampleL[ 0];  //I know this isn't accounting for every bit of the inputs, please ignore this for now
         1: i2sData <= sampleR[15];
         2: i2sData <= sampleR[14];
        16: i2sData <= sampleR[ 0];
        17: i2sData <= sampleL[15];
        18: i2sData <= sampleL[14];
    endcase
end
assign LrClk = (audioClkGenAcc < 16);

endmodule

However, making one of any number of slight adjustments to this code, the LrClk frequency becomes extremely unstable. My favorite example of this is as follows: if I change the i2sTest module to connect this literal to the i2sOutput module:
.sampleR    (16'b0000000000000000),
Then I get this output:

Have I discovered a bug in this older version of Quartus? Am I violating a Verilog rule? What's going on here?


texts: Is it possible for the transfer function of an RLC system to have zeros other than at the origin?

texts: I could not find a counterexample to the claim that the transfer function of an RLC system can only have zeros at the origin. Is this a true statement?


texts: Controlling two DC brushed motors, 12V and 2.4V, limiting current while also supplying logic circuit

texts:
I have a system which is going to employ two DC brushed motors. The main power supply supplies 12V and is rated for 3A. I'm attempting to maximize the available current to each motor. The smaller of the two motors requires ~2.4 V nominal and runs well for the job with a limit of ~300mA. The larger of two motors requires 12V and I would like to give it as much current as possible, like ~2.5A. The main supply will also need to power a logic bus anywhere from 1.8 to 5V, but I don't think that will require very much current at all, still, I'd like to leave it at least 50mA. Both motors will have speed control, which I plan to use PWM from the MCU to achieve.

The size constraints for the design are quite small, and it must be very efficient to make use of all the available current and not get hot at all. I'm not very familiar with driving motors or regulating voltage/current since my background is mostly with logic circuits. I'm hoping to get some suggestions on how to design such a circuit and maximize the efficiency. What type of regulators should I be using? How can I ensure that the current never exceeds a maximum value to the motor circuits? How do I protect my logic line?

I really appreciate any help you can provide.


texts: Amplify and convert negative pulse to positive pulse

texts:
I am looking for design recommendation. Attachment is the block diagram of the system. We have a single photon detector (SPD) (https://www.idquantique.com/quantum-sensing/products/id281/) outputting -0.1V, > 5ns pulse of burst rate up to 10 MHz. We need to count these pulses using a photon counter. Our photon counter takes CMOS input pulses only. I need to convert this negative -0.1V to CMOS signal.
I need to make sure the amplifier will not affect significantly the timing jitter of the output from the SPD which is 20ps. I want to maintain this number as close to 20ps as possible.

I chose this op amp https://www.analog.com/en/products/ad8009.html#product-overview
This is 5.5V/ns slew rate, 545 ps rising time, and 10ns settling time.
Please advice me on this selection.


texts:
I'm trying to build "arducam-bluetooth-module-wireless-image-system" using an NRF24L01.
I wish to have a long range transfer of a single image from a remote location to my Android phone whenever it becomes within range (once per day).
I figure this should be possible because I can use a beacon like Stick n' Find to transmit temperature, so, why not an image.
Just not sure if the NRF24 is the right piece of hardware to achieve this.
(I'm stuck trying to get my Android to find the Arduino over bluetooth.)

Related - Is anyone interested it helping to prototype some projects to satisfy niche use-cases?


texts: Difference between 110V and 220V power outlet?

texts:
What exactly is the difference between a 110v and a 220v labeled power outlet?

As far as I can see, the outlet is just a piece of plastic with some metal connecting to the power cables. Both types of outlets seem to be identically built.

Does it pose a problem to mount a 110v power outlet on a 220v power cable?

To clarify, the plugged in devices are using 220v as the power system provides, the question is really just about the power outlet itself.


texts:
Determinate the power of the discrete signal:

$$x[n] = u[n] + (-1)^n + (\frac{-1}3) ^n * u[n]$$

where:  $$u[n] =
\begin{cases}
\ 1,  & n \ge 0 \\[2ex]
0, & n \lt 0
\end{cases}$$

The answer I got is 1 (Correction: the answer i got is 1.5), but i'm not sure if it's the right answer.

What I did:

knowing that $$Px = \lim_{N\to \infty} \frac{1}{2N+1}*\sum_{n=-N}^N x[n]^2$$

then you put all inside the limit:

$$Px = \lim_{N\to \infty} \frac{1}{2N+1}* [(\sum_{n=0}^N 1)+(\sum_{n=-N}^N((-1)^2)^n) + (\sum_{n=0}^N ((\frac{-1}3)^2) ^n)] $$

now we have: $$(\sum_{n=0}^\infty ((\frac{-1}3)^2) ^n) = \frac{1}{1-\frac{1}{9}}  = 0.9$$

$$(\sum_{n=0}^N 1) = N+1$$

$$(\sum_{n=-N}^N((-1)^2)^n) = 2N+1$$

so: $$Px = \lim_{N\to \infty} \frac{1}{2N+1}* [(N+1)+(2N+1) + (0.9)] $$

$$Px = \lim_{N\to \infty} [(\frac{N+1}{2N+1} )+(\frac{2N+1}{2N+1}) + (\frac{0.9}{2N+1})] $$

Applying the limit:
$$Px = [(\frac{1}{2} )+(1) +0] $$

Result: Px = 1.5


texts:
Considering that FPGA can be programmed with various drive current, can we rely solely on this for limiting current through an LED diode attached to the pin of the FPGA, without using series resistors? Or to broaden the question, what is the mechanism for controlling drive current within FPGA?
I am talking about signal LED diodes, commonly used for indication.


texts: I'm working with a board design that uses a Xilinx CoolRunner II CPLD (XC2C256-7VQ100I). We're currently working with the customer, and setting up the pins they'll be using external from our board to control our device. JTAG has several lines we'll use to program the CPLD on each part (TDO, TCK, TMS, TDI). In our production environment, we'd like to use several external pins to hook up to these lines to program the device. However, the end customer would like to ground these pins (Since our product will be fitting into an existing design). My question is, will there be any repercussions I need to consider about grounding those 4 pins on the device? (On the CPLD the JTAG lines are pins 45, 47, 48, 83). I'm fairly sure it shouldn't cause any issues, but haven't yet been able to find a definitive answer.


texts: How to increase pcb trace width after fabrication

texts:
I am new to pcb design and my first designed pcb is burning, I have checked some traces and I found this:

C18 capacitance is 0.1uF and 100V rated. The problem is that slim trace width is only 0.2mm. So maybe this might cause some burning. is there any way to fix this issue?


texts: ESP32 grilled with simple MOSFET switch for 12V water pump

texts:
I've soldered a small PCB around an ESP32 with following components:

ESP32 Dev v4
Water pump with 12-24V and 4.5-6W rating
Power supply with 12V and 1A rating
Capacitive sensor with analog output
IRFZ44N : N-MOSFET

The circuit does the following:
Measure soil moisture and turn on the water pump accordingly. When the soil is too dry, the ESP32 pulls the gate of the MOSFET high, which shorts the drain over source, source is connected to GND. The gate is normally pulled to GND with a 1k pull-down resistor.
The circuit was working fine with 5V power supply over PSU USB or laptop USB.
However, when I plugged in the 12V rated PSU, the ESP32 literally burnt to death.
Please check my hand-drawn schematic here:

Soldering was fine (since it worked for 5V as well):

I've previously powered an ESP32 using a 12V PSU since the on-board AMS1117 linear regulator tolerates this voltage.
I've also checked the polarity of the PSU before plugging it in. The linear regulator still seems to work since it outputs 3.3V, however the ESP32 vaporated.
I can not see any major flaws in my design. I just think it is a bad practice to switch GND instead of 12V with the MOSFET but I just did that out of convenience because I had N-MOSFETs lying around here.


texts: Finding the settling time of an oscillatory response

texts:
I was reading my book on circuit analysis on chapter about RLC response and became curious about how to get an approximate value for the settling time of the response. Particularly this response

My first approach was to use the upper envelope of the response and equate to 1 percent of its maximum value and find the approximate settling time which turns out to be Ts = 2.30s.

Now my question is if there's other method that I can use to better approximate the settling time. My book speaks about a trial-and-error solution but did not show how it's done. Please tell me how to go about it. TIA!


texts: Are there any safety concerns to have an current flow through a bronze wire that is connected to a copper wire?


texts: Wonder if someone could explain which diode lights first

texts: Wonder if someone could give a very detailed description of the process on how this circuit works and which initial diode lights up and why!


texts:
I need a stable, low noise voltage reference that I can adjust between 1.4V and 1.8V. The output should source or sink up to 0.25mA @150Hz max. The output will provide a +1.65V bias for a bipolar signal driven by another op amp into the ADC on a microcontroller. (I need some adjustability because the bipolar signal has got some d.c. offset error I want to null out).

A similar question was posted here Are all voltage reference ICs able to sink as well as source current?
and I wanted to develop that with a proposed design (below).

My question is: where would I put a capacitor to decouple noise in the reference? Could I assume a 100nF between the 2.5V reference diode's anode and cathode would suffice or would I ned further filtering on the input?

(By the way, I'm changing from the TLE2141 to a TL071AN in my circuit because the TLE2141 has too large a supply current.)


texts: 3.3 to 5V logic translator followed by a long cable

texts:
I was testing the TI TXB0108 today to shift 3.3V from a MCU to a DSP. The DSP connector only has 17 digital inputs, and a ground (no VCC), and expects 0-5V. The 3.3 and 5V power are both being supplied on the MCU side. I first tested the output with a scope, and got nice clean transitions. However, once I added a cable (twisted pair ribbon, but only 18" long), the first 50-100 us of the rise was a mess, and then it quickly reached 5V, with a relatively quick fall.

I'm curious what I could do differently. This application does not require a timing signal, only 16 bits and a strobe bit (to latch the input). The strobe will only fire at most 10 times per second (pulse of any length > 250 us) but there needs to be sub-millisecond delay. And as far as I can tell, the DSP input is buffered, so there should be much of any current draw (but I haven't verified this yet). Also, although the logic level translator is bidirectional, the signal will only -ever- go from the MCU to the DSP.

