texts: Creating a Sequenced Array of 3 Mosfets with Adjustable Timings

texts:
I am comfortable with rudimentary 555 circuits and other basics, but I have something a little bit beyond me now.

I need to have three separate mosfets A, B, and C all turn on and off in sequence.  I want to be able to control the timing of on state separately if possible, but it's not absolutely necessary.  I would be fine with all of them having the same ON time so long as I can control the period of the entire cycle so that I can speed up or slow down the frequency.

I'd like to be able to do this in the 10Khz to 1Mhz range.  I've been told there are basic integrated chips that will let me do exactly this sort of thing, but I haven't the foggiest what part number or catalog page to look up.


texts: I am working on a project that uses msp430G2553 as the main microcontroller. I bought an LCD from here https://www.adafruit.com/product/2088 but its libraries are all written for Arduino. Has anyone had the experience of rewriting the Arduino library code to adapt to msp430? Or more generally, how should I modify the libraries to adapt to msp430? Thank you very much!


texts: Top layer ground flood on 4 layer board - how should the ground planes be connected?

texts: I have a 4 layer board, with inner layers being power and ground. After laying out the components and completing the tracking I do a top layer flood as an additional ground plane. How should the two ground planes ideally be connected? [There are ground plane connections through ground vias near the components]


texts: What do TA, TG and M mean on the scheme?

texts:
I have a electrical scheme but I can't get what do TA, TG and M mean?

Can anyone explain me?

P.S. I am a programmer, not an electrical engineer, so maybe it's a trivial question.


texts: This is from N9005 phone and i would love to know what SMD component is this. Here is a photo. Thank]1


texts: Bulk Capacitance and Inrush Current Limiting Diodes burn for PSU first stage

texts:
I've been trying to get the first stage of my power supply working for some time so that I can move on to the more interesting Voltage regulation circuitry for my variable bench power supply.

After making an initial mistake in the circuit, I had new boards made after getting some great help in this forum, which ended with the design below:

The 4 open connections in the schematic above is where the Inrush Current Limiting Board connects into the circuit.

Here is the board layout with the DC ground connection being the middle connector on the right.

Just for completeness I've also added the Inrush Current Limit board Schematic below. The resistance will remain in place for 2 seconds and then get shorted out allowing the full current to be available to the rest of the PSU.

Here is the board layout for the Inrush Current Limiting.

The Problem
When I power on the circuit, the voltage on top right of the connectors of the first board, relative to the middle connector, builds up to around 50V which is what I expected, but doesn't quit stabilise. The Voltage on the bottom connector builds up to -9Volts but keeps dropping. (Not what I expect, this should be sitting at around 20V)

When I energise the relay, D2 and D4 of the regulator burn up quit dramatically.

BOM:
 - All Caps are 470uF 50V (I know this voltage is not really high enough, but I'm planning to swop out the transformer for a lower voltage version before drawing much current from it)
 - Diodes are 5A capable each and will tolerate spikes of 100A.
 - Inrush Current Limit Resistors are 470ohm 3W each.
 - Transformer is toroid with two secondary windings of 18V/80VA and 4.4A each.

My best guess so far is that there is a short somewhere on the low side of the Bulk Capacitance board, but I have not been able to find it at all.


texts: Li-Ion pulse discharge to improve output characteristics

texts:
There are many scientific studies done on pulse charging of Lithium-Ion batteries. However, I have found nearly none on pulse-discharging those.
Here is probably one of the few-ones.

This study employs a well know effect of Lithium-Ion batteries to regenerate the voltage after the load was interrupted, thus dramatically increasing the specific energy (Wh/kg).

"Figure shows a Comparison between Constant Current and
Pulse Discharge at 600 A/m. Constant Current discharge
ends at about 2 s while pulsing results in a total on time of
16 s increasing the discharge capacity by 8 times."

It, obviously, won't give any benefit where the constant load is applied to a single battery, however, by distributing the constant load in pulse form within the battery pack should prolong its capacity as well as its lifetime greatly.

Besides the active control needed, I do not see any extra drawback of this approach.

Why didn't it become de-facto standard within the battery-powered device market?

I would really appreciate any reference documentation on this topic.


texts: What is this RC local feedback configuration?

texts:
I'm studying power converter control loops using Christophe Basso's book
Designing Control Loops for Linear and Switching Power Supplies.

A very common pattern in the compensator circuits is a resistor in series with
a capacitor (\$R_2\$ and \$C_1\$ below, please disregard \$C_2\$) providing local feedback from an op amp's output to it's inverting input:

I'm having trouble understanding specifically how this affects the transfer function (like which R's and which C's produce time constants that add a pole or zero) and
I've yet to find a place where it's actually spelled out. It seems like one of
those things that folks figure is obvious to the reader and never explicitly
describe :)

It doesn't match any op amp amplifier circuits I've seen, although there is an augmenting integrator described on p59 of the TI Handbook of Operational Amplifier Applications2 that is quite similar except that the position of R2 and C1 are reversed. From piecing together odds and ends on some application notes and what not, I understand this adds a pole and a zero to the transfer function. But I'd really like to be able to derive that for myself, perhaps helped along by some examples and more description.

Does this configuration have a name that I could search on to learn more? Or is it perhaps easily explained?


texts: Non invasive sensor for water measurement in pvc?

texts:
Background

I am on a project where they want a non invasive sensor for usage. There are many sensor available but they need to cut down the pipe to place within.

Specifications

Pipe is PVC 1-1/4" OD, meaning 1.38" inside diameter, near 0.14 inch wall thickness.
The water inside is not pure. It contains less than 20% impurities (chemical waste like salts, potash, ammonia).
To cut down pipe mean to insert a water valve type sensor but it is a fixed solution. Our project needs a portable device
I am not interested in actual amount in cubic meters, I just want how much it is filled.
As for as temperature sensor is concerned the temperature change is a big factor because otherwise we would need to calibrate it according to ambient temperature.
The pipes are placed horizontal and water is pumped by 5 horsepower motor.

The Ask

Can any one can tell me how can I make a sensor that can check level of water inside pipe like 75% filled. We need to detect if water approach a specified threshold . I tried magnetic coils but they are not working under varying temperature and dust. My circuit take 12 volt dc.


texts: How can I override a capacitive touch on-off switch?

texts:
I bought a floor lamp for use with a mechanical timer that turns electricity on and off using a set schedule (for example, when you're away but want to convince others that you're still at home).

Unfortunately, this kind of lamp (I bought it at Target) won't work with a timer because when the timer removes power and then later restores it (normally, this turns a lamp on), the lamp stays off until someone touches it with a finger.

The sensor is on the side of the vertical column of the lamp and I can't mechanically access the sensor itself.

Can anyone think of a way to modify the lamp so as to ignore the sensor and light up when power is restored? Thanks!


texts:
Is there a comparatorlike IC device which compares input frequency with a threshold frequency? I want to make a circuit which monitors input pulse train and whenever it is more than a set frequency the LED will be ON.

I dont want to use a microcontroller.
And 5% accuracy is fine.


texts: Can series capacitors (DC block) be used to clean up LVDS signals over long distance

texts:
I have a system driving LVDS over ~ 140 ft of CAT6 cable.  I am using the SN65LVDS series devices from TI to accomplish this.  I'm aware that there will be low-frequency distortion in the signal at the receiving end due to the attenuation of the cable itself.

I realize there are good ways to equalize the LVDS signals at the receiving end, but I am after a really simple solution.  Can I put caps in series with the LVDS high/low lines to EQ the signal a bit passively?  How would I size them, a decade below signaling frequency?  If there is a 100 Ohm termination resistor between the two lines (H/L), do I use 100 Ohms as the R in the RC calc?

I found this app note that describes what I am talking about a bit, but it doesn't quite answer my question.


texts: 8051 micro controller on chip ROM address range? MEMORY SIZE

texts:
what is the size for each of these chip ?
I know that when we add 1 bit to the memory we double the size.
my question is what is the size for a chip range from (0FFF - 0000) so that i keep doubling when ever I add a bit !


texts:
I have build a circuit that functions as a variable load. It consists of 4 resistors in parallel - let's call them R1,R2,R3,R4 - each with an activation switch (implemeted with a transistor). R1 has the lowest value, the other resistors have value: Rn = R1*2n-1.
I'm currently trying to find an algorithm that calculates the nearest resistance that is above a desired value, Rdes. Does anybody have an idea of how this could be implemented, without looping through all the possible values?


texts: Is this a capacitor start motor and can I start it with a microwave capacitor

texts: I salvaged an old motor out of a air conditioner and I want to know if it's a capacitor start motor if I can start it with the capacitor I have and how to start it.  I included pictures of the motor and capacitor btw i have never worked with capacitive start motors so i need details on exactly how to wire it up with out ruining it


texts:
I want to add this input signal in my hspice code. Here I am doing transient analysis.
How can I do it?


texts:
Considering the following example in paragraph 3.6.3 (Example of angular rate data for FS=250) of STM's AN4505:

Angular rate values | Register address
                    | 28h | 29h
...
100 dps             | A4h | 2Ch

Does anybody can point me out how it comes that 0xA4 | (0x2C << 8) converts to 100 dps? I have already read both AN4505 and part's datasheet, but to my surprise, I couldn't find even a word about how exactly should we understand output register values.


texts: Programming dsPIC30F4011/13 on board dsPICDEM 2 with MPLAB ICD 2

texts:
I have Microchip's dsPICDEM 2 Development Board with two MCUs on it, a dsPIC30F4011 Motor Control MCU and a dsPIC30F4013 General Purpose MCU. I need to program both microcontrollers with the MPLAB ICD 2 In-Circuit Debugger.

When I build a test project (with a program that just toggles on and off LEDs D3 and D4), everything is built successfully (using the C30 Language Tools). The program looks like this:

#include <p30fxxxx.h>

#include "delay.h"

int main(void)
{
    // setup
    LATBbits.LATB0 = 0;
    TRISBbits.TRISB0 = 0;

    while (1)
    {
        LATBbits.LATB0 = ~LATBbits.LATB0;
        Delay5ms(100);
    }

    return 0;
}

(the functions prtotyped in delay.h are functions defined in assembly code in delay.s and have been excerpted from Microchip's examples)

When I program any MCU by means of MPLAB 8.80 and the ICD, I get the message Programming succeeded. However, when I run the program on the board, nothing happends (no LED switches on and off).

I have tried including some files into the project:

libpic30-coff.a under Library Files
p30F4011.gld under Linker Script
p30F4011.h and p30Fxxxx.h under Header Files

but that has not helped.

I have not been able to find any detailed, step-by-step information on how to program these PICs using the named tools, neither in Microchip's documentation nor on the internet.

What do I have to don in MPLAB IDE 8.80 in order to program both dsPIC30F4011 and dsPIC30F4013 with MPLAB ICD 2, assuming MPLAB IDE and ICD 2 are already set up?

