texts:
I somewhat know the answer to this question but just want to clarify. In order to design the impedance matching, I will need to know the load impedance and the source impedance to begin with. Correct?
Let's say I have a circuit designed which is the "load" circuit of my setup. How would I go about measuring its input impedance since this is what is necessary to design the impedance matching circuit?
I would also like to know of any easy-to-obtain software that may be useful for impedance matching. I am presently trying to get my hands on ADS from my university but if there are any other software which are helpful that you know off, that would be great.


texts:
Is it possible to write your own tool to program FPGA boards, or are they locked down to only be programming by the manufacturer's tools?

In other words, can I write my  own tool to program/flash a FPGA board which I purchase from a large vendor (say Intel, or Xillix).


texts:
I'm familiar with Assembly/C/C++, so this question is focused on the hardware side.

Context: I want to have a real time heart rate monitor so that I can see, on my computer screen, my heart beat. [Want to test biofeedback / controlling of heart rate.]

Now, I know that there are those runner's bands that people wear on their chest that provides an approximate heart rate every minute, and some of them even has a usb port to provide a time series after the fact.

However, I want real time data.

Question: Where can I get (what are these things even called?) a wireless device that can (1) measure my heart rate in real time and (2) broadcast it in wifi or bluetooth .. or anything I can pick up with a PC?

Thanks!


texts: What type of fuse should I use for this basic electronics design?

texts:
I'm creating a simple Arduino project that utilizes a solenoid and a rotary encoder. I'm powering the entire device with a 12V 5A switching power supply. I want to add a fuse to the design but can't figure out what capacity to use. My options (as far as I can find) are 200mA, 500mA, or 5A. I predict the device will draw a max of about 760mA so the 5A fuse seems sensible but also pretty high.

From what I've found, the devices will pull the following current:

Solenoid: ~580mA (based on 7W/12VDC)
Rotary Encoder: ~16mA @5V
5V Regulator on Trinket: ~150mA max

First, am I calculating the current draw correctly?
Second, is the schematic configuration sensible?
Third, what size fuse should I be considering?

Any help is appreciated!


texts:
I was able to calculate the package delay values in pico seconds by using the IBIS models from the xilinx site.
For example:
For a Virtex-5 FPGA IBIS model, the package ff323_5vlx20t_ibis.pkg is provided. Let us choose the pin B9.
From Capacitance matrix, C=1.58E-12 F/package length
From Inductance matrix, L=1.99E-09 H/package length
Delay= SQRT(C*L)=56.1 ps
Now I want convert this delay(56.1 ps) to package length(mils).
What method I need to follow for the same?


texts: Arduino - Voltage ladder and analog input pins

texts:
I have two questions:
1. Does the analog pin on the arduino board get the voltage or the amperage from the circuit I connect it to? (of course it's scaled to a value from 0 to 1023)

.2. I have this circuit:  http://i60.tinypic.com/fymxwm.png

Assuming you can only turn on one switch at a time (But also if someone turns on more than one switch, I don't want the whole thing to short out), it has a different amperage for each switch.
Now, if the arduino analog pin gets amperage, then I think this is ok.
But if it gets voltage, I've been told to use something called a voltage ladder, as it does the same thing but for voltage, here's my question that I asked before:  https://electronics.stackexchange.com/questions/99417/what-resistors-to-use-to-read-several-buttons-with-a-single-analog-pin

And my circuit and the circuit they gave me look pretty similar to me, are they the same?
Will my circuit also change the voltage due to Ohm's law?

Thanks.


texts: How to calculate a lithium-ion battery's discharge time at a specific load?

texts:
How do i calculate the discharge time for an lithium-ion battery at a specific load?

Let's say i have a lithium-ion battery with a nominal voltage of 3.7 V, a cut off voltage of 3.0 V and a nominal capacity of 450 mAH. The battery is discharged with a load of let's say 20µA.

Now i want to know how long it theoretically takes until the battery is discharged. Can I use the formula discharge time = capacity(mAh)/load(mA) as for (NiMH-) batteries?

Thanks in advance.


texts: How do I change the frequency of this Vibrato-Circuit?

texts:
I am currently looking at an old 60's Transistor Organ (Phillips Philicorda GM752 to be exact). It has an integrated Vibrato-Unit, although the only modifyable parameter of it is the depth (amplitude) of the Vibrato. My question is: Is there a way I can integrate some sort of potentionmeter into the circuit to change the frequency of the Vibrato?

The Service-Manual (which I've taken the schematics for the Vibrato from) is available here (It's written in German, but I can help translating if you have any questions)


texts: Wiring sets of 2, 15" LED strips to illuminated switch. 12 sets total -- to power supply

texts: Ok, Hoping you guys can help me. I have a screen printing machine for printing t-shirts. The machine has 12 arms that extend out from the center. Under each of these arms I want to put 2 15" white LED strips. So in total it would be 24 total strips. Each set of 2 strips would be powered by an illuminated push button switch on the end of the arm. My question is can I use one central power supply at the center of the machine to power all 24 strips? If so, can you recommend one. Or any other ideas how to complete this project. TIA


texts: Using the frame of an RV trailer for the ground

texts:
I have an RV travel trailer that I use a 2000W generator to supply power to the 30A incoming power socket. I have also added 2 × 100W solar with battery minder, a 3000W sine wave corrected inverter for electrical devices and replaced the original single 12V deep cycle with a pair of 6V golf cart batteries in series. The trailer has conventional (for an RV) electrical/propane fridge and is fitted with multiple 110V outlets for use when connected to the generator or municipal power. I've added a couple of (completely isolated) 110V outlets that are supplied by the battery bank through the inverter.