Update

Of course (sadly), I can't reproduce the problem today. I get -exactly- the same scope trace with the following:

scope tied directly to level translator
scope connected through 18" of twisted ribbon to level translator
scope connected through 18" of twisted ribbon to 100 Ohm resistors to level translator
scope connected through 18" of twisted ribbon to buffer to level translator

I didn't have enough resistors to try more than 1 bit and the strobe, so I wasn't able to test more. However, I did occasionally get flaky results with the ribbon tied directly to the level translator, so I added the buffer (which has 6 channels), so I could get at least 5 bits - and it was rock solid.

Image:
Y1 is strobe, Y2 is bit0. The strobe is delayed by 50us.


texts: What does a capacitor “Series” signifies?

texts:
I am an electronics beginner trying to shop online for capacitors but so far I am failing miserably.

My biggest question right now has to do with capacitor series. Below is a list of a couple of capacitor series categories in case I am not being clear on what I am talking about:

125L Series
2C20 Series
2C25 Series
A Series
Aximax Series
C052C Series
C315 Series
C322 Series
TCD Series
WKO Series

Below is the link to the page that contains the capacitor series. The capacitor series are listed under a filtering table column named "Product Range".

http://www.newark.com/webapp/wcs/stores/servlet/Search?st=ceramic+capacitor&catalogId=15003&categoryId=800000009504&langId=-1&storeId=10194

I would like to know if someone could tell me what role does the capacitor series plays when choosing a capacitor. So far, it looks to me like capacitor series is just a form factor but I have a feeling is more than that.

Also, if it’s ok, could someone tell me what series capacitor should I be looking at if the use that I have for the capacitors is just for beginner projects?

Thanks.


texts:
i've been looking for a replacement 5k potentiometer for a mobility scooter.

they have 312 deg mechanical rotation but only 45deg electrical spread, so the center 45 degrees are 4ohm-5kohm.

they are quite pricey.

would it be difficult to take a more standard (cheaper) pot and modify it, either with components to alter the resistance or maybe a 0 to 30k pot and mechanically adjust the mounting?

all input appreciated, thanks.


texts: Trying to understand why the signal was inverted on this RC step response equation

texts:
I am watching this video where the guy is deriving the equations for the step function of a series RC circuit.

At some point he has the following equation:

\$ \frac{dt}{RC} = \frac{dv}{v_s - v}    \$

and he suddenly multiplies both sides by -1 in order to get a minus sign on the left side and invert \$v \$ and \$v_s  \$

\$ -\frac{dt}{RC} = \frac{dv}{v - v_s}    \$

He justifies that by saying "lets do that because we want to write v minus v_s"

what?

Obviously he knows that that minus sign will be the exponential exponent, making the final result correct but this is not a mathematical justification.

Do you guys have any idea why?

NOTE: you can see the sign change on the right side, on the line the integral symbol appears for the first time.


texts: Ringing problem Bootstrap for high side mosfet driver

texts:
I am using three phase half bridge inverter to power a PMSM motor and bootstrap for the high side MOSFET.
The schematic is in attachment. Gate driver is Si8273, MOSFET is IPT015N10N5. But when I measured the high side  signals, I got pretty high ringing during turn-on. The measured points in attachment was between phase output and HV_GND(I know I should measure between gate and source). The measurement between high-side gate and source (phase output) is shown in attachment VGS.
What I am expecting from the VGS is a square curve to 60V, but as we can see is a 12V signal with ringing.
Maybe can someone give me some advice where the problem is, and how it occurs.
Thanks so much in advance.

The layout is pretty complecated, I cut one half-bridge for you guys to discuss. The red arrow is on the VCC-layer for the HV_48V as DC-Link supply; the yellow arrow is on the GND layer; the green arrow is on both top and bottom layer for the phase. Between the green arrows is a Hall-effect current sensor.


texts: What software do people use to make digital circuit schematics?

texts: What software do people use to make electronic circuit schematics like this or similar.I tried using multisim but it seems to miss most chips.


texts:
I have answered questions here before, but this is my first own question.

I purchased three ZeeVee HDb620 QAM HD modulators that were supposed to be working when removed from service, but only one of the three works.  These units are centered around an FPGA, and they attempt to boot with a correct initial sequence, but fail to fully boot. I would like to repair them because I bought them very cheap, but I am unwilling to disassemble them at this point unless there is a decent possibility that I could repair them.  Due to the fact that I can return them for a partial refund, it would be worth it for me to keep them and try to repair them if there is even a 20% chance that it is possible.

I am very well versed in logic, but not very familiar with FPGAs to the extent that I don't know if there is a way to transfer the FPGA code from the working device to the FPGAs on the failed devices.  I don't know the model of the FPGA without opening them up, so I don't know if the FPGAs are non-volatile or if they are dynamically programmed from a flash chip, etc.

I have only provided specifics of my situation to possibly narrow down any possible solutions for me, but otherwise my question stands alone for any generic device:

Can a failed device that has an error loading the FPGA configuration be repaired utilizing an identical working device that works properly?

Edit: I have JTAG, Bus Pirate, USB-Serial TTL interface, HP Logic Analyzer, etc...

Edit 2: The Verilog or VHDL code encodes MPEG2, so it will be covered by licenses for MPEG2 codec, which may be an obstacle if I would need to try to get a copy...

Thanks!


texts: Shaded pole motor coil calculation, rewind 110v motor to 220v

texts:
I have yj61 series motor. Something like this

It's rated AC120V 60Hz 3000RPM and was damaged by accidental connection to 220v mains. I can't find suitable spare motor, so I have to rewind this one anyway.

And if I have to rewind it, then I'm curious if it is possible to change its winding to make it 3000rpm at 220V 50Hz, to remove 220v-110v transformer from the setup.

Could you provide me with book reference or any other material which  explains how to calculate coil parameters for shaded pole motors?
Ready to use answers (like "use doubled number of turns with a half-diameter wire") are welcome too.


texts:
I have 2 devices connected to my ATMega328 USART pins. One is PL2303 USB to TTL converter and the other is Bluetooth <-> USART adaptor.

I was advised that I should not have 2 devices connected at the same time to the USART pins on my AVR as data corruption may occur if both devices are active at the same time and try to drive the AVR RX pin.

The solution I was suggested was to have diodes on the TX line of each of the devices along with a pull up resistor on the AVR RX line. Something like this ..

Can someone explain how this would work?


texts: Setting register values over i2c from Linux (managing power on a PocketCHIP)

texts:
TL;DR - I need to set the contents of a register on a power management IC over I2C from Linux running on an SBC. I've found the datasheet for the IC, but I don't know how to use the information in it to formulate the correct i2cset command. Skip to the end of this post for the core questions.

I am running a Linux SBC (Next Thing CHIP) which uses the AXP209 IC for power management, balancing between USB, GPIO and battery power as needed. It's part of a handheld (PocketCHIP) which has a LiPo battery attached.
I've been happily running this daily for a while as an ambient screen, powered from a standalone USB power supply. However, more recently, battery charging has been very noisy and Linux on the unit keeps shutting down with low power warnings, despite being plugged into USB power. This is new behaviour, and the USB power supply hasn't changed.
My working theory is that the battery or the AXP209 is failing, probably the battery.
Ideally, I'd be running the unit with no battery attached at all, entirely from USB power. However, if I disconnect the battery the unit doesn't boot. Failing that, I'd like to be able to disable the charger, or tell the CHIP / AXP209 to draw as much power as it needs.
Eventually, I found my way to wiki pages about Power on the CHIP and the AXP209, and the datasheet for the AXP209. I can see two promising commands in the datasheet which can be set by manipulating registers over i2c:
Page 18:
If  the  system  just  utilizes  the  USB  for  power  supply  rather  than  communication,  or  the  USB  poweradapter is utilized, AXP209 can be set to “VBUS Direct Mode” by modifying register REG30H[6]
(if the CHIP really is suddenly unable to draw enough power from USB)
Page 19:
The  default  state  of  the  charger  is  “Enabled”.  (It  can  be  programmed  via  registers.  Refer  to  register REG33H.)
(seems to be the closest thing to 'don't use the battery at all')
I can see these i2cset commands listed in the CHIP wiki:
# Set to 900mA
i2cset -y -f 0 0x34 0x30 0x60

# Set to 500mA
i2cset -y -f 0 0x34 0x30 0x61

# Set to 100mA
i2cset -y -f 0 0x34 0x30 0x62

# Set to no limit
i2cset -y -f 0 0x34 0x30 0x63

# Show current value
i2cget -y -f 0 0x34 0x30

and I understand that these are setting values in REG30H (0x30) on the AXP209. However, I don't understand enough about registers and bitbashing to interpret the bit values in tables 10.11 and 10.14 on pages 33 & 34 of the AXP209 datasheet into i2cset commands I can use on the CHIP. I'm a pretty decent programmer, but in fairly high-level languages like Python. Low-level stuff like this is alien to me.
So, my core question: what values do I need to set in REG30H[6] or REG33H on the AXP209, and what are the correct i2cset commands I can run on the CHIP to do that?

EDIT: i2cget -y -f 0 0x34 0x30 returns 0x60 just after booting, which indicates that the device is set to draw 900mA by default.


texts: Can someone explain to be what I am supposed to do in these questions (simplifying boolean algebra)?

texts:
I'm reading Digital Design by M. Morris Mano and I am solving the exercises. I got stumped in some of the questions.

In this one I am not sure how to do b). To get F I did the SOP using the truth table. Then I took the complement of the SOP(which if I am not wrong is done by negating it and then applying Morgan's Law). However the SOP is just y. The complement is then not y? So the minterms of the complement are the maxterms of the original function?

How do I solve this? I'm thinking about using Karnaugh maps to get the expressions and then taking the complements and using a truth table? Is that what I am supposed to do?

This one doesn't make sense to me. What if all the minterms are zero? I'm not sure what I am supposed to do.

Is it possible to do this one without Karnaugh maps?

What's the inhibition operation?


texts: LM317 based voltage regulated high current power supply problem

texts:
I am new to electronics and have been exploring easy to make DIY things for a while now.