Thank you in advance.

EDIT:

I was using the following directives to set the configuration bits:

_FOSC(CSW_FSCM_OFF & XT_PLL8);  //Run this project using an external crystal
                                //routed via the PLL in 8x multiplier mode
                                //For the 7.3728 MHz crystal we will derive a
                                //throughput of 7.3728e+6*8/4 = 14.74 MIPS(Fcy)
                                //,~67nanoseconds instruction cycle time(Tcy).
_FWDT(WDT_OFF);                 //Turn off the Watch-Dog Timer.
_FBORPOR(MCLR_EN & PWRT_OFF);   //Enable MCLR reset pin and turn off the
                                //power-up timers.
_FGS(CODE_PROT_OFF);            //Disable Code Protection

I saw this code in Microchip's examples.

However, this was not working. Anyway, the solution is as Brett pointed out. I tried it, and it worked from the very first time.

I have tried again the first code, and now it does work. Weird. I still do not know what I was doing wrong.

In addition, I have tried removing the files I included, and I have realized that there is no need to include those libraries / header files / linker scripts into the project.


texts: understanding the changing reflection coefficient in TDR

texts:
in the simulation example bellow out Vs=2V rho is the definition of reflection coefficient.
gamma_g=(50-30)/(50+30)=0.25
gamma_L=(10000-30)/(10000+30)=0.25
but in plot of rho they start with -0.25  (not 0.25) then it rises to 1.6 where as in my calculations if we look at the point V_TDR
we start 2*0.25=0.5 then 0.5 is multiplied by 1 at the load and return o the V_TDR  as 0.5+1.
But as you see in the simulation its acting a lot different both the VTDR plot and the rho plot are totaly different.
Where did i go wrong?
Thanks.


texts: Microcontroller IO pin configuration I2C

texts:
I'm using this Microcontroller S32K142 64 pin.
In the reference manual, I can see a lot of pins which I assume to be Output only are mentioned as Input / Output. For example, the Microcontroller is the master I2C Clock. So, in that case, the clock can only be output, right? But why is it given as I/O?


texts: MP3 Player: Disconnect 3-watt speaker from amplifier when headphones are plugged in using MOSFETS and the isolated switch on an SMD 3.5mm stereo jack

texts:
Can I use Mosfets to disconnect a 3-Watt speaker from an amplifier circuit without any loss of sound quality?

I'm using a microcontroller controlled MP3 player called a Flyron FN-M16P, which features both terminals for powering headphones (terminals 4& 5, with GND terminal = 7), as well as an amplifier circuit for driving a 3-watt speaker (SPK+ = terminal 6, SPK- = terminal 8).

I want to have my device play MP3 files to the speakers under normal circumstances, but disconnect the speakers and play to the headphones when headphones are plugged in.
Please see the diagram here enter link description here

I cannot ground SPK+ and SPK-, the manufacturer tells me that this would blow the amplifier.

My initial idea was to use an SMD 3.5mm stereo jack with isolated NC (normally connected) switch, to disconnect SPK+ (Please see my attached diagram), but I cannot find an SMD 3.5mm stereo jack with isolated NC (normally closed isolated switch).  I want to avoid PCB parts.  I have found an SMD 3.5mm audio jack with an isolated NO (normally open) switch from Technik.HK.  Please see the link here enter link description here

Can I use a mosfet based circuit to disconnect the 3-watt speakers from the amplifier pins when this switch gets closed without having it introduce any loss in audio quality?  How would I do that (I'm a mechanical engineer not an electrical engineer).


texts: How to separate ground pour from ground traces in Eagle?

texts:
I'm designing a board where I have ground pour at the component side. I'm using plenty of decoupling capacitors. The problem is that the ground pour "consumes" the ground traces like this:

Is it Ok to leave it like this, or should I avoid it. And if I should, how can I done it in Eagle?


texts: How to definite the total life cycle of battery under a depth-of-discharge(DoD)?

texts:
As we know that battery discharged with different DoD have different life cycle, which is usually described as lower DoD with more life cycle. And I found that there is a euqation to estimate the life cycle of battery shown as\
total life cycle = a*DoD^b
where a and b are special coefficient for different types of batteries.
I think the life cycle here means the charging/discharing times (not the times of fully-charge/discharge). Please just regard the life cycle as charge/discharge time here.
But the problem is, how do we definite the life cycle. To which condition we can think the battery is retired.
I mean that, if we say a battery can cycle 2000 times with a 50% DoD, does it means that the state-of-health (SoH) of this battery will decrease under 50% after 2000 cycle times? or it means that the SoH decrease to zero? or a special value setting as the 'retired level' by the manufactor?


texts:
I want to make a tesla coil with about 3 1/2 or 4 inch secondary coils diameter
With height about 1 meter.I am using 2.5 milimeters copper wire for the primary.Is that primary wire is too small??I can't find any bigger wire on my city.I see other people using a bigger wire for their tesla.And can my tesla coil working properly if i just using the 2.5 mm wire??Thank you & sorry for poor english


texts: Battery Power Source for Wireless Router & Modem?

texts:
I only have access to electrical power via a generator for now, and need to continue to power the wireless router & cable modem even when the generator is out for a good part of the day or night.

Since the cable signal is still there, it only needs the modem & router on so that I can use the laptop on battery to work without the generator. I hope to be able to make a battery source for this setup to run for about 8 hours before recharging is needed.

The wireless router adapter is 19v 1.75a, and the cable modem is 12v 2.5a. The difference in voltage on these seem challenging. I wonder if I can just wire directly to these units from the correct batteries (what types?) because they're DC. Maybe even use a small solar panel to keep the batteries recharged and don't have to resort to the generator for most days.

Since I'm clueless on these matters, please help design this setup and explain what I'd need to do/buy to make it work. Safety is certainly a concern. I can put the battery outside if needed & wire it in, but it needs to be fire safe. Thank you!


texts: What is the purpose of a resistor network?

texts: I ran across a resistor network component, but I can't find any basic electronics tutorials that use these in practice.  What is something like this used for?


texts: Electronic device operating temperature declaration

texts:
How is device operating temperature range determined? I supposed that for a specified temperature range all the built in components have to support it. I am in doubt because I saw some commercial product with specified the lowest temperature of -30°C, but implements some IC  that has 0 - 70°C operating temperature range (see EDIT). And that is crucial part of the device. How is that possible? Is that certification violation? Is it reliable to use in range that is not covered by all the components?

EDIT: I must add that maybe I made bad assumption. Sometimes, device manufacturers have option to order specific IC variants from the IC manufacturers (like variants with industrial, mil/space grades), that are not initially available. In my particular case, the IC I am mentioned is LM380N that has specified operating temperature range 0 - 70°C in the corresponding datasheet. This IC (audio power amplifier) I found in service manual schematic (not by inspecting hardware) for the device I am referring. However, not sure if some other than commercial variant is available and implemented in the hardware. Anyway, I appreciate each answer.


texts: How to identify the transistors that are active loads

texts: I have found this exercise online, I'm currently learning about current mirrors and I don't really get this concept of a transistor acting as a load. Can someone explain? Which transistor is an active load for which transistor?


texts: Piezo speaker equivalent for circuit simulator

texts:
I am using Falstad's circuit simulator to test a design of an Op-Amp based microphone-speaker system...kind of like a megaphone, but the speaker is going to be a piezo plate.  Falstad does not have a speaker or piezo speaker component I can add.  What resistor/capacitor/diode/inductor/etc. would properly simulate a piezo in the circuit?

Current circuit diagram for reference.  The top right box is bandpass filter.


texts:
I have done a previous project where I used an Arduino Mega to control a Three-phase industrial metal pattern scrolling machine (bender), and I faced many problems with noise voltage spikes being read as interrupts on Arduino pins.

I am now doing another project of similar requirements but I am looking into using Cat5e twisted pair for signal transfer:

(Mega-> Opto-isolated Relay Board)
(Limit switches board->Mega)
(Mega<->Keypad)

I am also planning on keeping the signal wires as far off from power wires and boards as possible.

Of course, differential mode is not feasible in this case, but I was thinking of connecting all the white pairs to GND in an attempt to reduce noise and cross-talk.

Has anyone tried anything similar?

The machine is not well grounded, so I do not know if a shielded cable will give me better results or not.
I am still doing my research before I start buying cables and terminals and it becomes more expensive to fix problems.

Any plausible suggestions are welcome.


texts: How do I create Flow Chart using Visual Designer in Proteus and take a reading off grove ultrasonic sensor?

texts:
I have this my  schematic

This is the Visual design


texts:
I am trying to communicate an arduino with a Silabs F560 Toolstick Daughter Card.

On Arduino (Master)

I have loaded the i2c scanner program from http://playground.arduino.cc/Main/I2cScanner
which basically pings all possible address (0x00 to 0x7F) on the bus trying to get an ACK.

On C8051F560 (Slave)

I have loaded the example Slave code given by Silicon Labs of address 0x78.
I have changed the SMBus frequency to 100000 (since Arduino works on 100kHz)

The Arduino was not able to recognise it on the bus. I have tried pull-up resistors of different combinations 3.3k, 6.6k, 10k ohms. That didn't make any difference.

When I tried to analyse the bus with a logic analyser, the SiLabs MCU was disrupting the SCL driven by Arduino.

I think an example code given by a manufacturer should work fine.

Is there anything I am missing ? or is it the H/W that is damaged ?


texts:
I have designed my own PCB and it doesn't work correctly.
I needed to have a PCB that has only one push button to switch on and off a laser diode. The circuit does work kind of, but the laser diode only shines a little, it doesn't give the amount of light it supposed to.
Can somebody help me with solve this problem?
I have added the schematic and PCB design as images.
I used a 555 timer to design this PCB and I have already added a 220 ohm resistor to ground and pin 3 of the laser diode.


texts: Can I draw power for a component while this charger is charging the battery?

texts:
So I am working on a design for battery-heated wrist warmers. My mother has Reynauld's and arthritis, and as winter approaches it gets much worse.

My basic design is that I will take a form-fitting sleeve (made from a shirt or tube sock), weave nichrome wire through the sleeve, wrap thinsulate or space blanket around that, and then fix a nice-looking knitted wrist warmer over it. At the very least I think it would be a good start even without electric heating.

For the electric heating, I am thinking of using a 1000mA LiPo battery, a button switch, and a USB charger.

Ideally, the charger will charge the battery while also providing heat. My specific question is: can the charger I linked to provide that? In a more general sense, I would appreciate any suggestions you might have!

Thanks, and happy holidays!


texts: NMOS High frequency, fast bi-directional switching, 12V 100A

texts:
Context

I want to charge a battery bank from a car alternator. Either side may have a higher voltage than the other, e.g.:

Battery bank can be 14V while alternator-side is 12V (engine off, solar charging)
Battery bank can be 12V while alternator-side is 14V. (engine on, solar not charging)

I thought of using a relay, but the battery may be able to draw a higher current than the alternator can support. Therefore, switching to control the current is essential.

The current is very high, e.g. 100A, and therefore fast switching is needed to reduce heat build-up. By using MOSFETs in parallel, the current and consequent heat is reduced significantly.

To reduce jolting action on the alternator when switching on, and therefore reduce stress and increase lifetime, I imagine the switching ought to be high-frequency. Maybe 1000Hz is sufficient?

I'm interested in using NPN, because they're much cheaper. I'll use a cheap DC-DC boost circuit to provide 25V for driving the gate.

Schematic

simulate this circuit – Schematic created using CircuitLab

Problem

1) Should the body diodes face towards eachother or away from eachother?

2) In the diagram, the connection is:
Battery -> Vd -> Vs + Vs <- Vd <- Alternator

Will Vs be floating when both MOSFETs are off? E.g. is it possible that Vs becomes 0V and therefore violates the Vgs max rating?

I was thinking that by facing the body diodes towards eachother, Vs will never be less than the highest voltage minus the drop over the body diode.

Also, I'm wondering if current has to be able to flow from Vs? Again, in the current schematic, with body diodes against eachother, I don't see how Vs would allow any current to flow.

3) I'm in particular worried about violating the Vgs< +-20V rating.

When Signal=5V then Vg=25V, max Vs=14V, max Vgs +14V.
When Signal=0V then Vg=0, Vs=(0-14V?), max Vgs -14V.

Is this correct?


texts: ATmega168 crystal resonator more than 20 MHz

texts:
I try to make an SD card-based WAV player with ATmega168. I have connected a 16 MHz quartz crystal, and it can give a 64 kHz carrier frequency and a 8 kHz sampling frequency.

But in that project I can multiply my frequency. So I connect a 16 MHz quartz crystal to ATtiny85, multiply it to 64 MHz and give a 250 kHz carrier frequency and a 32 kHz sampling frequency - much better.

I can't find a multiply function in the ATmega168 datasheet, so can I just connect a 64 MHz quartz crystal to MK?


texts: Does these terms consider the same Voltage, electric potential, and potential difference

texts: What are the differences between these terms ? do they are considered the same


texts: Load resistance determination in Zener Diode

texts:
Design a Zener regulator, regulated power supply using a 12V zener diode. When source voltage range from 15V to 20V and the load current ranges from 20mA to 100mA.

a. Determine proper choice of Ri

b. Determine maximum power dissipated in the Ri

c. Determine the output voltage Vout min and Vout max if Zener Diode has a resistance Rz = 3 ohms

Here is the circuit diagram :

simulate this circuit – Schematic created using CircuitLab

My question is how do I determine RL?
As far as I can tell the information about range of input voltage and range of load current will help me calculate RL. But how to do it?
Also, the min and max limit of current through load is given, for what value of Vi will load current maximum and for what value of Vi will the load current be minimum?


texts: TPA3220: Single supply operation - can I use AVDD to pull up RESET?

texts:
I've tried asking this question on the TI forums but have not been able to get a response, so I'm posting here in the hope that someone who knows the details of the TPA3220 will be able to answer!

I am designing a product that uses the TPA3220 power amplifier in single supply mode (powered by a TPS55340 30V boost converter).

When in single supply mode, 5V is made available on the AVDD pin via an internal LDO (which is powered by the 30V single supply).

The amp is turned on by pulling the RESET pin to 5V. I'm wondering if RESET can be connected to the AVDD pin to turn on the amplifier?

On page 25 of the datasheet it says that "When RESET is released to turn on TPA3220, FAULT signal will turn low and AVDD voltage regulator will be enabled". This suggests that AVDD will not be available until RESET is already high, i.e connecting them would not work because it would create a circular dependency.

If this is the case, how should I turn on the amplifier if I am running it in single supply mode without an external 5V supply?


texts: 40% Channel Utilization on 1Mb Satellite

texts:
Using the Slide Window technique, consider a satellite channel with:

500 byte frames sends
270 ms delay on send and receive
1 Mbps rate
communication protocol is Sliding-windows
Ignore the length of ACK messages.

How many bits are needed for numbering the Frames to achieve 40% Chanel utilization?
My professor calculated it to be 5 bits.
But I think 6 bits is correct.
Can anyone could help me which of these answer is true?
EDIT: he used : U = w / (1+2a) formula.
First Answer:
1/(1+2a) = 1 / 136   --->  W/136 >= 4/10 ---> W>= 54/4  ----> 6 bit.
Second Answer (the way one person solved it):

I search on the net and found something similar:
http://staffhome.ecm.uwa.edu.au/~00014742/teach/ind426/handouts/tutorials/solutions/tute3.pdf
in problem 1-b. but i couldn't infer any new things for my problem.


texts:
The task is to find the operating point of this transistor:  Given information:

\$E_{C}=12V\$, \$V_{BE}=0.6V\$, \$V_{IN}=5V\$, \$\beta=200\$,    \$R_{B}=440k\Omega\$, \$R_{C}=5k\Omega\$, \$R_{E}=3.3k\Omega\$

  The answer to this excercise is \$I_{C}=0.8mA\$ and \$V_{CE}=5.36V\$.
My problem is that I cannot get the right \$I_{C}\$. I start with calculating \$I_{B}\$ which is: $$ I_{B}=\frac{V_{R_{B}}}{R_{B}}=\frac{V_{IN}-V_{BE}}{R_{B}}=\frac{5-0.6}{440000}[A]=0.01mA $$
Then, using the formula \$I_{C}=\beta\times I_{B}\$   I get \$2mA\$ which is clearly wrong.

If I use the \$I_{C}\$ straight from the answer, I can finish this exercise, using this equation: $$V_{CE}=E_{C}-I_{C}R_{C}-I_{C}R_{E}=$$$$=12-0.8\times10^{-3}\times5\times10^{3}-0.8\times10^{-3}\times3.3\times10^{3}=$$$$=5.36[V]$$

So the question is: "How to calculate the base- and the collector current?".


texts: IS this the correct way to control the speed of a 4 wire CPU fan?

texts:
The circuit is used outside of a PC.

simulate this circuit – Schematic created using CircuitLab
The fan hums (but still spins) on the MED and LO settings. Does this mean the circuit is the wrong way to control the fan? If this circuit is the wrong way to control the fan, please edit the schematic to make it right.


texts: A few basic questions about simple electric circuits

texts:
For beginning, sorry for my english and for long post. But maybe it would be useful for others newbies. I'm trying to understand basic things about electric circuits on my own, and at the moment I become confused, so have to ask for help.

First I would like to describe how I understand processes in DC circuit, and then ask question about AC which cause confusion.

So, we have simple circuit consisting of battery, switch, couple of wires and resistor.

When switch is closed, transient phase begins, current start to flow in both wires simultaneously:

At first I thought the current is "usual" current that we are measure with amperemeter, but then realize this is "charging" current instead. Because to "create" potential at some place we need to move charge at the place (i.e. we need a current). And amount of charge needed to create certain voltage depends on capacitance. So this small current is not "main" current, and required only to create surface charges on wires i.e. voltage.

Eventually, in a few nanoseconds, maybe after some reflections, steady state is established. No more charging current. Now, these surface charges create electric field not only between wires but also inside the wires and the resistor. And this inner electric field cause electrons to move, thus we got "main" current, which obeys the Ohm law:

The image from Matter and Interactions by Ruth W. Chabay, Bruce A. Sherwood.

Or you can read about surface charges in article by J. D. Jackson "Surface charges on circuit wires and resistors play three roles"

Now if battery is replaced with AC voltage source I become confused. Hence there are, roughly speaking, 2 kinds of currents - charging / discharging and "main" current.

Unfortunately, I can't find anywhere such detailed description for AC, so I have a few questions.

Question 1:

First, is my description of DC is correct ? Because if my understanding is wrong, there is no point to move further.

Question 2:

Now, if I imagine AC as follows:

In open circuit there is only constant charging / discharging currents and "main" is absent.

If some load is connected then there would be constant charging / discharging currents AND, along with it, "main" current. I.e. constant surface charges redistribution due charging currents would create constantly increasing, decreasing and flipping electric field inside wires and resistor. Again, as result, we got "main" current due this inner electric field. But since the field is constantly changing now, electrons just slosh back and forth.

I'm assume this is oversimplified view since in this case changes in "main" current will always happen after charge redistribution in the circuit.

Anyway, is this wrong or acceptable description ?

Or it would be appropriate only for low frequencies (because if frequency really high and wire potential is differs along it, I cant even imagine the picture, total mess).

Question 3:

In general, are these constant charging / discharging currents ignored for simplicity in circuit theory, despite the fact, the are always actually present ?

I mean if I measure current in AC circuit or look at graph for example of AC RC circuit where current curve lead voltage by 90 degrees, it always related to "main" current, and not these charging / discharging currents ?

Question 4:

Are these these charging / discharging currents flow on surface of conductors (since they create surface charge) ?

Thanks for any help.


texts: High side or low side LED driver with NPN BJT? Which is better?

texts: I think the B configuration would be more stable in temperature variations, anyhow I would like to hear some good suggestions on which configuration should be used and what will be the benefits of using the one compare to the other.


texts: How is the phase of the applied voltage related to the phase of the induced emf in an inductor?

texts:
As I understand it the induced emf in an inductor is generated directly in opposition to the applied voltage, so would that mean that it is 180∘ out of phase with it?

Also, what then is the phase relationship between the source voltage and the current through the circuit?

In both cases I am simply talking about an inductor connected to an ac voltage source.

If anyone could draw a diagram that would be great. There are plenty on the relationship between the current and phase across the inductor but none on the relationship between the source voltage and the above parameters.


texts: Isolation for USB 2.0 High Speed (480 Mbps)

texts:
The fastest isolators available a a reasonable cost are 150 Mbps per channel. High Speed USB has a data rate of 480 Mbps. So how do you isolate a HS USB?

The first thing that comes to mind is to somehow convert the serial stream into n parallel streams which run at about 480/n Mbps each and then send these parallel streams over the available isolators and convert it back to serial on other side. I'm sure this is not as easy as it sounds.

I have seen some expensive looking FPGA based designs that do this. Since it can be done using an FPGA, I wonder why no semiconductor company is providing a ready to use 480 Mbps USB isolator. This approach looks so scalable that even higher rates could be possible.


texts: i know the effects of soldering photo-resistor to HC-SR501 PIR module. It then detects movement in the dark only. But can anyone tell me that what is the effect of adding a thermistor to the same PIR module? There is a provision in module itself to solder both photoresistor and thermistor. I searched on the internet but in vain. I m sure someone here can help me out. Thanks in advance.


texts: Is it possible in circuit design to split like say a temperature sensor line reading into 2 wires, and read by 2 different system/circuitry? My motive is to tap the signal line in a safe way without affecting or disrupting the other system functioning.


texts:
I need to make a speaker that is capable of creating several tones for a school project, so nothing too big nor expensive.