I am using the following circuit to make a voltage regulated high current DC power supply.

The problem is, I can't adjust the potentiometers to get an output voltage beyond 11-12 volt. The DC output is always between 11 - 12 volts, neither less, nor more. By the way, the transformer is 12-0-12 5 amp, and I am measuring no-load voltage with a digital voltmeter.

My questions are:

Is the circuit correct, regulated voltage at the base of 2N3055 will regulate the voltage at its emitter - is this principle true?
Is keeping one of the terminals of the potentiometers open (not connected) a good idea? Should they serve the purpose in this circuit?
If I want to troubleshoot, what are the test points and what are the expected voltage or other attributes I should look for?

simulate this circuit – Schematic created using CircuitLab


texts: How to find the resistor using the equivalent resistance?

texts: How would I simplify this circuit so I can find the missing resitors using equivalent resistance?


texts: AS8510 ADC Reading to Current/Voltage Measurement

texts:
I have this AMS AS8510 data acquisition IC for battery management with dual ADC (datasheet) that is supposed to measure the current, voltage and/or temperature of a 12 V battery.

I'm having a hard time converting the ADC reading of the current and the voltage measurement. I would like to be able to dynamically use any gain, whereas the shunt resistor's value is 300 μΩ. What would the generic equations be for both voltage and current?

So far, I've calculated the voltage to be:

\$V = (\frac{1.225V}{2^{16 - 1}}) * V_{ADC} * Gain\$


texts: How to determine baud rate of microchip peripheral at runtime?

texts:
I'm using a PIC24H Microchip microcontroller to communicate via UART with a Bluetooth Module.  The Bluetooth module's baud rate can be configured at runtime via software (over bluetooth or over UART) and the baud rate will change after a power cycle.

Unfortunately the only way for the microcontroller to find out what baud rate the Bluetooth module's UART is using is by asking it--over UART.

Is there a way that I can have the microcontroller test (maybe by trial and error) what the baud rate of the bluetooth module is set to?  It can only be a limited set of values and will probably be set to either 115K or 230K if that makes it easier.


texts: avr-gcc _delay_ms timings are off; ISP to blame?

texts:
I just built an AVRISP with an old Arduino Nano (ATmega328p), and I tried to flash a simple blink program onto an ATmega328 (non-picopower). The first time I flashed the program, everything worked out great — the 1000ms on and 1000ms off interval were as I expected. However, I changed the off interval to 100ms, and suddenly the period was almost 9 seconds in total — about 8 seconds on and .8 seconds off. Flashing the original 1000ms on and off intervals resulted in an elongated period as well.

I am using the Makefile from a simple blink tutorial; the only thing I've changed is the port designation and MCU. Given that, I believe that the issue lies in my ISP... but what could cause an initial success, then repeated failure? If you need any more information (header or hex dump, etc.) then let me know and I'll be happy to oblige.


texts: Reduce silver oxide battery 1.5v to 1.3v

texts:
I am looking to reduce the voltage of a silver oxide battery from 1.5 to 1.3 volt for a Bulova Accutron movement. The watch movement uses approx 4.5 to 7 micro amperes. I have used the formula for trying a resistor but cannot find a resistor that would work. I hope you guys on here can help me.

Dan the Horologist


texts: What pH sensor have a long-term use with non-calibrated?

texts:
I have a project that use some water monitoring sensors (pH, oxygen, conductivity...). But my project are facing a problem:

My device can not be touch within 3 months. And as my knowledge, those sensor above need to be calibrated after a short period of time.

So, any solution for me? Thank you.


texts:
If we are told that the instantaneous SNR at a specific frequency \$f\$  is \$\gamma\$ (We do NOT assume that the channel is AWGN but we are only interested in the capacity in bit/s/Hz at this specific frequency), can we safely say that the instantaneous capacity is:

\$C = log_2(1+\gamma)\$.

If we are further told that the the instantaneous SNR at this specific frequency is \$f_\gamma(\gamma)\$, can we say that the ergodic capacity can be calculated from

\$C_{erg} = \int log_2(1+\gamma) \cdot f_\gamma(\gamma)\,d\gamma \$.


texts: How can i get the Q operating point of the differential amplifier?

texts:
I'm working with this type of configuration: Differential amplifier, and I need to find the current for this circuit so I can have maximum symetrical swing, and for that, I need to find the operating point.
But I've searched everywhere and I'm not able to figure how can I get that point in this type of circuit.
Any kind of help would be useful, thank you so much.

here you can see the configuration


texts: LED Dimmer only using NPN BJT and potentiometer

texts:
Does this circuit looks ok?

I'm trying to make a RGB lamp with knob controls. The LED has a maximum current of 20mA. I've successfully created a working prototype of below circuit.

I'm not from electronics background (hence for me priority wise simplicity of circuit > its efficiency). I tried creating PWM using 555 but was not getting the desired result.

Combining all the answers and suggestions, does the below circuit make sense?

simulate this circuit – Schematic created using CircuitLab


texts: Identify this component with a weight inside a cylinder

texts:
This component was pulled from a device that was used to detect movement. When I first saw this part, I thought it was an electrolytic capacitor, but upon closer inspection, I found that if I shake the part, it has a small metal weight in the end (opposite of the two wires) that rotates around. I'm guessing it is some kind of mechanical motion sensor, but I'm not sure what the technical name is. I'm interested in finding its datasheet or a similar part to use for another project.

Here are a couple of pictures of it:


texts: Is there any modern video connector you can use royalties free?

texts: I would like to make several hundreds of a device with video out. It seems every video connector involves huge fees for licensing - is there anyway around this?


texts:
Could lightning discharges be harvested and stored in supercapacitor banks? Could supercapacitors withstand and collect lightning?

Lightning usually lasts for about 10 micro seconds and reaches potentials of hundred thousand volts. However, the energy levels of lightning are quite high: Several million Joules of energy.

If lightning harvesting is not practical on ground level, could aeroplanes benefit from lightning harvesters to collect electricity?


texts: Battery Array has only one side getting warm to the touch

texts:
I am working on a project that involves running a go-kart off of solar and batteries. Recently, I tested it out using just the batteries themselves and found out that my battery array (4 12 volts 20 amp/hour batteries with 2 in series 2 in series and both of them combined together in parallel) started to get quite warm only one of the series. Why is this? My guess would be the fact that I connect my motor controller leads (Plus and Minus) directly to only one set of the series banks.

simulate this circuit – Schematic created using CircuitLab


texts:
I would like to know if you have a way to call without needing a line of communication at CADENCE?

See the example in the PROTEUS software image, at the time I made the connections without needing the lines, this makes the visualization less polluted and easier to locate the components in the schematic.

I will be grateful if someone provides a link or PDF of a complete CADENCE tutorial.


texts: Strange Distortion from Second Order Active Low Pass Filter

texts:
I'm feeding a 250KHz PWM audio signal from an ATtiny85 into a second order active low pass filter:

The output is then fed into a decoupling capacitor and then into an LM324 amplifier.  The output of the LM324 is then fed into a decoupling capacitor and then into an LM386 audio amplifier. The audio generally sounds good but there is some distortion.  When I view the waveform on OUT1 I get this (the yellow trace is OUT1, the blue trace is after the decoupling capacitor):

What are the strange "drops" I'm seeing?  The top of of the waveform looks ok, but the bottom half has these drops.  This is some type of distortion, yes?  What causes this?  How can this be eliminated?

UPDATE 1:
Here's the PWM from the ATtiny85:

UPDATE 2:
I stated above that

  The output is then fed into a decoupling capacitor and then into an LM324 amplifier.

This is not correct.  What I should have said was the output of the LM324 is fed into a decoupling capacitor and then fed into an LM386 audio amplifier.

UPDATE 3:
Here's 12ms of the 250KHz PWM input:

UPDATE 4:
Here is the complete schematic:

Addressing some of the comments and the suggested solution:

I moved the Vcc for the LM324 from the regulated 3.3V supply to the +6V supply.  This did clean up the signal coming from the LM324 (i.e. the recovered audio from the PWM input), but significant distortion can still be heard.  I still need to test to see if the LM324 is failing at specific frequencies.
I added a 1K resister from the output of the LM324 to ground.  Originally I did this to address a comment suggesting that having the output float was not a good idea.  The proposed answer says (if I understood it correctly) that this 1K resister tied to ground should force the LM324 output stage into a class A amplifier, thus avoiding a crossover problem.  However, at the time this was suggested to resolve any crossover problem, it was already in place.

Is it possible that the LM324 is just a very bad choice for audio?  I've heard it has a relatively slow slew rate that causes distortion.  Should I be looking at another op amp (that works with a single +6V supply)?

UPDATE 5:

Here are the traces from the current circuit.  Yellow is the output from the LM324.  After moving the power supply for the LM324 from the +3.3V regulated to the +6V, you can see that there are no more drops (which technically resolves this question).  The blue trace is the output from the LM386 audio amplifier.  There is distortion on the bottom of the wave and it's pretty audible.  I think if I can resolve this distortion I'm good to go.   And this pretty much proves that the LM324 is "good enough" for this audio application.

UPDATE 6:

I stated earlier that the LM324 was "good enough" for my application, and this is true.  If you examine the output waveform from the LM324 at higher resolution it can be observed that the signal is "noisy" (I did not include a trace of this).  Simply unplugging the LM324 and plugging in an MC34074APG (with no other changes), substantially cleaned up the output waveform.  This may become my new favorite single source op-amp.


texts: Measurement range versus calibration in electronic instrumentation

texts:
I need to monitor temperature between -15°C and +40°C. The transducer(Pt100 probe and R/I transmitter) can measure between -25°C to 72°C. But I need the temperature transducer to be calibrated by an institute. The thing is that they calibrate between +15°C and +30°C.

Is that fine or a custom to calibrate a narrower interval than the range used? I have no experience with that and was a bit confused. Does anyone have experience with that? Should the measurement be inside the calibration range?


texts: Is there an industry standard or MIL-STD that specifies the force a connector needs to withstand before coming off a PCB?


texts:
I acknowledge that the subject line indicates a "how long is a piece of string" style question, but I hope to make it more specific below.