I'm using a micro controller sending a frequency to a transistor and the transistor is connected to 12v and the speaker.

The sound level must be a minimum of 80 dba in a 2 meter radius. I could only achieve 70 dba with a 3W 8 ohm speaker salvaged from an old radio.

How can I make it louder? Should I change the type of speaker?


texts: How to connect two load cells to one HX711?

texts:
I have two 5 kg load cells and one HX711. The project's goal is to connect them together, and measure the weight of the same object. I would like to get the average in order to make my calculations more accurate. I hypothesized that this is how the connections would go. I have labeled them in order to make it clear. These are the datasheets:
Load cell
HX711
Each one of them uses a full-bridge configuration.


texts: What is the formula to convert the result of an 8-bit ADC to voltage?

texts:
I'm just struggling with one of the questions in my Computer Hardware assignment.

An 8-bit A-D conversion chip is configured to sense a voltage in the range 0 to 6V. Given an analog input voltage of 2.5V, determine, showing full working, what the 8-bit digital output should be.

So, using formula given by professor solution is:

2^8 = 256 so (2.5/6)/255 ≈ 0.002V

But, when I did some extra research, I found a different formula:

(2.5/6) * 255 = 106.25

So, which formula is correct and why?


texts:
I am replacing a toaster oven heating element and found this loose connection & burn on the circuit board. Does this look like I could successfully solder it back in place?

Thanks.


texts:
I'm working on a radio module that is made to transmit from a rocket to a ground station for a homemade project. The airframe is made of carbon, therefore I cannot place the antenna(s) inside the rocket (carbon is not RF transparent). However, placing the antenna on the outside of the rocket proves to be an issue as the carbon attenuates the RF, and quite a bit of power is lossed.

Are there any dielectric materials that I can build from household items to insulate the antenna from the carbon? I've tried teflon, mica, and aluminum foil, which seem to work well, but are not quite up to my standard.

Thanks in advance

EDIT:

SECOND EDIT:

After testing S parameters, the most intriguing result was that of S11. The VNA documented a reflected power of -12dB when using mica as an insulator 10mm off of the airframe. This 10mm of separation was done with foam that we had lying around. Using the solely foam to separate the antenna from the carbon resulted in a reflected power of -7dB at 10mm and -4.3dB at 7mm. The mica sheet alone gave a reflected power of -3.4dB. These numbers are all on top of the -0.3dB that is reflected when the patch is placed directly onto the airframe, which is a significant distance.


texts: Ethernet magnetics - PHY side center tap isolation

texts:
I am designing a PCB that will use a Microchip KSZ9896C 6-port Gigabit Ethernet Switch. In the datasheet (section 7.2) they state that :

"the four transformer center tap pins on the KSZ9896C chip side should not be connected to any power supply source on the board; rather, the center tap pins should be separated from one another and connected through separate 0.1μF common-mode capacitors to ground. Separation is required because the common-mode voltage could be different between the differential pairs, depending on the connected speed mode."

I want to connect the switch to a 2x2 Gigabit modular jack. The confusion I am having is that most, if not all, ganged modular jacks have the transformer center tap pins from the common mode filter connected together and sent out one pin (for each individual port). Even if the pin is left unconnected, all of the center taps are tied together in the jack and, therefore, not isolated. Correct?

I am totally new to Ethernet magnetics so I am trying to figure out if a 2x2 ganged jack will work. Any help?

KSZ9896C : http://ww1.microchip.com/downloads/en/DeviceDoc/00002390A.pdf

BelFuse 2x2 Gigabit MagJack : https://belfuse.com/resources/drawings/magneticsolutions/dr-mag-0879-2c2r-54.pdf


texts: Why the conversion time of an ADC is calculated as: number of bits in resolution+number of programmed sample clocks+2/(ADC clock frequency) ?  As far as I know for the successive approximation A/D converter, a clock cycle is the time it takes for a bit so number of bits in resolution would give us n cycles, so why this number is added to 2 and the whole thing is divided to the clock frequency? The microcontroller is HCS 12 and uses successive approximation A/D converter


texts:
Disclaimer: I am very new to electrical engineering, but I'm determined to figure this project out.

I'm currently working on electronic solenoid lock. Here's a image of what I have so far.

I have a Raspberry Pi Zero and I'm attempting to use PWM to switch between 0V, 6V or 12V. The lock remains open at 6v, it pops open at 12v and stays locked with no power.

I've read up on Duty Cycle and Frequency and I know how to set that in Python, but I can't figure out what duty cycle % and frequency I need for each of the three states.

For example I'm setting the duty cycle at 100 and frequency at 50 to simulate 12V by doing this:

p = GPIO.PWM(12, 50)
p.start(100)

And then basically doing the same thing for when I want to simulate 6V:

p = GPIO.PWM(12, 50)
p.start(50)

Is this the correct way to do this? Also how would I simulate 0V?
Any other advice is welcome, I have no idea what I'm doing :P
Thanks!


texts:
I'm trying to make a PVA using the following schematic:

I have put something together that looks like:

Obviously the input at the top will have positive lead going into the diode and the negative lead on the other side.

Is this correct, I have little knowledge and not really sure about schematics. I want to use this to test my ignition system.

If it's wrong could someone point out what needs to be changed or draw a simplified version (I understand the schematic may be as simple as it gets) or alter the image of my PVA so it's usable?


texts: STM32F7 Bootloader unable to jump to application

texts:
My problem is that my bootloader is not jumping to the application, or maybe it is but then jumps back to the bootloader because of an interrupt. To give you something to work with here are some info:

The code that jumps to the application

typedef void (*pFunction)(void);

pFunction Jump_To_Firmware;

void JumpToInternalFlashImage()
{
    Jump_To_Firmware = (pFunction) (*(uint32_t *)(0x08008000 + 4));

    __set_MSP(*(uint32_t*) 0x08008000);

    Jump_To_Firmware();

}

How main looks in the application

int main(void)
{
    // Copy ISRs to RAM
    memcpy((uint8_t *)&_isr_vector_ram_start, (uint8_t *)&_isr_vector_flash_start, &_isr_vector_flash_end - &_isr_vector_flash_start);

    // Relocate the vector table
    SCB->VTOR = (uint32_t) &_isr_vector_ram_start;

    HAL_Init();

    SystemClock_Config();

    MX_GPIO_Init();
    MX_DMA_Init();
    MX_USART2_UART_Init();

    while (1)
    {
        HAL_UART_Transmit_DMA(&huart2, "hello", 5);

        uint32_t i =0;
        for(;i<1000000;i++);
}

It should perhaps be pointed out that this program works fine if I program it through ST link without any bootloader code. Also the important parts of this code should be the first lines where I copy the ISRs to RAM and then relocate the vector

The linkerscript looks like the following to give you an idea of where the addresses come from ( it looks the same in both bootloader and application )

/* Entry Point */
ENTRY(Reset_Handler)

/* Highest address of the user mode stack */
_estack = 0x20050000;    /* end of SRAM2 */

/* Generate a link error if heap and stack don't fit into RAM */
_Min_Heap_Size = 0;      /* required amount of heap  */
_Min_Stack_Size = 0x400; /* required amount of stack */

// There are more areas but these should be the only relevant ones
MEMORY
{
   FLASH (rx)      : ORIGIN = 0x08000000, LENGTH = 1024K
   RAM_ISR (xrw)   : ORIGIN = 0x20000000, LENGTH = 512
   RAM (xrw)   : ORIGIN = 0x20000200, LENGTH = 64K - 512
}

SECTIONS
{
    /* The startup code goes first into FLASH */
    .isr_vector :
    {
        . = ALIGN(4);
        _isr_vector_flash_start = .;
        KEEP(*(.isr_vector)) /* Startup code */
        _isr_vector_flash_end = .;
        . = ALIGN(4);
    } >FLASH

   ._isr_vector_ram (NOLOAD) :
   {
       . = ALIGN(4);
       _isr_vector_ram_start = .;
       KEEP(*(._isr_vector_ram)) /* Startup code */
       . = ALIGN(4);
   }>RAM_ISR
}

So my problem is that when I try to jump to the application it doesn't work

The first addresses from 0x8008000 ( application start address ) looks like

And at the address 0x08004DD1 it looks like

What happens is that I always end up stuck when the program counter points at(it does not move from this address when trying to step further )

0x8007770

and MSP

0x2004ffe0

in the output.map for the bootloader I can see that 0x08007770 is

.text.Default_Handler
            0x08007770        0x2 startup/startup_stm32f746xx.o
            0x08007770                RTC_Alarm_IRQHandler
            0x08007770                EXTI2_IRQHandler
            0x08007770                TIM8_CC_IRQHandler
            0x08007770                DebugMon_Handler
            0x08007770                UART8_IRQHandler
            0x08007770                SPI4_IRQHandler
            0x08007770                TIM1_CC_IRQHandler
            0x08007770                DMA2_Stream5_IRQHandler
            0x08007770                HardFault_Handler
 and so on (the rest of the handlers )

Does anyone know what my problem is and how to solve it ? Please feel free to ask questions if you feel like I've missed to tell you something


texts: Building a Battery Charger with an LM317

texts: I was told that i could make a simple battery charger from a LM317 and a resistor to charge some Ni-MH Batteries. Can someone just expand on this a little such as how it works as I don't really understand it. Some more information is that there are 12 AAA batteries that hold a charge of 1000mAh and 1.2v per cell.


texts: The best way to judge the capacitive and inductive load

texts: I've a ADC sampling system. What I can get from the connected load is the sampled data of the output voltage and output current. I want to know if the load is capacitve or inductive from these datas. For a pure AC wave, I can get the information from the time of the 'zero crossover' point. But in my situation the AC may contain high frequency harmonics. Does the 'zero crossover' method still work? Is there other (faster) method to do this work?


texts: RF receiver design - estimate received power

texts:
I'm designing a radar receiver, whose block diagram is below:

When I compute power received from radar range equation, it varies between -90 dBm to -40 dBm depending on the object's location (60 to 6 meter).

After I downconvert frequency to 1-10 kHz range, the signal is still too weak so I'll need to amplify it once more so here's my question:

How much do I need to amplify the signal so that the input at ADC (say, 16-bit, Vref=1V) is 1 Vpp, not clipping and not too low so it's always properly detected?

I've used ADIsimRF and it looks like if I assume that I receive -90 dBm, I need to amplify the signal by 70 dB to get 200 mVpp, which means that if I receive -40 dBm, it will give me 54 Vpp.

Is there a way to anticipate how much power will I really be getting (say, 6 dBi patch antennas, radiated power is 12 dBm) or is there a way to know how much to amplify the signal?


texts: Why the implementation of current sensing network (CSN) by sensing the switch current is simpler than that of sensing inductor current?

texts:
The excerpt below is from the book Pulsewidth Modulated DC-to-DC Power Conversion: Circuits, Dynamics, and Control Designs by Byungcho Choi.

It looks a bit long but my main question is why the implementation of current sensing network (CSN) by sensing the switch current is simpler than that of sensing inductor current?

  Current mode control can be implemented in many different forms. The
  most popular  among them is the peak current mode control, illustrated
  in Fig. 10.6. In this control  scheme, the switch current is utilized
  in place of the inductor current. The switch  current, which
  corresponds to the on-time inductor current, is sensed through CSN
  and blended with the compensation ramp. The peak value of the switch
  current, or  equivalently the peak value of the inductor current, is
  used to determine the instant to  turn off the switch; thus, the
  control scheme is called the peak current mode control.  It should be
  noted that the switch current sensing is functionally identical to the
  inductor current sensing because the peak value of the inductor
  current is employed  as the criterion to turn off the switch.  There
  are several advantages in sensing the switch current rather than the
  inductor  current. The first is the simplicity in CSN. An
  implementation of CSN for the peak current mode control is illustrated
  in a later example. As the second advantage, the  sensed switch
  current can be used for the over-current protection for semiconductor
  switches. Due to these advantages, the peak current mode control is
  widely adapted  to modern PWM dc-to-dc converters.


texts: Why aren't active headphones equalized to a flat frequency response?

texts:
Some headphones are 'active', with amplifiers built into the cups and requiring a power source (typically AAA batteries).

I then see many audiophiles discussing frequency response as a metric of how good headphones are, and they categorically dismiss most 'active' headphones such as the Dre Beats Studio.

However, with some op amps it would seemingly be fairly easy to equalize the input signal, pre-amplified, such that it could completely correct for the driver's frequency response and thus produce an extremely flat frequency response if desired (or not, such as bass boost or cut).

Is there something particularly difficult with doing so?

Frequency Response Graph http://graphs.headphone.com/graphCompare.php?graphType=0&graphID[]=1383&graphID[]=193&graphID[]=1263&graphID[]=853&scale=20

For example, for the Dre Beats Studio (blue line), perhaps the EQ circuit could provide +3db@750Hz, -5dB@1100Hz, +6.5dB@1300Hz, +5dB@1550Hz, -4.5dB@8.5kHz, and +14dB@15kHz, with the slopes tuned to best align the frequency response to 0db from 500Hz to 20kHz.


texts: Nyquist sampling rate with real and imaginary aliasing

texts:
I need to calculate the Nyquist sampling rate of the function \$x(t) = cos(6t)-sin(5t)\$. By definition the Nyquist sampling rate is the minimum value of \$\omega_s\$ that yields no aliasing distortion. This is usually \$2\omega_{max}\$, which is generally the bandwidth.

However, the fourier transform of this function is \$F(\omega) = \pi(\delta(\omega+6) + \delta(\omega-6) + i\delta(\omega-5) - i\delta(\omega+5)\$. Unfortunately the graph for this cannot be shown, but this yields two real impulses at \$\omega = 6,-6\$ an imaginary impulse at \$\omega = 5\$, all with height \$\pi\$, and an imaginary impulse at \$\omega = -5\$ with height \$-\pi\$.

Therefore, I have two options for my nyquist sampling rate... Either \$10 \frac{rad}{sec}\$ or \$2 \frac{rad}{sec}\$. If I do choose the first option, this will allow for the impulses never to cross each other.

However if I do choose the second option, eventually the imaginary portion will cancel each other out due to the aliasing, and the two real impulses will cross each other. However, since the two real impulses are exactly the same amplitude, would this be considered aliasing? Also, isn't it good if the two imaginary impulses cancel each other out? Or would this all be considered aliasing?


texts:
I am studying Kirchhoff's Law on my book and I noticed some examples.

As seen on both pictures, there are + and - signs on resistors and they decide current's direction. I don't understand how can we decide their signs? Current flows through + to - but in first picture ic flows in opposide direction. In second picture they look like assigned randomly. We just randomly assign these signs? I am really confused.


texts:
I have a garage remote control I'm trying to duplicate, but the 433Mhz cloner I bought isn't responding to it.
Can anyone please confirm my remote is using 433Mhz frequency based on this circuit board image ? If not what frequency is it using ?


texts:
I want to get an impedance vs frequency graph for a capacitor in AC sweep analysis. I saw that there is an 'Impedance(1,2)' as shown in this picture in the Modify Trace window under Plot window templates:

Can someone tell me how to use this and also if I can get Impedance vs. Frequency graph using this? If you know any other way to get the required graph please do share.


texts: Where do RF common-mode interference currents flow?

texts:
In order to properly deal with EMI interference problems one needs to understand where/how the offending currents flow. With grounded balanced audio equipment, for example, common practice is to shunt RF common-mode noise that makes its way into the signal through cables to the chassis, where I always assumed it traveled to earth through the ground cable. I viewed an earth connection as a giant sink for this current, thinking that for whatever reason, RF common-mode current picked up by cable shields etc tries to find the fastest path to earth ground, and doesn't return to the source like it would with normal differential mode currents. But aircraft and ground vehicles don't have an earth ground connection, so clearly that isn't correct. So how and where do these RF CM currents flow when they are shunted to the equipment or vehicle chassis? Do they have the tendency to want to return to their source and flow in loops or just dissipate?

Update: Anybody??


texts:
I ordered this power supply unit to provide 3.3V filtered power to a video transmitter.

I attached the input and output power leads, soldered the proper voltage selection pads, and it works as advertised.

But I'm curious as to what the "signal" circuit does.  Can anybody load me a clue?


texts: How a wheatstone bridge is used in operational amplifiers?


texts: Schmitt Trigger for logic level conversion voltages up to +-20V

texts:
I want to be able to safely convert any voltages above a threshold voltage of +-1V with a maximum voltage level of +-20V to the logic level (3.3V). I ended up using an op-amp to construct a Schmitt trigger with the resistors and the power supply for the high threshold voltage of ~1V and the lower threshold voltage of ~0.5V. The circuit is shown below

Upon building this circuit using a LF353N op-amp and testing it out, I found that the output of the circuit just hits a DC level of about 3V when the input passes a voltage of 6V peak-peak. I also found that the waveform it produced was has curves on the top looking a bit like this:

The frequency of the waves I'm dealing with are around 10kHz - 100kHz and I was wondering if these effects are due to the fact that the slew rate of the LF353N is too slow?


texts: Impedance Mismatch of LVDS Differential Pairs

texts: A mistake was made when designing a set of mother and daughter PCBs, resulting the daughter board to have its LVDS pairs at ~100Ω differential impedance, while the motherboard ~90Ω. The receiver, which is on the motherboard, is a standard LVDS receiver, with 100Ω termination resistors. Those pairs connect via a dedicated FFC cable. The designs are already at the manufacturer and cancelling the order will cost a lot. What are the chances that the communication will survive this mismatch? The clock of the data transfer is between 300-400 MHz.


texts: I am running windows 7 professional 64-bit and up until this week was running MPLAB 8.92 IDE.  Now I get a brief look at the splash screen and the IDE refuses to launch.  I downloaded and ran the latest version of MPLAB X and it runs, but doesn't like legacy projects with "spaces or odd characters" in the pathname.  Has anyone else had this problem?  I have tried the normal sources - Microchip forums, Googling, etc, and although there are examples, none of the solutions have worked.  I have tried uninstalling and re-installing, running as administrator, using the -noswitch option.  Any help would be greatly appreciated.


texts: What about MCP23S17 GPIO pins output ports being also used to be read by input pins?

texts:
We are connecting Raspberry Pi3B with some MCP23S17 expanders:
MCP23S17.

I have read that they could emulate an open-drain outputs, playing with high Z state of the pin when configured as input. What kind of input and output those GPIOs are?

What about when it is a normal output by default? are they push-pull? I have seen that they normally are push pull output.

I would like to use that for continuity detection between two pins that could be or not in contact. So I would like to know what kind of things I must to do or connect there, when I will do some of these things:

1.- Could I connect an output pin to another input, write the output pin and read the input pin value?

2.- Does I need a special "connection-configuration" for achieving this function propperly?

According what I have been seen, it seems to be "open-drain" the best option, due push pull option it's said that it can't be connected with other IC pins. I'm not sure about this information.

So if anyone could clarify me these questions will be helpful.


texts: Core and winding dimensions for an electromagnet and bifiliar winding

texts:
I am making a powerful electromagnet for repulsion for my project. I made some electromagnets with iron core diameter of 1 cm, 1.5 cm and 2 cm for each 6 cm and 8 cm length. Different gauge enameled copper wire I used is 0.42 mm, 0.70 mm and 1.0 mm. Winding width is 1 cm for each electromagnet.  The end result is an electromagnet with 2 cm x 8 cm dimension with 1.0 mm wire gauge is the most powerful of all. But still not enough for what I want.

Now I am going to experiment with using 4 cm, 6 cm, and 8 cm diameter iron core of 8 cm length.

My question is: is there any rule/what is rule to decide winding dimensions in relation with core dimensions? As I used 1 cm winding diameter with wire of 1.0 mm and 2 cm diameter core. Will increasing the winding diameter say using 1.5 cm winding instead of 1 cm on an increased 4 cm diameter core will make a more powerful electromagnet?

I am also thinking to make an electromagnet with this same dimension as of my current best electromagnet (i.e. 2 cm x 8 cm with 1.0 mm wire gauge) using bifiliar winding (winding with two wires together and attach the ends) to compare both. As I read winding this way decreases overall resistance of wire, input more amperes & increases power of electromagnet. Any comment about this ?

I find this one online simulator for air core online electromagnet calculator. It's very helpful for finding resistance of coil and number of turns for cored EM too. Is there any such simulator available for electromagnets with core?


texts: Install DC power cable connector on vacuum feedthrough rod

texts:
I would like to know how to install an electrical plug or connector on an electrical vacuum feedthrough. An image of the feedthrough can be seen here: https://us.trinos.com/vacuum_s/trinos-electrical-feedthrough-weld-adapter-from-ht.html

You can click on the small image to see are larger picture of the feedthrough. I know how to make electrical connections on the vacuum side, I just need to connect a DC power cable on the atmospheric side. I would be grateful for any advice on the subject.


texts:
Now first and foremost, I know absolutely nothing about circuitry -  joined an computer science chatroom and they couldn't help, I have cross referenced the symbols to the internet to try and understand myself - and I still fail to understand. I must resort to asking here, so sorry for polluting this area with a question which will only benefit me, rather than benefitting the community.
that said:
I am trying to restore a 1970s synth, manufactured in italy, with my father.
Nethier of us know any circuitry.
We just want to repair the switch board, that is all.
I BELIEVE from my research, that the switches are DPST latch switches each has 2 sets of 15 pins to save you counting.
I have ONE question. Which circuitry diagram matches the photo of the switch board circuit?
Once we know which page we need, then we can get to work and use google for everything else!
Thanks in advance
(sorry for the abnormally large photos, I have downsized them twice already! This will stop you needing to learn forwards though) (the soldering was not our handy-work)
SBC->

v BACK v

page 1

page 2

page 3

page 4

page 5

EXTRA PHOTOS:


texts: I used to work at this electronics assembly plant in Arizona, and the machines there used reels of SMT parts that were like a bucketed plastic ribbon with a peel-off plastic seal. I don't know what those are called; most of them held tiny pieces of the basic elements of circuitry. Occasionally though I saw some moderately sized BGA chips and the like, eg. Xilinx chips that came in these ribbons as well. I'm curious if Intel sells ribbons like that filled with 6700K chips or something, probably to Dell or some other manufacturer. How about AMD selling ribbons of say G-Series SOCs, or any other massive chips or parts that are sold in literal reels?


texts: Maintaining Zener voltage @ 0.9 of Zener voltage

texts:
I have a strange question (at least to me.)
Suppose I have a Zener diode, to be very specific, 1N5234B.
It has a Vz = 6.2V, Izk = 0.25mA, Iz max = 80.645mA.
Suppose I have want that Zener to maintain 90% of its Vz, AKA Vout = 0.9 * Vz = 5.58V in the following circuit, and I want to calculate the load resistance that will satisfy this equation if possible.
Is that even possible?