I have a "current transformer" (CT) purchased as part of an Efergy energy monitor unit. It appears to be a split core ferrite that closes around the primary (live) with a large number of turns on the secondary. The secondary has a 2.5mm audio jack attached for sampling. I assume there is a resistor inside the plastic case of the mini-CT to enable a voltage drop across it (facilitating sampling).

No wires have been cut to attach the mini-CT, it is simply coupled to one live wire. The live wire is at 240VAC RMS and carries a current of several tens of amps to a household.

Is it safe to touch all the connectors of the audio jack, with my feet touching the ground and the mini-CT attached around an AC live wire that's currently drawing a current?

Would the advice of the previous sentence change if I reduced the ratio of  secondary turns from 1:2000 (I don't know if this is the true number, I'm just guessing) to 1:10 or 1:1?


texts: Confused about the input voltage in specification sheet?

texts:
I am quite new to arduino .Something in the specification list makes me confused :

I am confused about the following :

Input Voltage(recommended)7-12V
Input Voltage (limits) 6-20V
Operating Voltage : 5V

Is  Operating Voltage is the voltage that is used to power up the board ?
If So,What does Input Voltage(recommended) and (limits) refer to? Are they regular analog input voltages?

Any Help regarding "Operating Voltage" and "Input Voltage" is highly appreciated !


texts: Finding Fmax in FPGA design without adding extra cycle

texts:
I'm trying to find the Fmax of my VHDL design in Quartus II. I know that you need to have a register-to-register path for finding the Fmax. However, when I register the input, another cycle is added. I want the code to be 1 cycle and still show Fmax.

Code with registered inputs:

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity generic_RBSD is

    generic(
        BIN_WIDTH : integer := 4
    );
    port(
        bin_input : in signed(BIN_WIDTH-1 downto 0);
        RBSD_output : out STD_LOGIC_VECTOR(2*BIN_WIDTH-1 downto 0);
        clk : in STD_LOGIC
    );
end entity;
architecture behavioral of generic_RBSD is
    signal a : signed(BIN_WIDTH-1 downto 0);
begin
    process(clk)
        variable bin : signed(BIN_WIDTH-1 downto 0);
        variable RBSD : STD_LOGIC_VECTOR(2*BIN_WIDTH-1 downto 0);
    begin
        if rising_edge(clk) then
            a <= bin_input;
            if bin_input(BIN_WIDTH-1) = '1' then
                bin := -a;
            else
                bin := a;
            end if;
            for i in 0 to BIN_WIDTH-1 loop
                if bin(i) = '1' then
                    RBSD(2*i+1 downto 2*i) := "11";
                else
                    RBSD(2*i+1 downto 2*i) := "10";
                end if;
            end loop;
            if bin_input(BIN_WIDTH-1) = '1' then
                RBSD := not RBSD;
            end if;
        end if;
        RBSD_output <= RBSD;
    end process;
end architecture;

Without registered inputs (works, but doesn't show Fmax):

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity generic_RBSD is

    generic(
        BIN_WIDTH : integer := 4
    );
    port(
        bin_input : in signed(BIN_WIDTH-1 downto 0);
        RBSD_output : out STD_LOGIC_VECTOR(2*BIN_WIDTH-1 downto 0);
        clk : in STD_LOGIC
    );
end entity;
architecture behavioral of generic_RBSD is
    signal a : signed(BIN_WIDTH-1 downto 0);
begin
    process(clk)
        variable bin : signed(BIN_WIDTH-1 downto 0);
        variable RBSD : STD_LOGIC_VECTOR(2*BIN_WIDTH-1 downto 0);
    begin
        if rising_edge(clk) then
            if bin_input(BIN_WIDTH-1) = '1' then
                bin := -bin_input;
            else
                bin := bin_input;
            end if;
            for i in 0 to BIN_WIDTH-1 loop
                if bin(i) = '1' then
                    RBSD(2*i+1 downto 2*i) := "11";
                else
                    RBSD(2*i+1 downto 2*i) := "10";
                end if;
            end loop;
            if bin_input(BIN_WIDTH-1) = '1' then
                RBSD := not RBSD;
            end if;
        end if;
        RBSD_output <= RBSD;
    end process;
end architecture;


texts:
I have this old Nikko Tiger 2 RC car I've been playing around with. At first I disassembled it and played around with the parts and my parts (motor controller++).

But then I asked myself, can't I use the parts already in there? And put the end of the antenna of the RC car (not the remote controller) into my arduino? Making the arduino produce the signal for the various commands (forward, backwards, steering).

Is it possible? The remote controller is a simple, two throttles: up/down and left/right. It states that it operates on 27MHz.

Could I do this in two steps:

1: open up the remotecontroller, plug the antenna to the arduni and record the various commands

2: plug the antenna of the car to the arduino and make the arduino produce the signal for the various commands?


texts: Switching power supply using faraday cage and EMI protection?

texts:
Several switching power supplies in the market use this kind of cages to protect the circuit, however, i have this question,

A) Is this used as a faraday cage due to the high frequency used by it?

B) How important are EMI filters for this kind of power supply?


texts: Four power supplies in parallel to a bacon light?

texts:
I have four machines at 24vdc and would like to have one light(e.g. tower) on when either machine is working or when all are working. This to happen, the light is connected independently to each ps, in this case all four ps become connected in parallel.
Now the question is how would all four ps react to the light and to each other when let's say all four are powered up? It is also the case where all four ps's are not exactly 24vdc(one is 22.5). I have tested with #1 machine first and the light works fine; when connected #2 unit to the light, so two machines in parallel (but #1 was off, no pwr) the unit failed and I had to reboot. Here I put one forward diode on #1 machine on the +24vdc line and  tried again. This time there was no problem running #2, however #1 was still off. And here I stopped and looked for help online, but would be glad to see your input on this situation.


texts: How to connect multiple star points and ground zone together on PCB?

texts:
I have designed this PCB layout for an all analog Op Amp circuit plus LM386 for headphones pictured right in the yellow section:

Are we allowed to have multiple star points, as I have on the PCB?
And is it OK to connect them all to the ground plane, as I have on the PCB?


texts: Two 2.4GHz radio modules (XBee+Bluetooth) on same PCB. How to minimize interference?

texts: I'm designing a PCB with XBee radio module and a bluetooth module (RFDuino SMD with XBee 2mW Radio). Since both of these modules are using 2.4GHz, are there any special consideration about how to place them on the PCB to minimize radio interference? Is it a good idea to place the XBee on top of the BLE module to save space?


texts: Determine the frequency and on time of two coupled ne555

texts:
I've the following circuit:

I use it as a voltage controlled pwm generator. My question is, how can I find the frequency and on time of the PWM. I tried changing all the resistor and capacitor values and they all change te frequency so what is the relation?

I thought maybe I could use:

$$\text{f}=\frac{1.44}{\text{C}}\cdot\frac{1}{\text{R}_1+2\cdot\text{R}_2}=\frac{1.44}{9\cdot10^{-9}}\cdot\frac{1}{20\cdot1000+2\cdot537}=7592.29\tag1$$

So that is not true :(


texts: How to lower the RPMs in small a DC motor

texts:
I make Christmas ornaments for a living.

I have an idea that is a tube that is 18" tall, 6" diameter.  I need it to slowly spin at around 5-10 RPM. Please keep in mind that I need this to be as cheap as possible. This design is versatile and can accommodate any method. It will spin easily because it will be spinning on a needle point, and there will be a 2" high hollow base for any parts. I have plans for using gears or pulleys, but I was hoping that I could alter the speed of the motor somehow instead.

Thanks for any advice and please keep in mind that I need to do this as cheap as possible.


texts: RF link wireless trigger (press/hold) with no mcu

texts:
i have a talking birthday card to trigger from distance of 20-100m (line of sight).
what would be the easiest way to send press/release (and hold) commands?

i expect a false positive here and there.
this project is for a layman workshop, so i want to keep it simple
was looking at 315Mhz link tx/rx kits. selling for a few $ on the net.


texts: Sampling Frequency of a pulsed radar signal

texts:
I'm new to radar. please excuse my question if it doesn't make sense to you.

In a pulsed radar signal, why is the required sampling frequency "2 times the inverse of pulse width" instead of "2 times the carrier center frequency"?

Consider a 100 ms pulse width and a 1000 Hz carrier frequency, i.e. there are 100 cycles of sinusoidal waves per pulse width.

If I use a sampling frequency of 2/(0.1 s), what would I get in the spectrum plot?

Also, is this sampling frequency (2*1/pulseWidth) the same as the fast time sampling frequency?


texts: Does a Gilbert cell have automatic gain control?

texts: Just wondering, I need to demonstrate that it does have automatic gain control for  project... paranoid me just wants to make sure!


texts: Can I use this opamp as a buffer for a given input range and supply voltage?

texts:
I'm planning to buffer a 0-10V DC signal coming from a potentiometer windvane.

I want to use this opamp for the purpose and the opamp will be powered as single supply with 12V Vcc.

Can I use this opamp for 0-10V inputs as a buffer aka unity gain? I'm worried about CMRR issues and Im not able to interpret that for this scenario.

Alternatively I have this opamp as well.


texts: Optical pulse sensor not producing a clean TTL pulse

texts:
I have two of these optical pulse sensors monitoring LEDs on my electric and solar meters - Optical Pulse Sensor - Github
The first sensor outputs nice TTL pulses at 5V, the second sensor outputs pulses at just over 1V and is very noisy and has weird blips in (see scope picture below).
I tested both sensors using a breadboard with various LEDs but they always produced nice looking pulses, so it must be something to do with the way the LED on the solar meter is blinking. I don't understand the circuitry inside the sensor to know what could cause it to output this.
Both sensors are connected to the same Raspberry Pi using the same 5V and GND with each of their pulse/data lines going to a separate GPIO pin.
Any help is much appreciated!


texts:
How are or were vias made commercially?

Wikipedia (http://en.wikipedia.org/wiki/Via_(electronics)) mentions
"The hole is made conductive by electroplating, or is lined with a tube or a rivet"

Can anyone provide more details on these processes, with an eye towards replicating the process? (I realize the standard DIY way is to thread some single-core through and solder it. That seems relatively slow and not amenable to automation).


texts: Is it possible to reject noise traveling on the outside of a coaxial transmission line?

texts:
Say I have some ordinary coax between a receiver and an antenna. That coax will have three currents in it:

the desired signal
an exactly equal an opposite current on the inside of the shield (really, also the desired signal)
noise on the outside of the shield

Now if this were a balanced transmission line (not coax), I'd connect the pair of conductors to a differential amplifier, which would reject common-mode voltage. I'd be sure the impedance of each side is equal, so that common-mode currents create only common-mode voltages, so my common-mode voltage-rejecting differential amplifier effectively also rejects common-mode currents.

But this is just ordinary coax, with only one center conductor. The impedances of the shield and the center conductor are not equal. Although the signal is trapped inside the coax by the shield, can I maintain this separation of currents when the coax enters my receiver circuitry? In other words, how do I provide a reference for my receiving circuitry that isn't affected by the noise currents (3)? Or, is that not possible?

Note that I'm not asking about alternatives to coax, or other types of coax with multiple shields, etc. I'm also not very concerned about non-ideal noises introduced into the coax by an imperfect shield, etc. A practical example of the situation of concern would be that I have an antenna connected to a receiver by some coax, and I want to receive the signal from the antenna, but not the signal from the coax shield (which can also make a pretty good monopole antenna).

simulate this circuit – Schematic created using CircuitLab


texts: Can I dip a soldering iron in water to cool it down?

texts:
I have a cheapo soldering station (Duratool D02265). It is fine for what I need. But, I often want to swap the tips round quickly, without waiting for ages for it to cool down!

I was wondering:
 Can I dip the end in water (without destroying it!) to cool it down quickly (Just to the top of the nut, so I can undo the nut and carry on working)?

Of course I would turn it off first!

Here is a picture of the soldering station and the tip (Its cheap and rubbish, I know!)


texts: STM32 systick interrupt is not triggering

texts:
Please someone help me with my code. I am newbie and trying to turn off LED inside systick handler. I tried with GDB but systick handler is never triggered. What am I missing?

.section interrupt_vector, "a", %progbits

.word 0x0
.word reset_handler + 1
.org 0x3C
.word stk_handler + 1

.section interrupt_handler, "ax", %progbits

reset_handler:

//enable GPIOA

LDR R0, =AHB1ENR
LDR R1, [R0]
MOV R2, GPIOA_ENABLE
ORR R3, R1, R2
STR R3, [R0]

//configure GPIOA_MODER

LDR R0, =GPIOA_MODER
LDR R1, [R0]
MOV R2, PIN5_GPIO_MODER
ORR R3, R1, R2
STR R3, [R0]

//enable systick

LDR R0, =STK_LOAD
MOV R1, STK_LOAD_MASK
STR R1, [R0]

LDR R0, =STK_VAL
MOV R1, 0x0
STR R1, [R0]

LDR R0, =STK_CTRL
MOV R1, STK_CTRL_MASK
STR R1, [R0]

//Turn LED on

LDR R0, =GPIOA_ODR
LDR R1, [R0]
MOV R2, PIN5_GPIO_ODR
ORR R3, R1, R2
STR R3, [R0]

LDR R0, =main + 1
BX R0

stk_handler:

LDR R0, =GPIOA_ODR
MOV R1, 0x0
STR R1, [R0]

LDR R0, main + 1
BX R0

main:

nop
b main


texts: Reliability of edge connectors for production

texts:
I'm looking for an 6 pin .1 standard edge connector to program for production my board without any connector. And I cannot find the number of cycle they can support.

Does anyone has used such connector for production ? In this case which one ?
I only managed to find on .05 sullins connector that they support 500 min cycles


texts: How does Rühmkorff induction coil start and periodically produce sparks?

texts:
I found the following pictures and equivalent circuit of the Rühmkorff induction coil:

Can someone explain the operating of this coil in a step by step fashion?


texts: Maximum allowable ripple current and surge current for tantalum capacitor

texts:
I use two 10uF, 20VDC tantalum capacitors in parallel as decoupling capacitors just after the battery connector. At the moment the battery is plugged in, one of the capacitors sometimes burns out (not always, about 1%).

I measured the surge current of the capacitor when it is powered on by the battery, and it is up to 4A as the following screenshot shows.

Yellow - The voltage of the capacitor, Green - The current of the capacitor

I guess the surge current may be the reason for the burning out, but I cannot find any data about the maximum surge current the capacitor can withstand.

The questions are:

How to estimate the power-on surge current of a capacitor? If its ESR is 5ohm and the maximum battery voltage is 8.4V, then the surge current is 8.4/5 = 1.68A? Then how can I know if the capacitor can withstand that?
There is a "maximum allowable ripple current" parameter from the datasheet. It's a smaller value, such as 122mA at 25 degrees celsius, 100kHz. When should I refer to this parameter and promise not to make the current exceed it?
If the surge current is the reason for the failure, how should I choose a tantalum replacement?


texts: Is there something called as inrush current at the output of the DC-DC regulator or LDO

texts:
I am using this LDO to step down from 14V to 5V with a maximum output load current of 150mA.

The above is the schematic of my LDO.
I want to measure the inrush current of the LDO.
But since I have an output capacitor of 1uF, I think the output capacitor will also contribute some inrush current.
I want to understand about inrush current. I have read and understood that the inrush current is caused by uncharged capacitors getting charged during start-up. Hence, the high inrush current during starting of the power supplies.
Question 1 :
My 1uF is placed at the output. So, when I need to measure the inrush current of the LDO, should I measure the current at the input pin 1 of the LDO or at the pin 8 of the LDO during start-up? (I think both scenarios are not that different, since in LDO, the input current is same as the output current as LDO just has an internal pass MOSFET or transistor- Am I correct?)
I have a doubt in this too. To measure the exact inrush current, should I take a wire (very low resistance) from the output pin 8 of the LDO and connect it to the 1uF capacitor and measure the current through this wire using a current probe and note it down as the inrush current? Is this approach correct?
Question 2 :
In DC-DC converters, for example, buck converters, say TPS54260, the input inrush current and output inrush current are different, right? In this case, how to measure the inrush currents at the input and output?


texts:
I need to read the internal flash of RX63N MicroController multiple times. It will always be the same data block. I was concerned about the life of the internal flash, wearing out etc. I read that NOR flash is durable. Hence would like to know what type of flash is used in RX63N.

I could not find any information about this in datasheet R01DS0098EJ0180 (Rev.1.80, May 13, 2014)


texts: Why would any smartphone need an ambient light sensor if it already has a front-facing camera?

texts:
Why would any smartphone (e.g. the Samsung Galaxy S5) need an ambient light sensor if it already has a front-facing camera?

Surely it requires time and money for the engineers to design an ambient light sensors into a phone's motherboard.

When light sensing is needed (e.g. for automatic screen-brightness adjustment), why doesn't the phone simply do the following every ten or twenty seconds?:

Power up the front-facing camera.
Capture an ultra-low-resolution photo.
Analyze it in order to see how light or dark the room is.

This could all be done automatically by the phone's operating system.


texts: How to ensure the two schematic diagrams are equivalent?

texts:
I've tried copying the schematic diagram of a typical circuit from the datasheet, but I'd like to ensure the correctness of each connection. Is there a way to somehow match one schematic diagram against another?

If simulation is the only thing closest to such a test, which simulation is most useful?

Thanks


texts:
I don't understand how FPGA can be used to accelerate an algorithm. Currently I'm running a time consuming real time algorithm on a quadcore laptop so that four computations can be done in parallel.

I have been recently alerted that FPGA may yield even better performance. I don't understand how that works. Can someone explain how FPGA accelerates an algorithm and if I should switch to a Xilinx or Altera FPGA solution or keep performing the computations on my quadcore laptop.

Additional Details: The algorithm runs 20 artificial neural networks using inputs fed in through the wavelet packet transform

Thank you all for the great answers.


texts: Are designation of voltage current quantities with upper and lower case letters universal

texts:
Below shows designation of voltage current quantities with upper lower case letters:

RMS value for instance is indicated with upper case letter with small subscript.

Is this above table universally accepted? Is there a standard?


texts:
I am wondering if an ATMEL micro controller such as an ATMEGA8 or ATTINY2313 has libraries to interact with a computer (windows OS) over USB? If so is there any premade libraries that does the bulk of the coding work for me? I would be using the Atmel Studio IDE for programming. If possible is there separate libraries for keyboard events/interaction, and raw USB interaction which software running on the OS can capture. A bonus would be an example of how to capture raw usb messages from my device in simple software on windows.

My next question is, is it possible to run native windows code directly from the micro controller. I am lead to believe it is not possible since in order to interact with the windows API which I want, you would need to have a windows compiled binary with the API library on your device and somehow run it from memory or the like.

Thanks for any answers you can supply me with.


texts:
I have the following double band-pass op-amp. The cut-off frequencies are 34 and 50kHz.

How can I calculate the slope of the gains around the cut-off frequencies? I want to know at which frequency I have -3dB.


texts: Why does a phase shift happen in the demodulated AM signal using envelope detection?

texts:
I was studying  AM signal demodulation using envelope detection with the circuit shown below.
In the book it says the low pass filter part is called a post-detection filter and that this filter causes a phase difference between the original signal and the output signal.
I don't quite grasp why this phase difference happens.
Can someone enlighten me?

The text from the book:


texts: Automatically renumbering element parts in Eagle

texts:
I have a circuit in Eagle, and say that counting from left, I have R1, R2, R3, then between R1 and R2 I'm adding a new resistor, it will be named R4. I will end with (looking on the circuit) R1, R4, R2, R3.

It's not ordered.

I would like to keep elements ids (separately for each element type, e.g resistors, capacitors) in order from lowest to highest (counting from left). Is there a script or settings in eagle that will do it automatically for me?


texts: Noise figure of Microwave radio receiver

texts:
I always wondered why ADC is not considered for noise figure measurement in receiver chain? Do ADCs will not have much impact on noise figure in signal processing?