I tried using Izk in my calcuations, and things turned out fine on Multisim, but I do not believe that is true, is not Izk supposed to be the minimum current value that will hold Vz at 6.2V?
Here is another picture of the Multisim results, and Iz is less than Izk.
What did I miss here?


texts: Controlling external appliances with a microcontroller by replacing switch with relay

texts:
I am working on a custom school project where I want to control a coffee machine's power using a micro-controller.

I have never worked with interfacing to external appliances like this before so please bear with me as I describe my question.

My idea for this problem is to replace the switch with some sort of relay configuration, in order to control the power flow with my micro-controller's output. I've done some research and believe I am working with an SPDT switch. It has 3 pins, the first pin connected directly to the power line, the second pin connected to a heating element, and the third pin connected to the heating element and ground.

I've also found a relay at my local store that I believe should work (please tell me if I'm wrong). It can be found here: http://www.alliedelec.com/search/productdetail.aspx?SKU=70133525.

I am able to produce a 5V output from my micro-controller which I plan to use as the control signal for the relay.

This being the first time I've worked on this type of application, I want to make sure I understand how to transfer the wires from the switch to the relay correctly before I go about testing my configuration.

Here's the coffee machine's switch and wires:

and here is the relay's schematic:

From what I understand the wiring should be as such:

Single black wire (top pin of switch)
Black and blue wire (bottom pin of switch)
Control signal from micro-controller (providing 5V)
Red wire (middle pin of switch)
Ground (provided by micro-controller)

Would this configuration be correct? Please let me know if I should try anything else or if any additional information is needed.


texts:
I am seeing that both of the analog signal and alternating current is represented by the same graph:

As far as I think I know, an alternating current travels back and forth with gradual changes in voltage but an analog signal over say, a telephone line is sent via DC Current.

So, is it the DC current that is changing in voltage when an analog signal is being represented this way?


texts:
Newbie here who is going to try his hand at replacing a BGA chip on a laptop motherboard.

I have ordered a new chip: NVIDIA G84-950-A2, and want to confirm some temperatures.

Based on some reading, I am thinking that I need to heat the underside of the board to about 190C at about 1C / sec.

Then heat the top to about 240C at a similar rate?

Does that sound about right?


texts: Can TPS3700 undervoltage overvoltage monitoring IC drive relay directly?

texts:
I am new to electronic circuit design. My current project is to monitor biasing voltage for under/ over voltage using IC from TI: TPS3700. If any of the under/over voltage occurs I will need it to drive a relay coil to cut off the main circuit supply.

I have studied the TPS3700 datasheet and found out its output pin is open-drain type and able to sink around 40mA of current. Could I connect NEC UA2 relay coil (pin8) to one of the TPS3700 output pin. This relay has coil current around 20mA and will have separate 5V supply connect to its pin1. My idea is to sink the relay coil current via the TPS3700 directly.

Another concern is will the relay switching noise coupled into the biasing voltage which is being monitored?

datasheet for TPS3700 and NEC UA2 relay
http://www.ti.com/lit/ds/symlink/tps3700.pdf
https://www.nec-tokin.com/english/product/pdf_dl/mini_data/relay_ua2_ub2_e.pdf


texts: Schneider Micom P123 trigger Output Relay

texts:
I am testing a Micom P123 relay with IEC103 protocol. I was able to communicate with 3rd party free Protocol Analyzer, Vinci. I was able to get Digital Input status. So communications is working good. The problem is I cannot trigger any of the output relay (there are 8 relays in this device). Specification for Control Direction is as follow (which is very vague for me):

General Commands (ASDU 20) (Control direction): Availability
− Auto-recloser On / Off: only on MiCOM P123: P123
FUN<160>;INF<16>, TYP<20>, COT <20>
− LEDs Reset: This command acknowledge all alarms on Front Panel on MiCOM P12x products:
FUN<160>;INF<19>, TYP<20>, COT <20>,<ADDR> P120 to P123
− Setting group number 1: FUN<160>;INF<23>, TYP<20>, COT <20>,<ADDR> P122-P123
− Setting group number 2: FUN<160>;INF<24>, TYP<20>, COT <20>,<ADDR> P122-P123
− Order TC COMM1: FUN<168>;INF <234>; TYP <20>; COT<20>,<ADDR> P122-P123
with private option inactive: FUN<160>;INF <136>; TYP <1>; COT<20>,<ADDR>
− Order TC COMM2: FUN<168>;INF <235>; TYP <20>; COT<20>,<ADDR> P122-P123
with private option inactive: FUN<160>;INF <137>; TYP <1>; COT<20>,<ADDR>
− Order TC COMM3: FUN<168>;INF <238>; TYP <20>; COT<20>,<ADDR> P122-P123
with private option inactive: FUN<160>;INF <138>; TYP <1>; COT<20>,<ADDR>
− Order TC COMM4: FUN<168>;INF <239>; TYP <20>; COT<20>,<ADDR> P122-P123
with private option inactive: FUN<160>;INF <139>; TYP <1>; COT<20>,<ADDR>
− Trip TC: FUN<168>;INF <1>; TYP <20>; COT<20>,<ADDR> P120 to P123
with private option inactive: FUN<160>;INF <142>; TYP <1>; COT<20>,<ADDR>
− Close TC: FUN<168>;INF <2>; TYP <20>; COT<20>,<ADDR> P120 to P123
with private option inactive: FUN<160>;INF <143>; TYP <1>; COT<20>,<ADDR>
After executing one of these commands, the relay sends an acknowledge message, which contains the result of command execution.
If a state change is the consequence of the command, it must be sent in a ASDU 1 with COT 12 (remote operation).
If the relay receive another command message from the master station before sending the acknowledge message, it will be discarded.
Commands which are not processed by the relay are rejected with a negative acknowledge message.

I tried Sending Fun 160, Inf 143, but still nothing. Tried asking Schneider too, but they are pretty much unhelpful to the max. If anyone has experience on this, pls do share. Thanks.


texts: High current draw effect on low current components?

texts:
Suppose i have a circuit like so:

High Capacity PSU +............... 100mA component (CA) .............. 5A component (CB)
     |                                        |                                   |
     - .......................................................................... -

CA is a device with lower current rating (100mA) than CB (with 5A rating). Suppose CB draws current while CA is operating. Will the high current burn CA? If so what would remedy this problem?


texts:
I have a bass amp with a blown fuse. A continuity test indicates a connection between the ground and the output of the transformer (circled in red and green on the right hand side of the schematic below). Resistance between the transformer ground and outputs (both) was about 0.5 ohms.

Is this an indication of a problem, or is this expected?

The amp is an Ampeg BA-115


texts:
This is slightly modified diagram of original one for control of DC motor using relays I got in this community. I added flyback diodes and battery for relay coils:

My question is, is it possible to wireless control switches S1 and S2 from distance of few meters and what is easiest way to do it, if it is possible?

EDIT:
I modified circuit, now there are only two wires for motor and limiters.
Functions of RLY1 and RLY2 are also changed: when RLY1 is "activated" (RLY2 "deactivated") it will move motor in one direction, when RLY2 is "activated" (RLY1 "deactivated") it will move motor in opposite direction.


texts:
I have 2 input pins i1 & i2 they drive a motor forward and reverse by switching states
if i1 is 0v then i2 is 24v forward state
If i1 is 24v then i2 is 0v reverse state
Capable of delivering 3A

I want to change this to 3 pins
o1 = 24v
o2 = 0v
o3 = 0v      in forward state

o1 = 0v
o2 = 0v
o3 = 24v.    In reverse state

Looking for the easiest solution, was thinking 2 diodes ( is that possible)

Voltage is DC


texts:
I am trying to explore PID control with a simulation. My problem is that the derivative term does not behave as expected in my simulation: No matter how large its coefficient it seems unable to prevent overshoots.

I tried to tune the system with the Ziegler-Nichols method and using the parameters the should produce "no overshoot" according to the Wikipedia entry of the Ziegler-Nichols method.

My "process" is simply the 5-sample exponential moving average of the PID controller output. Controller output is limited to [-1,1]

Can anybody see what the problem with this code is:

PVset = 0.5;            % set point for process variable

steps = 100;          % time periods/steps to simulate

PV = 0;               % process variable (time series)
error = 0;            % error in PV (time series)
der = 0;              % derivative of error (time series)

Ku = 1;
Tu = 2;

Kp = Ku*.2;
Ki = 2*Kp/Tu;
Kd = Kp*Tu/3;

for k=2:steps
    % calculate error
    error(end+1) = PVset-PV(end);
    % P term
    delta = Kp*error(end);
    % I term
    delta = Ki*sum(error) + delta;
    % D term
        % instantaneous derivative time series
    der = error(2:end)-error(1:end-1);
        % average derivative over x periods
    per = 4;
    if k >= per+1
        avgDer = mean(der(end-(per-1):end));
        delta = Kd*avgDer+delta;
    end
    % limit PID controller output to -1 -> 1
    if abs(delta) > 1
        delta = sign(delta);
    end
    % simulate process behaviour
    p = 5;
    PV(k+1) = (p-1)/p*PV(k-1) + 1/p*delta;
end

figure
hold on
plot((0:steps), PV)
plot((1:steps), error, 'r')


texts: Astable multivibrator with increasing frequency

texts:
I am wanting to design a circuit that uses an astable multivibrator as a clock source. However the difference being that over time the clock is gradually sped up until it reaches some multiple frequency.

I have found circuits that have a speed that that decreases to zero (an addition of a cap) but not one that speeds up.