How to derive a Noise figure spec for receiver in relation with the selected ADC?


texts:
I experienced the same as described in this question: A AD8603 is used as voltage follower to amplify the pH sensor signal to a microcontroller. As this opamp has a single supply and thus cannot output a negative voltage, the pH sensor is connected between a 600mV reference and the AD8603 non-inverting input (with a 1M resistor in series, as described in an Analog Devices application note).

For power supply I used vigortronix switched mode power supply modules that accept 230VAC as input and 5V for output.

Everything works as expected, except, when the pH sensor comes in contact with the liquid to be measured in a real production environment the output of the AD8603 clips to its supply voltage. The liquid (for the most part just water) runs through metal pumps that are connected to earth, so the potential of the liquid is about the same as the earth potential I'd say.

I was able to reproduce this behavior on my desk by holding a wire connected to earth in the glass with the testing liquid (pH buffer 7.0).

I replaced the vigortronix module with a simple linear power supply: transformer, rectifier, buffer capacitors and 5V voltage regulator and the problem is almost gone. I say almost, as I see a tiny fluctuation (0.1 pH at most) in the measured pH when I hold the wire connected to earth in the liquid but I'm not sure if this is caused by the wire.

I don't understand what is going on here. This circuit has no connection to earth, it is completely floating. I cannot connect earth to the ground of the circuit as that would short circuit the reference voltage (pH sensor electrode is connected to earth via liquid).
But even if that was not the case, connecting earth to ground will introduce the ground loop.

What are switching power supplies doing that can cause this behavior?


texts: Why do surface mount mosfets have the heat sink pad on drain rather than source? (N channel)

texts:
On many surface mount power N-mosfets I have seen that the large pad is electrically the drain pad.

Wouldn't it make more sense to heat sink to the ground plane, where you probably already have a lot of copper? It seems like making the "heat sink pad" drain just increases the amount of total copper/used space on the board. Why design them so that you have to add an additional, or perhaps many, separate large fill(s) for heat?


texts: Which register holds the final arithmetic and logic results?

texts:
This Wikipedia page  says

  an accumulator is a register in which intermediate arithmetic and
  logic results are stored.

So which register holds the final result?


texts:
I am trying to figure out the Inductance used on this PCB. I know it's value but need to understand what type of inductor it is and other things so I can order it.

The code on it 100 M5D yeilds no results. The value from schematic states it to be 10uH.

Any help understanding the packaging/type/current etc. will be very much appreciated.


texts: A question about the sound of corona discharge

texts:
In my collage, We were doing an experiment of the air's Breakdown voltage . At the end of the experiment we were listening to the sound of corona (electric partial discharge). The power supply has the ability to vary voltage. The more the voltage increases, The higher the tone of the sound.

As you can hear in this video: https://youtu.be/KVANbkI8AmM?t=8m23s (At 8:23)

I know that the fundamental "hum" frequency will be twice the electrical frequency due to Magnetostriction effect. The frequency of the sound  = 100 Hz (in Egypt). So, Why does the tune become higher while rising the voltage?

One more questions, What causes high harmonics in transmission lines? or Why do we hear frequency higher than 100 Hz?


texts: Stepping down 12 V to 9 V with minimal waste of energy?

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I have a 12 volt gel cell battery that outputs 13.6 volts when fully charged. I wanted to use it to provide backup power to my modem and router (both of which are supposed to draw a maximum of 0.6 A at 9 volts). I've looked at circuits using LM7809 voltage regulators, but those still waste power.

Now my question is, is there a more efficient way to step down this 12 V source to 9 V for these devices. Or should I even worry about efficiency at this small a scale at all?


texts: How to calculate maximum power when value of load resistance is unknown?

texts:
Once again same circuit and same voltage source / current source and resistances. However now I need to calculate the maximum power that is consumed by the RL. How do I do that, and most importantly when I don't have the value on the load resistor?

Here is the shematic of the previous problem I solved (Thévenin equivalent):

simulate this circuit – Schematic created using CircuitLab

And the new question is this one:

Note:  I1 should be 2 mA.

And here is the link to the question I submitted before this one:

How do I calculate load resistance?


texts: Decoupling high current load and 5V regulator

texts:
I have a 12V DC input from a power adaptor. A LM7805 5V regulator takes this as an input and powers an MCU and some other digital circuitry that will eventually drive a relay through a high-side load switch.

I'm using the recommended capacitor values from the data sheet of the 7805 on both the input and output side.

Below is a simplified version of the real circuit:

simulate this circuit – Schematic created using CircuitLab

I'm worried that when I drive the relay that the sudden increase in power draw (up to 3-4 A) may cause the input voltage to the 7805 to drop and possibly causing the MCU to BOD reset. Should I add a larger electrolyte decoupling cap parallel to C2 to mitigate this, and if so, how would I go about determining how big it should be. Do I need to take some steps to prevent reverse polarisation of it by using diodes? I've never used electrolytes before (although I understand how they work).

Are there any other considerations I should make in regards to the 12V part of this circuit?

Is it worthwhile to add a capacitor between the marked +12V node and the the ground wire after the relay?


texts: CadSoft Eagle polygon won't reach pads in Molex library

texts:
I'm using the Molex 5569 library in CadSoft Eagle. When I create a polygon, it won't reach the pads at all. The problem occurs only with components from this library.

Have a look at this screenshot as well:


texts: Powering 10watt light bulb for 24 hours using solar power

texts:
I am a total noobi to solar power and even electricity so I apologize if I am asking a silly question.

Imagine I have a 10 watt light bulb which I want to leave on for 24 hours a day.  Will I just need a solar panel which can generate 10 watts?  Or will I maybe need a 20 watt solar panel, so 10 watts is used to power the 10 watt light bulb and the other 10 watts gets stored into a battery to power the light bulb during the night for 12 hours?


texts:
I am implementing a device which communicates on Profibus DP. In order to get the communication with my Siemens S700 PLC to work, I have to reverse the order of the 'A' and 'B' differential signal leads.

The profibus communication is implemented by a Profichip VPC3+S. I am using an ISO1176 RS485 which provides an 'A' and 'B' connection.

Any ideas why it is 'backwards'?


texts: How to read pinout of this SPDT relay G8N-1F

texts:
Introduction:

The direction indicators of the car (Honda FR-V) are not working anymore. I managed to get the ICU (integrated control unit) out of the fuse box beneath the steering wheel. Hell of a job in such confined space. There are 2 relays of which I think 2 are for the direction indicators. Anyway. I suspect the relays are at the end of their life time (already after just 140,000 km on the car!!) and wish to replace them.

Question:

This is the datasheet.
The relays in question is an Omron G8N-1F.
How do I read this schematic? It is a SPDT relay. Which pins get connected when the operating voltage of 12Vdc is applied at what pin? Probably a newbie question. From what I read pin 4 and 1 are connected as normally closed. When current is running from pin 2 to 5, pin 1 gets connected to 3. Am I right? Thanks so much.


texts: How are the positions of matching network elements determined for RF power amplifiers?

texts:
I asked an electrophysicist and he gave me a wishy washy experimental answer. Let me provide an example.

Let's say we want 50 ohm input and 50 ohm output from some particular wideband amplifier. The amplifier is not internally matched. I have full design freedom in terms of PCB traces and component selection. I also have access to network & spectrum analyzers.

I'm afraid of the answer being: "Hook it up to a network analyzer and season to taste"
I've completed my undergrad and this type of designing was never mentioned. Assume I don't have the S parameters of the IC.

For reference, assume I'm using this transistor tuned for the 2.4GHz band


texts: Can dead mains-to-12V lighting transformers safely be left permanently connected to the main supply?

texts:
Transformers for 240V mains to 12V lights: I have several dead transformers (not sure what type exactly) hooked up in parallel to a domestic mains circuit. I can't easily get at them to change them, they're in a ceiling & I don't want to rip the whole ceiling down!

However, I can add new transformers (a spot of key-hole surgery) to the circuit, effectively bypassing the dead ones, and it's easy to rewire (new) lights to the new transformers. The old, dead transformers remain in parallel with the new ones. I will put the old12 V ends into connectors, for safety and tidiness.

Q1: What are the problems of simply leaving the old ones where they are in parallel with the new - any safety issues?
Q2: Could the demise of the old transformers have been caused by replacing the switch with a dimmer - they worked initially. (The new transformers are all dimmable).


texts:
Can I solder back together a single broken copper winding wire in an electric washing machine motor?  This is the motor: http://www.repairclinic.com/PartDetail/b5p11/Whirlpool-Washing-Machine-Drive-Motor/661600/675936?modelNumber=LSR7233EQ0&ss=a11b5d112106&mr=1 .  The culprit is in the topmost winding in this picture, closest to center top, near where a screw attaches the capacitor bracket to the motor housing. This is an induction motor, with no brushes, and the wire is in the stationary portion of the windings, not the inner spinning portion.  I have the motor out of the machine, which fills with water but only hums during agitate and spin cycles & won't drain.

I know how the break happened and can resolve that problem.  Years ago I upgraded the capacitor on this machine because I was using it off-grid with a generator and it needed just a little more help to start the demanding cycles. That upgrade worked fine, except that the bracket holding the capacitor was not quite large enough to secure both ears of the bracket under the screw on the motor housing.  I should have made another bracket that fit the new capacitor and pinned it down tight, but did not.

Now, in a different home with mains power (and after a couple years of use), the bracket slipped a little with the motion of the machine. The corner of the unpinned bracket made contact with one wire in the winding, which breached that wire. Here again, I should have re-installed the original capacitor, but did not, and it worked just fine.

I plan to replace the original working capacitor, which I still have, and whose diameter is slightly smaller allowing it to fit properly in the bracket and allowing both ears under the screw.The position of the broken wire makes soldering it back together in 20 minutes VERY tempting.  Worth trying?  I found plenty of recommendations to replace the motor, which is $161 plus shipping at repairclinic.com.  I found this hopeful note on http://books.google.com/books?id=lp3f5_JHrggC&pg=PA24&lpg=PA24&dq=can+a+broken+armature+winding+be+soldered?&source=bl&ots=wGOwUearAB&sig=4jC4Utvw7mmKZj_iggZMsfvYKLg&hl=en&sa=X&ei=zLdpVMHxKZDDiQLJwYDYBg&ved=0CCYQ6AEwAQ#v=onepage&q=can%20a%20broken%20armature%20winding%20be%20soldered%3F&f=false . This describes such a repair on a (much smaller, I assume) model train motor.  I'm a fairly competent solderer. Is this worth trying?


texts:
I need to verify the resistance on a HV transformer that receives 208v single phase through terminal 1 and 2, or 240v through terminal 1 and 3 and delivers 4000v through terminal 4. As per the specifications, the resistance between t1 and t2 needs to be somewhere between 0.8-1.1 ohms(obvious the transformer has to be completely disconnected of power for the test). i tried a few clamp multi testers and none seemed to deliver a proper reading, some take a little long to come to a reading and oscillate up and down, bottom line is, i almost never have a proper reading.
question, what multi tester (preferable a clamp style, because i need it for other applications) would be the proper one for the call.
thank you very much in advance.


texts:
I read that galium nitride and silicon carbide are piezo materials.Does this cause some problems? I can imagine that unwanted piezoelectricity directly in the circuit path would cause some kind of distortion or noise.

Can this be modeled as some kind of parasitic voltage source?
How strong is this effect? I know some piezoelectric materials are alot more piezoelectric than others,is SiC and GaN only extremly weak piezoelectric materials ,so weak that it can be ignored?


texts:
I'm building a furnace controller that should hook up in parallel to a home thermostat. The schematic of a thermostat-controlled furnace (omitting non-essential components) is below (Fig.1):

I would like to replace the switch (external thermostat unit) with a triac. The triac (T2) is controlled by a digital circuit (X1), which gets power from a wall-wart adapter (Fig.2):

If a user plugs in the wall-wart unit other way around, i.e. L and N on TR4 would be swapped - what would happen? I presume short-circuit. How can I avoid it? Except using optotriacs and polarized plugs?


texts: Charging Battery via solar panel to power a push action solenoid

texts:
This is my first project ever, I'm running into some problems with the power supply stage, I hope you could help! I want to power a solenoid (12v/2A), which will get its voltage from a battery (12V/3000mAh) connected to a Solar Panel (12V/430mA – 5.2Watt). I would really appreciate it if you could show me a schematic design to this simple circuit. To sum my idea up  [solar panel >> battery>> solenoid]. Thanks in advance!
components used:
Solar panel: Mini Solar Panel 12V/430mA – 5.2Watt,
Solenoid: JF-0826B Push Action Type Electric Linear Solenoid 12Vdc,
Battery: Lithium-ion Super Rechargeable Battery Pack (12V, 3000mAh)
I would like to connect the solar panel directly to the battery:
Can you please explain why it is a bad idea to connect the solar panel directly to the battery ?


texts:
I am designing a twin-T filter, which has a cut-off around 4.5 MHz. In this filter, both R1 and R2 must be 2 x R3. C1 and C2 must be half of C3.

I have selected R1 = 10k and C1 = 3.6pF and that gives me a cut-off around 4.42 MHz. But I need to find a resistor, R3, which is exactly half R1. I could put two resistors in parallel, but then I effectively double the parasitic capacitance, which might interfere with the filter. Also, I need to find a C3 which has a value of 7.2pF which is not a standard value.

What do you look for when selecting components which must be matched?
Are there packages of resistors, capacitors, etc. available which are guaranteed to match each other within x percent?
If I am looking for precision components, should I be looking for precision resistors more than capacitors?


texts: Motor specifications - how to compute allowable running time for power levels between the continuous and peak specs?

texts:
Say a motor is rated for 20 N·m continuous torque, and 35 N·m peak (peak = for no more than 30 seconds). Alternatively it may be specified at with continuous/peak currents, but if the motor efficiency is good overall, then this is almost an equivalent definition.

Say that I want to run the motor producing 25 N·m for some time. Is there a general mathematical model that approximates the safe run-time at that level? It's certainly more than 30 seconds, but I'm unsure how to derive an approximate value.

More specifics: it's a 3-phase brushless motor, and it does have a temperature sensor. However using the temperature alone (and disregarding the specs) does not seem to be a good approach. E.g. 30 seconds at 35 N·m does not heat it very much, and it doesn't get even close to the max temperature per specifications. I'm also constraining myself to the typical application RPM ranges, e.g. 50 to 100% of the rated speed.


texts:
I have an RS232 input and 2 audio lines that I want to switch to either computer A or computer B depending on the state of a physical toggle switch. Can anyone point me in the right direction of what parts I'd need and how to wire this exactly?
I attached an image for clarification.
Thanks!


texts:
I'm working with an MCP37231/21-200 that requires a differential input for the clock. I need to know if I can use an LVDS input to drive my clock.  The output clock is specified to have LVDS capabilites, but the input clock does not state that.

From my understanding, LVDS inputs have a differential voltage of ~350mVpp, so it should work in this application. I'm also concerned about the common-mode voltage from the LVDS pair and the internally-generated common-mode voltage.

Would using an LVDS type signal be appropriate?


texts:
My transistor is overheating when the MCU turns the fans on. How do I fix this?

simulate this circuit – Schematic created using CircuitLab
The MCU has an output of 12V.


texts: How to stop false triggering of limit switches by external electrical discharge?

texts:
I have a self built 3D printer type system with some limit switches like the ones shown below. The switches themselves are just glued onto a PLA 3D printed bracket which clamps onto an aluminium frame. I've set up my code so that when the limit switch is hit the axis steps back off the limit switch a certain amount of steps. When I touch the frame with something else that is made of metal the limit switches trigger and the printer axes start moving which I of course don't want. Using a lighter near to the machine or moving a soldering iron near to the machine, and even once lighting outside also triggers the limit switches. My complete circuit diagram is shown below with limit switches at the top. With the STM32 I just have each limit switch connected as an external trigger.
What can I do to stop the false triggering from occuring?


texts:
[![I am having problem understanding reversed biased pn junction as the explaination provided by my book or any other source about flow of current in forward biased condition seems equally applicable for RB conditions also i.e. current should flow in both conditions.

Read the explaination of my book it say,in FB electrons and holes combine near the pn junction and cease to exist and at the same time a covalent bond breaks near the positive terminal of battery in p region,of which electron travel to the positive terminal of battery and hole towards the junction and at the same time an electron releases from negetive terminal of battery and into the n region hence completing the circuit.

Now what I am saying,apply the same rules in RB and current will flow regardless of biasing.As in RB postive terminal is connected to N-type and negetive to P-type and holes in p-region and electrons in n-region are pulled away from the junction.Now what should happen is electron from negetive terminal of battery should combine with holes in the p-type and a covalent bond break at pn junction,of which electron should travel to the n-region and electron present in n-region should move to positive terminal of battery and hence completing the circuit.So where is the catch. ][1]][1]

[1]: https://i.stack.imgur.com/nRgY8.jpg


texts: What battery and solar panel voltage for Arduino Uno weather station?

texts:
I'm trying to design a weather station with an Arduino Uno using rechargeable batteries and a solar panel. I'm unsure about the specifications of the batteries and solar panel: do I need a 9V battery and a 9V solar panel or 2 x 4.5V batteries, etc? What would be the most efficient setup so that the unit is self sustainable?

In the country I live in there isn't a whole lot of sun each day, does this change the kind of panels I need?


texts: How to 'Shift in Parallel' in a shift register?

texts:
I am trying to design a basic calculator that can add, sub, mul and div with Logisim. To store the operands I am going to use shift registers. I have recently learned about them and I understand what is serial input and parallel load. I also know how to shift the bits. I have copied this universal shift register from my text book. (Digital Design by Morris Mano)

The calculator will work on 4 digits only. That's why I have combined 4 Universal Shift Registers in the following way

Here, every time I shift the value (Left or Right) the register shifts only 1 bit. What I need is to be able to shift 4 bits at a time. Because I am storing my digits in BCD, so I need to be able to move all the 4 bits to right or left together on a single clock pulse.

I have searched this on google and all I could find were:
Serial In Serial out Shift Register,
Serial In Parallel out Shift Register,
Parallel In Serial out Shift Register,
Parallel In Parallel out Shift Register.

But all these registers can shift only one bit per clock pulse. So, to be able to store my BCD representations, how can I shift the bits in parallel (4 bits at a time) ?

Or should I somehow control the clock to make it pulse only 4 times? (If yes, please explain me how)

Please mention if there is a better way to store my operands.


texts: How a boolean function is made for a circuit?

texts:
I studied the Boolean algebra and the Boolean function as they can be expressed as sum of minterms or product of maxterms.
But what actually the fuction is and where it came from? As we only simply take some of minterms and find there sum resulting in a specific  boolean function..for example we take a function \$F(x,y,z)=\sum (0,2,4,5,6)\$
which is \$F(x,y,z)=z'+xy'\$

But where it came from? Why we take only 0 2 4 5 6 terms?


texts:
I am trying to model this circuit in the s-plane, to prove that its transfer function is what I have written at the top.

The question I am asking the community is how to approach the first steps for this. I want to use Kirchhoff's current law, but I have forgotten how to express the different voltages and currents.

To be more specific, how can I express i1, i2 and i3 in terms of the voltages, resistances and capacitors? Could you explain your reasoning behind it as well?

I know that i1 is (Vi - Vx) / R1, because I am just taking the potential difference across the resistor, and dividing it by the resistors value, but I am unsure as to what to do next, for i2 and i3.

I know that it will depend on modelling the capacitor in the s-plane as sC, or 1/sC, depending on whether it is in parallel or in series, but again my circuit theory is rusty so when I looked at the solution I couldn't see how they derived it. I can post the solution if it helps.

Thank you


texts: For analog summing and multiplying, what would be the disadvantages of scaling down voltages of input?

texts:
let us say that we have an analog summer based on op-amps. For the reason related to maximum output voltage of op-amps, one wants to scale down the input voltages by constant factor.