Any ideas or help to point me in the right direction would be great!
Thanks
jme


texts: What is the maximum voltage of a coin cell battery?

texts: The nominal voltage seems to be 3V for a coin cell battery (e.g. motherboard battery), but what the maximum of a fully charged battery fresh out of a package from the factory?  What is the theoretical max?


texts:
What are the advantages/disadvantages of compensated and uncompensated op amps?

Thank you in advance.


texts: Why does DSPIC33F restarts when timer interrupt flag is addressed?

texts:
I have a peculiar problem with the timer on the DSPIC33F. I need to create a delay function and I have decided to use Timer 2 to count the number of instruction cycles. The function would enable the timer and then wait in the while loop waiting for the interrupt flag to be set. See code below:

T2CONbits.TON = 0;                  // disable Timer 2
IFS0bits.T2IF = 0;                  // reset Timer 2 interrupt flag
TMR2 = 0;                           // reset timer accumulator
T2CONbits.TON = 1;                  // enable Timer 2

while(!IFS0bits.T2IF);              // Wait until until the timer 2 timeout
IFS0bits.T2IF = 0;                  // reset Timer 2 interrupt flag

T2CONbits.TON = 0;                  // disable Timer 2

The function works perfectly fine if the TMR2 interrupts are disabled. However, if the TMR2 interrupts are enabled, the firmware restarts when the interrupt flag is set. This restart only happens when I run through the code, but not during the step-by-step execution (I am using the ICD3 with MPLab 8.something). I did not setup the ISR for TMR2. All other interrupts are disabled.

Even though I have achieved my goal of creating the delay function, I am still wondering about the possible reasons for the firmware restart. Is that because for some reason I can address the interrupt flag only inside the ISR? Or are there any other reasons?


texts: How can I combine two antennas that carry different frequencies?

texts:
I have two antennas:

antenna 1 carries CATV signals channels 2-29 which I believe use carrier frequencies from around 55.25MHz up to 253.25MHz
antenna 2 carries OTA HDTV signals on UHF channels 21-49 which I believe use carrier frequencies from around 513.25MHz up to 579.25MHz

Other than using an antenna switch how can I combine these into 1 input?

I've tried using a basic antenna splitter/combiner but the tuner has a hard time picking up many of the channels. Why does that not work? I assume its because there is unwanted signal beyond each of those spectrums that creeps into the signals from the other antenna?

Is there equipment to cleanly filter out the unwanted bands and recombine the ones I want?


texts: Is it possible to run EagleCad's DRC from a terminal, and pipe the error list to a file?

texts:
I currently use EagleCAD to capture my schematics and route my circuit boards. Eagle isn't very pleasant to work with, so I've started working with schematics and boards outside of Eagle's GUI by directly editing the SCH and BRD files; calling Eagle commands from the system command line when needed. (Just to be clear, I mean calling Eagle commands from an external script or a CMD or terminal window, not from the little textbox "command window" inside the Eagle GUI.)

I'd like to be able to handle DRC and ERC from outside of the Eagle GUI, but I'm unsure how. I can, for instance, call the Eagle DRC from the command line with "eaglecon -C DRC;QUIT; [board name]", but this just opens the Eagle GUI, lists any DRC errors in a dialog window inside the GUI, and then closes the GUI. I would like to get the list of DRC errors as text in the command window, so they can be piped to a file.

Any ideas if this is feasible? Thanks


texts: Is it possible to make a plastic touch screen as sensitive and accurate as a glass one?

texts:
I learned in this answer that touch screens with a glass front are generally more sensitive and accurate than those with plastic fronts. This corresponds with my personal experience.

However, is there a way to bring devices with plastic fronts up to the accuracy and sensitivity levels of those of glass? What would this require?


texts:
I am trying to create a super simple Low Battery alert monitor, by utilizing an open-loop comparator. LBO is active-low - it's connected to a TTL input pin of a uC, running from same Vbatt voltage.
The circuit's running from two series AA cells so I get 3.0V when it's fresh, and I want to create an alert when battery voltage (Vbatt) falls below ~2.15V.
Zener diode is Vz=1.8V @ 50uA.

I calculated the voltage divider R43/R46 so that it'll give that 1.8V threshold voltage when Vbatt reaches 2.15V, and indeed it does so. So whenever Vbatt>2.15 I get higher voltage on V+ than V-, but for some strange reason the comparator does not output its VCC, (I measure 0V on its output pin)
only when Vbatt reaches 3.3V (used a programmable power supply) and so V+=2.75, V-=2.11V I detect that the comparator is switching to output VCC.

Why does this simple circuit doesn't work? Why does this comparator needs >0.6V difference between
V+/V- to switch its output to high? Is there some parameter I am missing?
Can I solve this issue without changing the circuit (only resistor values)?

simulate this circuit – Schematic created using CircuitLab

Info:

U5 comparator is Diodes AP331A chose it because it can run from single supply down to 2.0V which matches the whole idea.

D1 zener is DDZ9678


texts: GNSS module direct grounding to ESP32 increase sensitivity

texts:
I have a simple cirquit that composes of the following :

ESP32-DevKit-LiPo (ESP32-WROOM)
GNSS Module Beitian BN-357P with ufl connector for external antenna
GNSS Active Patch Antenna

My simple is schematic is as follows

I program the esp32 to bridge the bluetooth to the GPS Uart so I can read the NMEA messages from my mobile with the help of GPS Bluetooth Aplications.
During Installation ia small box I installed a small pla thin sheet between the module and the esp32 so not to have a short cirquit.
These are the stats I had:

Then I removed the insulation sheet and put the gps module upside down so its ground shield would touch the esp32 ground shield.

Then the satellite stats had great increase:

When the module didnt touch then the sattelite signal decreased significantly.
The pin to pin ground connection between gnss and esp32 is fine and the cable is about 5cm.
How is this explained?
Is somehow the ground connection more direct and "cleaner" ?
Maybe the bluetooth antenna proximity?


texts: Android NFC library - Command not recognized

texts:
To access more than 2kb of data from TI Rf430 transponder IC, a custom command (0xC0) in specific format needs to be sent. On sending the custom command, command not recognized (0x01) is the response received.

Custom command array => {flag, command, manufacturer code, Block Address LSB, Block Address MSB}. Does Android NFC library supports custom commands as mentioned above?.


texts: ARD00280 Microchip Energy Reference Schematic Live and Neutral Swapped?

texts:
Looking at the Microchip Energy Chip reference design

I noticed that the power is being sampled from neutral.  My first reaction to this was this is backwards, that the power should be sampled from the live. however, the guide talks about the concept of a live or hot ground.  what is the advantage of using a hot or live ground as the ground reference in such a design as opposed to sampling from live?


texts:
Assuming that logic 0 is available, show that the INCLUSION gate is a
universal building block.

I don't know what inclusion gate is.


texts: I have two perfectly good CPUs-one a Pentium m, the other a Pentium III-and they're just sitting in antistatic bags and bubble wrap doing nothing. I want to use them for SOMETHING, I know their pin-outs and stuff, but I don't know how to get them to do things. I want to make my own motherboard and make them behave like a microcontroller with them communicating with GPIO chips of some sort, but without the obvious loss in performance (since MCUs are slower than CPUs). Can anyone help me get a grasp of what I need to do? I also need the assembly language for both CPUs.


texts: Convention for Transfer Function Poles and Zeros

texts:
I'm learning about transfer functions, and I'm trying to understand the convention for getting poles and zeros from the transfer function. Let's say I have a transfer function:

\$H(s) = \frac{1}{(s+3)(s+2)} = 1/6*\frac{1}{(s/3+1)(s/2+1)}\$.

Are the poles of this transfer function -3 and -2, or +3 and +2?

Looking at links like http://en.wikipedia.org/wiki/Pole%E2%80%93zero_plot, it would seem that poles are supposed to make the denominator zero, so that would suggest the former.

But looking at links like http://www.onmyphd.com/?p=bode.plot, the poles would +3 and +2.

Are there two different conventions? Thanks


texts: PIN Diode T-R Switch for use with RF Power Amplifier

texts:
I would like to use PIN Diodes to actuate the T-R switching of my RF Power Amplifier, however, I am having trouble understanding the proper way to accomplish this. I would rather use a solid state switching method over mechanicals relays to save space, and achieve faster switching.

Approximate Specifications:

50mW Input (50Ω)
~30W Output (50Ω}
146MHz
12v Power

This is what I have found as the general go-to, however, since I will be using a transceiver I haven't figured out how to adjust it for my application.

This is a block diagram of what I'm trying to do but I'm not sure how to actually make it work. While the transmitter is on the path needs to go to the PA module, and of course be isolated from the output/antenna to not cause catastrophic oscillations. If I use a shunt and a quarter wavelength transmission line won't this interfere with the operation? Would I maybe have to use two quarter wavelength lines on both sides of the "RX" leg?

However, during RX I need to block the path to the input of the amplifier and connect up straight to the antenna. Should I just use a transistor to turn off the PA bias? If I shunt the output of the PA during RX I believe it would just shunt the antenna as well, wouldn't it?

I think I'm just getting confused as to how to properly implement this system. I've spent plenty of time googling PIN diode switches but can only find a "simple" T/R switch, and not one for use with a PA in between.

If I was using a relay I'd use a DPDT type, and maybe a transistor to turn off PA bias, right? So how do I implement this in terms of PIN Diodes?


texts: I have no idea what this part is called. I want to figure out if I can remove the wire out of it and slide in the other broken end before soldering it the board. Is it reusable, or do I need to buy another one? (e.g. because it's heatshrinked or something)


texts:
I designed a Buck Converter for my senior design and need to put that on PCB which will power up the circuit.

I calculated the with of the trace for the current I need which is 8 Amps. Based on the calculation I need 0.13 inch of trace. My question is do I need to make the thickness of the traces same for the Capacitors as well or only thick traces  for input and output of the buck converter. Since, capacitor only holds the voltage, I don't see the point of making the traces bigger for the capacitor. I need to make sure that my assumptions are right before I make the PCB order. The schematics of the converter and the traces are down below.


texts: Does ground suffer from a voltage drop like effect?

texts:
I am currently working on a project where I need some very long wires (about 20 meters, and that is 40 meters both ways), that will be connected to a button which will be used to trigger a pin on the controller (ATmega8).

Due to expected voltage drop problems, I have chosen that I will pull the I/O pin high, and run ground through the button (button pulls I/O pin low and triggers it).

Hence my question: Will there be any problems using such long wires when I run ground through them, instead of Vcc voltage level (5V)?