Would this cause significant problems for sum? Would there be an internal problem other than noise problems? Would frequencies of an output signal be significantly biased toward some frequency range?


texts: what is the open and closed loop function of this system?

texts:
i found this in the text book.
i solved by:
1- found the closed loop function of just the part of B(p) and its "feedback", let's call it B'(p).
2- after that i did H(p) = A(p) / ( 1 + A(p) * B'(p) )
but in the textbook they solved with H(p) = A(p) * B(P) / ( 1 + A(P) * B'(p) )
so why do you think that is?
this is a screenshot of the textbook solution

the writing is in French, so please ask if you wanna a little explication
PS: sorry i am not familiar with English technical terms since we study in French here.


texts: What limits the maximum number of nodes of a RS422 bus? How to check if N>10 nodes is possible without repeater?

texts:
I have 13 identical devices which communicate with a host via RS422. None of them are addressable (they assume point-to-point connection).

I would like to string them in a RS422 bus. I thought of using relays and Chip Select signals to switch the TX+/- lines of the devices, however I am still facing the "maximum 10 nodes" limitation of the RS422 standard.

I read the limitation to 10 nodes may be extended on a case-by-case basis, but what does this limit depend on and how can I check my 13 devices may comply to the RS422 standard?

I need the full reliability of the standard, so I cannot "just test and see if it works".

P.S: For your information, the devices used are Maxon ENX EASY quadrature encoders with RS422 tranceivers implementing the SSI2 protocol.


texts: Motor freeweeling and regenerative brаking FOR DUMMIES

texts:
The project I'm working on is an electrically powered vehicle. I have found this fairly simple circuit to control my motor's speed.

What I understand is that when the transistor is closed the battery is feeding energy into the motor which moves the vehicle. When the transistor is open the motor is freewheeling and the diode is there to protect the transistor from some kind of voltage that builds up when the motor is rapidly being powered on  and off such as is the case with PWM speed control. Here raises question #1: as the motor is spinning and the transistor is open the magnetic fields of the permanent magnets are still inducing voltage in its coils and thus current, which is energy. Where does that energy go? This question is more of curiosity.

The real question I would like to ask is how I can implement regenerative braking with this setup, which is perfectly explained in this question but I appear to be retarded in some way and I would be really grateful if a simpler explanation can be given.

My understanding is that I would need something similar to this:

Where I will have to first close the upper transistor effectively shorting the motor then when it starts building up voltage I will have to open that and close the lower transistor allowing that voltage to go into the battery and it goes back and forth. The author mentions though that if I'm using PWM then I probably already have regenerative brаking and from what I understand I would need to implement some serious driver logic  which is completely in contrast to what the author is saying. Additionally what happened with the diode, what is protecting the transistors now? I tried adding 2 diodes but I get a short no matter what I tried... Obviously I need some help.

Note: It's a brushed permanent magnet motor.


texts:
We have 4 12-24V motors which we want to connect to a 14,8V battery. Two of the motors are position controlled (M3 and M4, see figure) and will not draw much current as they will mainly be stationary. The two other motors (M1 and M2, see figure) will be moving all the time but with some short spikes in the load (and thus draw more current). Between the motors (M1 and M2) and the battery, we have a Roboclaw 2 x 60A Motorcontroller. This is supposed to tolerate as much as 34V. In the specifications, the motor controller is said to have a Battery Protection feature, whatever that means.

Until now we have only powered the circuit with an AC/DC power source but now we want to use the battery. So the question is: Do we need some kind of battery management system or can we just replace the AC/DC power source and connect it as it is?

Unfortunately, we don't have any specifications on motors M1 and M2, but we have never experienced that they draw more current than 40A when we have applied 14 V to them.

Could, for instance, the situation when the batteries are closed to empty cause damage to the circuit?


texts:
I was looking at the TPS63700 DC-DC inverter datasheet and stumbled across the schematic below. It is a more or less usual buck-boost inverter topology schematic, except for the weird R4 and C3 components. I haven't got much experience in SMPS design, however, I've never seen a feedback loop with these components. The datasheet says that

  To speed up the control loop, a feed-forward capacitor of 10 pF is recommended in the feedback divider, parallel to R3. To avoid coupling noise into the control loop from the feed-forward capacitor, the feed-forward effect can be bandwidth-limited by adding series resistor R4. A value in the range of 100 kΩ
  is suitable. The higher the resistance, the lower the noise coupled into the control loop system.

So, my questions:

What exactly do they mean by "speeding up" the control loop and why or how does it enhance the performance?
Except for the mentioned induced noise in the feedback circuit, are there any other drawbacks of using this schematic?
In which SMPS topologies can this feedback quirk be used (especially in high-order ones like SEPIC, Cuk, etc.)?
Should this feedback quirk be used with other ICs and if not - why?

TPS63700 datasheet link: http://www.ti.com/lit/ds/symlink/tps63700.pdf


texts: Does differential sending benefit current sensing circuits in the same way as differential voltage sending?

texts:
I'd like to send two currents along a long twisted pair (well, ~5m, but I want to be very careful about noise in this experiment). The two currents are produced by two photodiodes with equal and opposite bias voltages, with the same incident light, giving equal and opposite currents. At the receiver end, these currents are sensed by a transimpedance amplifier into an ADC.

Sending voltages differentially gives a benefit to common mode noise rejection. Does the same benefit apply to differential sending of currents? I am unsure as to the mechanism by which "pick-up" from EM interference affects the signal. I'm interested in sensing signals up to around 100kHz.


texts:
I'm toying with the idea to build a music player. Now, before you close this as an exact duplicate: they often do this with a single board computer with a high end controller like ARM9, running Linux.
I do have experience with microcontrollers, but not with (RT)OSes, and I would like to do it without Linux or so.
Audio can be in MP3 format, but also native PCM. (I don't mind the larger files, a 500GB hard disk is a lot cheaper than a 50GB SSD). So I'm thinking of a very basic setup of a Cortex M3 controller (possibly NXP LPC1700) connected to a hard disk and a DAC, a few buttons and a text LCD.

What are possible pitfalls, and is this a good idea from the outset? And I must have overlooked some things too?

Edit:
The hard disk I want to use will be IDE, I don't thin an LPC can handle SATA.


texts: DIY solar setup related questions on following topics: VSR, storing batteries correctly, wiring diagramm, misc

texts:
Please keep in mind I am not an electrician, however I have spent a lot of time researching the basics to obtain a fundamental understanding of the topic. Also, this project is an enhancement to an already in-place basic dual battery setup that my recently purchased campervan came with.
In my drawing (it is the first ever draft, and thus very very terrible, and I am sorry if this is offending somebody !). However, I am glad I did this exercise as it raised a couple of questions. Before I ask them, here is the current setup that I am running: VSR -> Aux Battery 105 Ah AGM. All the appliances are directly attached to the battery. Such as the fridge, some LED lights and USB outlets.

Questions I have:

How do I nicely integrate the VSR in my solar setup? My assumption would be, I can just leave it as is, i.e. connected to the alternator and to my battery directly?
Can I store my batteries safely on top of each other? I have limited place to use, so I am thinking of just piling them up with a frame that holds them in place (running in parallel)?
How would it look like, if I were to integrate a shore-power plug? Would I have to connect it to my inverter and make sure my inverter supports 240v AC input??
Also according to my calculation, 400w should do, but withuot much backup/autonomity. Also, the charging capacity from the alternator is not considered in this calculation. Because, well I dontk now how to incorporate that? Only thing that comes to mind is, I would have to basically measure the charge of the alternator while the engine is running and then extrapolate using some average hours of driving per day etc.?

PS: CB stands for circuit breaker.


texts: Heating up a nichrome wire, MOSFET got too hot

texts:
I'm trying to get a 37 AWG, 0.6mm diameter nichrome wire to reach 300*C so it can heat up inside of an enclosure and according to its datasheet that requires 5A, I cut out enough nichrome wire to offer 2.4ohm. The source provides 12V and 5A max, the MOSFET used is STFH18N60M2(datasheet) and it acts as a switch and I'm sending a PWM signal(%100 duty cycle at the moment) to its gate from Arduino.
Now the nichrome wire does heat up, I don't know if it reaches 300*C but what went wrong is that the MOSFET apparently got too hot and melted the plastic of the breadboard where it was connected, I didn't think I would need a heatsink and I'm wondering if something is wrong with my circuit:


texts:
I'm trying to repair a water damaged PCB. Wondering if anyone has any ideas how to identify these two components.

Thanks!


texts: Is it common practice to combine common mode chokes back-to-back in series to eliminate/reduce RF interference in different frequency bands? As a random  example, placing this in series with this in series to reduce/eliminate RF interference in both AM and FM bands. In the few PS schematics I've come across on the web I've only seen single chokes with low value capacitor networks afterwards to filter RF, haven't seen multiple chokes in series. Any caveats to doing this?


texts: High-Speed PCB Design - Routing on Power Plane Layer?

texts:
I am working on designing my first high-speed PCB with 4 layers (in order):

Top Layer:  Single-ended/TTL signals
Internal Layer 1:  Power Plane (3.3V)
Internal Layer 2:  Ground Plane
Bottom Layer:  LVDS signals

I have some critical connections made on the top layer but due to the layout of the PCB (which is pretty much fixed due to mechanical restrictions) I am unable to fit all of the single-ended signal traces on the top layer. Would there be a downside to moving some of these onto the second layer (containing the power plane), or should I leave the plane unbroken? The internal planes are intended to isolate the single-ended signals from the differential traces, and considering the ground plane (the plane closest to the LVDS traces) is still unbroken I was wondering if this could be done without causing signal integrity issues.


texts:
I was watching a video online (https://youtu.be/YlP2u1mqw7A?t=1380). Minute 23:00.

He mentioned that the time constant for an op-amp is (for a first-order exponential system)

$$\tau  = \frac{1}{2\pi f_{3dB}}$$

I'm a bit confused by that. I haven't seen that before. Usually, I associate time constant with some sort of capacitacne, but this is frequency? I realise it's due to the internal compensation of the op-amp but is there no capacitance?

Or is the capacitance value embedded within the f3db pole frequency?