Does ground suffer from "voltage drop" like problems?


texts: Why sometimes a stepper winding is not fully powered?

texts:
After some tests with my multi-meter I was quite surprised that the windings of my stepper was not receiving the full current (1.5 A) even if the driver board was set so.
After mumbling and scraping my head for some days, I've found on the driver datasheet that in full-step mode only around 70% of the current is provided to the windings (see image below).
Later I checked other datasheets from different chips than the Allegro A4988, and it seems that this is a common approach.
I was pretty sure that in full-step mode the rotor was jumping from one stator-tooth to the next at 100% of the current. But it seems that I was completely wrong: the rotor is stopped between two teeth powered at 70%.
Why this choice? In this way more holding torque is offered by the magnetic field, or what?
On the other hand, half-step mode allows 100% of the current on one tooth while cutting off the current to 0% on the next one. This mode will offer less torque?
I'm again scraping my head... I'm a little bit confused about what mode to choose to get the max holding torque when the motor is stationary with a fixed load...

EDIT: my modified table:


texts: Power source switching/isolation circuit

texts:
I'm currently designing device which will be powered from external PSU but also will have backup power system from battery. I'm trying to solve my problem.
When external power source is down (5V - USB), I'm switching to battery source. Battery powers my 3,3V power line through LDO regulator. At the same time boost converter turns on and powers my 5V bus. I have problem that external 5V source (USB) is connected directly to my main 5V bus, same as my boost converter. Where is problem? Charging circuit is also powered from 5V bus (USB), that means battery will charge itself, it'll drain quickly.

I want to note that only one source will work at the same time, there are additional switching circuits which will take care of it. There is no possibility that boost converter will be working when external source is connected.

I came with such idea like on picture above. However I'm bit suspicious, will it work? N-channel mosfet is "inverted" and I'm unsure how it will behave in real life scenario. I tried it with simple simulation and it somehow work, but it's just simulation... Any advices are welcome. I'd like to keep it simple as possible. If 5V bus wouldn't be critical, I'd probably just use diode, but I need to keep it as close 5V as possible at this stage of design.
Falstad:* (n-channel)
(p-channel)
*when top source is 5V, right source is 0 and vice versa
Also piece of main schematic I'm working on

I was also thinking about doing same thing with NPN transistor, but I'm unsure because of power losses and current ratings (this part of bus consumes up to 200-250mA),
In tl;dr I want to avoid powering a piece of power bus, isolate it.


texts:
I have a little project going on, that involves turning on and off a led strip.

The led strip specs :  5M Led SMD 600 Lights
LED : 3528 SMD
600 Lights, 5m : 120 LED / m

According to this site, it will drain 48 watts for the full length.
I am looking to use about 0.5m and power it through a 9V battery. According to this site, the current that the strip will drain will be :

Wattage / Voltage = 4,8W / 12V = 0,4 A

I am not sure if I should be using the 9V as the denominator, but either way I am looking at about 0.5 Amperes.

My Question :

A 9V MN1604 6LR61 alkaline battery provides with 560mAh, which gives me roughly 1 hour of battery life.

I know that BJTs can amplify the current, by providing a base current and getting it amplified at the emitter/collector.

Ib will be Ie / hFE , so I am reducing the current I drain from the battery hFE times.

simulate this circuit – Schematic created using CircuitLab

(resistors chosen randomly)

So what is wrong with this picture? I must be making a mistake otherwise I am generating the missing power out of thin air.


texts: How can I debug/get output from a microcontroller using cc-debugger?

texts:
I am working with TI's CC2540 SoC using CC2540dk-mini. My software stack is:

Ubuntu 12.04
sdcc Compiler
cc-tool to flash programs onto board using cc-debugger

I can compile, build and flash firmwares perfectly (until now) using these tools. But I do not know how to debug (toggle breakpoints, see sfr values, etc.) or even to "print" from CC2540.

Chapter 3 from CC2540 user guide talks about the debug interface, and reading it I notice that flash programming is done using this interface. So... aparently to debug the firmware I would have to extend cc-tool. It sounds right?

About printing: reading the sdcc user guide (section 3.17.2.1) I realize that I have to provide putchar() function, which makes sense. But what low level protocol should I use? USART? Or something else? (debug interface?) How the CC2540 can talk with cc-debugger? How cc-debugger can talk with Ubuntu?

This all seems a little vague, but it is because I have no experience in this "field" (I always used Arduino and I never had to go in this "low level" before).


texts: I am going to use a 3V DC motor (operating voltage 1.5 to 4.5V DC) and MSP430G2553 microcontroller. So which digital potentiometer should I use to control the speed of the DC motor?


texts: I need to write a verilog code to generate a signal which goes high for one clock pulse after every tenth clock pulse

texts:
I need to write verilog code wherein I need a signal which goes high for one clock pulse after every tenth clock pulse.
I tried something this way,
    module top  #(
                  WIDTH=8
                 )
                 (
                  input clk,
                  output reg sig1,

                  );
     reg [WIDTH-1:0] count;
     always@(posedge clk)
     begin
      count <= count + 1;
      if (count == 'd10 || count == 'd20 || count == 'd30 || count == 'd40 )
       begin
         sig1<= 1;
       else
         begin
          sig1<= 0;
         end
    endmodule

This code works fine and is able to produce the required signal 'sig1' which goes high for one cycle after every tenth clock cycle.
Is there any better and generalized way to generate 'sig1' with the required characterstics?
Note: I intend to use this signal 'sig1' in a larger design which needs to be synthesised.
I got few ideas from the comments below:
    module top (
                input clk,
                output sig1
               )
    reg [3:0] count;

   always@(posedge clk)
    begin
   if(count == 'd10)
    begin
     count<=0;
     sig1<=1;
    end
   else
     begin
      count<=count + 1;
      sig1<=0;
     end
    endmodule

I got this code with much better approach, more suggestions will be appreciated.


texts: Can anyone explain the ohm's law apply here?

texts: What i am seeking is to explain why the relationship here is not V2/R2 instead it's given as (V1-V2)/R2


texts: Calculation of DC power drawn by circuit in Class A power amplifier

texts:
simulate this circuit – Schematic created using CircuitLab
I'm watching Prof. D.C. Dube's lecture (timestamp included) on power amplifiers, and I'm confused about the calculation of DC power \$P_\text{dc}\$ in class A amplifiers, like in one shown in the above schematic. I do understand that we take the following approximations:
$$i_\text{C(min)}=0$$
$$i_\text{C(max)}=2I_\text{CQ}=i_\text{C(sat)}$$
$$v_\text{CE(min)}=0$$
$$v_\text{CE(max)}=2V_\text{CEQ}$$
and that the AC load line characteristics is like this:

DC Power \$P_\text{dc}\$ calculation
$$P_\text{dc} = V_\text{CC}I_\text{CQ}$$
Now, from what I understand \$P_\text{dc}\$ is defined as the average DC power drawn by circuit at the collector (power consumption by biasing resistors is ignored).
Confusion:
Why are we writing the DC power as \$V_\text{CC}I_\text{CQ}\$ rather than \$V_\text{CEQ}I_\text{CQ}\$? \$V_\text{CC}\$ is the maximum value of \$v_\text{CE}\$ when the AC signal is applied. But in the absence of the AC signal (we're calculating DC power after all, so AC signal swing can be neglected), the maximum DC voltage signal at collector should be \$V_\text{CEQ}\$, no? That is, basically I suspect that the DC power should have been
$$P_\text{dc} = V_\text{CEQ}I_\text{CQ} = \frac{1}{2}V_\text{CC}I_\text{CQ}.$$
Do we take \$V_\text{CC}\$ rather than \$V_\text{CEQ}\$ because we include the power consumed by resistors \$R_C\$ and \$R_E\$ in DC power drawn by circuit as well?
Could someone clarify?


texts: How should I wire two batteries to make my mobile DVD player work longer?

texts:
I have a plain old mobile DVD player (Apex model PDVD-937). It runs on a single rechargeable battery supplying 1600mAh at 7.4V. I would like to augment it so that it can work for a longer period of time.

I've recently purchased an additional battery that is compatible with the original, albeit supplying only 1000mAh. I would like to wire the two batteries together so that I can enjoy a larger charge (2600mAh?) and longer time for playing DVDs on the device.

Being a complete electronics newbie I am guessing I need to hook the batteries in a series, but I've run into a problem. Each of the two batteries have three wires coming out of it: Red, Black and Yellow/White. Here's what it looks like:

Assuming Black for negative and Red for positive, what is the Yellow/White wire for? How should I setup the two batteries to get the longer operating duration for the device?


texts:
I found this video which shows how to plot the transit frequency in Cadence Virtuoso. But on another site, instead of using c_gg, the capacitance used was c_gs+c_gd for the ft equation. Which is correct?

Also, the plot I'm getting in Cadence is around the hundred MHz to GHz range, which increases with increasing Vgs (if length is fixed) and decreases with increasing length (if Vgs is fixed). If I  want to have an amplifier with GBWP of 10MHz, which transit frequency should the transistor have? Should it be near 10MHz or as large as possible?


texts: Is there a function to model the resistance between 2 metal probes

texts:
I'm trying to design something that will measure the amount of rainfall in a small container. And I was wondering if there was a function I could use to calculate the resistance of the metal probes when say we've had 5ml of rain and then 25ml of rain.

With the output of these probes I can put these in a potiential divider and then a have a voltage output proportional to the amount of rainfall.

Is this a sensible approach to measure the amount of rainfall electronically?


texts:
I'm a complete novice when it comes to circuitry & electrical engineering. I'm more of a coder.  So I really appreciate your input, even if my questions are simple for some.

That being said, I need to power an RFIDLOG & auxillary logger from Priority 1 (http://www.priority1design.com.au/rfidlog_rfid_data_logger.pdf) from battery power.  I'd like the battery to last at least 24 hours.  The specs state 'maximum rate' for the set-up I am using is 88mA.  I plan on using a 12V battery.  It is really as simple as 0.088 x 24 = I need at least 2.1 AH in a battery?  So with a 6AH battery, I should get ~68 hours of use?  My colleague seems to think otherwise, that I might need a series of 6AH batteries to operate for at least 24 hours, but I can't find any information online that suggests otherwise.

Also, the unit specs say it can run off 6V-13.2V input.  Would be any benefit to using a step-down buck convertor to reduce voltage, or should I just connect the battery as-is?  I've had problems in the past with regulators interfering with radio signals, and the goal is to maximum the read-range of the antennas for 134khZ RFID tags.

Finally, is the best way to connect it just to solder wires to the V+ and V- inputs?  Or is it better to use some kind of socket-like adaptor?


texts: Efficient way of driving 10w LED with a 12v SLA battery?

texts:
I have a 12v SLA battery from an old UPS and two 10w led. I'm new to these stuff.

I connected one LED directly to the battery and in about 15mins it go hot and now one row doesn't work. I didn't know that we had to limit current to leds. So my question is, What is the most efficient way to drive this 10w led using a 12v SLA ? Adding just a resistor will waste about 2watts right ?

As I'm new to electronics, please draw me a circuit schematic :)


texts:
What would happen in a class a amplifier if I connect a capacitor in series with the load resistor (between power supply and the transistor collector)?
My goal was to block the dc qiescent current to reduce energy wasted as heat.

I apologize in advance for my english (i'm italian) an for my probably stupid question.