During sunny days, the solar is more than enough to keep everything happy; in fact, there is potential power being 'left on the table'. I want to add to my battery bank so as to take advantage of this but weight distribution (and trailer tongue weight) would dictate that I mount any new batteries to the rear luggage rack.

During my previous additions to the electrical system I have noticed that all 12V seems to be wired directly; i.e. one positive and one negative; the frame is not used as a common ground like an automobile. I was planning on paralleling additional batteries to the originals with 4 or 6 gauge AWS which can start getting expensive running the length of a 28ft trailer.

Is there any reason not to use the frame as the ground and only pass a single wire the length of the trailer?

Addendum:

The 3000W inverter was intentional overkill. The 3000W model had dual cooling fans, wattage and voltage metering, remote shut-off and two 12V ± inputs (two +, two -) on a bus bar. Smaller wattage models did not have all of these. While the parasitic power is slightly more than the smaller models it is a trade-off I can live with. I typically run 30-40W (ecostar TV and a tablet PC for a movie) although I have run an 8 amp (110V) wet/dry vacuum with no problem from an outlet powered by the inverter.


texts: PSpice: value of resistor controlled by a function

texts:
I am using PSpice to simulate the parasitic BJT of a power VD-MOSFET, which under certain conditions can be turned on and lead to the destruction of the cell.

I have designed a model that is working well enough, but it doesn't take into account the temperature rise because of the increased currents flowing through the cell. To achieve that, I have to add a resistor in parallel to the BJT (Rtc in the attached picture), whose value is changing throughout the simulation.

As I first step, I would like Rtc to be decreased exponentially with time.
Is there a way to establish and use a function like this in PSpice?


texts: Howto discharge a capacitor through an LED by removing the power

texts:
I'm trying to learn about capacitors (charging / discharging) so I've built a very simple circuit where I have an LED, a 220 ohm resistor and a 4700uf capacitor in series. Power supply is 5V. The idea is simply to see examine the charging / discharging behavior of the capacitor.  The circuit doesn't have any practical use.

When I hookup the power supply the LED lights up and then dies out completely as the capacitor is fully charged (as expected).

I was looking at a How Capacitors Work article where it was stated that by replacing the power supply (in their case battery) with a wire, the capacitor would discharge through the bulb.

If I want to discharge the capacitor through the LED I not only need to remove the power supply and replace it with a wire but I also need to reverse the polarity of the LED.

Now this makes sense if you look at the polarity of the LED and the capacitor.
As soon as I add a power supply I again need to switch the LED around.

Is this just because of the nature of the LED (it being a diode and only allowing current to pass in one direction). A DC bulb doesn't have this issue as it doens't have polarity and can be hooked up either way ? Or is my circuit / thoughts on this completely wrong ?

simulate this circuit – Schematic created using CircuitLab


texts:
A system is represented by the following equation:
$$\frac{^2}{^2} + 8\frac{}{} + 9 = 1$$

By taking the initial conditions, (0) = 1, ̇(0) = −1, draw a block diagram for the
system. The transfer function will be as following:

$$\frac{^2}{^2} + 8\frac{}{} + 9 = ()$$


texts: Is FR4 waterproof? What about soldermask?

texts:
I'm investigating ways of making a capacitive sensor that will operate in very moist environments, potentially even submerged. What I need is a way to make some conductive plates in a specific arrangement that are electrically isolated from each other and from the environment.

One of the options I'm looking at is to use a PCB. I would put the plates in the proper arrangement on both sides of an FR4 board using polygon pours and then cover the whole thing with soldermask. There would be no components on the PCB at all. The entire board, except for the external contacts (outside of the moist/wet sample), will be soldermasked.

Questions:

Will the soldermask block the moisture effectively, preventing the plates from forming an electrical contact even in the case of prolonged submersion?
Will the FR4 remain dry? Or will it soak up water, leading to an electrical contact between the plates?
If this is not the case, is there anything I can treat the board with to make it waterproof?

Let's say for the sake of argument that I will be using seeedstudio's Fusion PCB service.


texts: What causes sub-second mains voltage outages?

texts:
Many times I observed a following electrical event: mains voltage will suddenly drop and then immediately restore. This causes lights to blink and computers to restart.

I can't imaging what could cause such a short event. I mean if someone wants to open a switch on a substation (or somewhere else in the grid) they do it for some service operation that takes time, so it doesn't make sense to have an outage shorter than several dozen seconds. So to me it looks like electrical company servicemen just open a switch and then close it to play an evil joke on the customers.

What causes such short mains outages?


texts:
From this article: Power Tips: Power converter topology... they say that:

  Moreover, buck-converter duty cycles become extremely small in
  high-voltage AC/DC conversion. For a 440VAC to 15VDC conversion, the
  duty cycle could be smaller than 2% in a DCM buck converter. When
  operating the converter at a high switching frequency, it is possible
  to hit the controller minimum on-time limitation; for example, the
  UCC28911 requires a 420nS minimum on time. In other words, if you use
  the UCC28911 in a 440VAC to 15VDC conversion as a buck-converter
  controller, the converter must operate at a switching frequency lower
  than 45kHz.

What I understand is this. Let's say the duty cycle is 2%. If the switching frequency is 60 kHz, then the minimum time would be 0.02*(1/60k) = 333 ns. And the UCC28911 wouldn't start because their minimum time is 420 ns according to the datasheet. Then the article says that the converter must operate at a switching frequency lower than 45kHz. However, the datasheet says the minimum switching frequency is 420 Hz. Would the controller adjust the frequency itself if this situation with the minimum time happen?


texts: Voltage monitor circuit (reverse polarity protection with high voltage cut-off)

texts:
I want to make a circuit which performs these tasks:

1) Protect the load against reverse polarity.

2) Protect the load against over voltage.

Load = Raspberry pi

Reason for this circuit - Pi is not directly being powered through the USB jack. There will be a DC jack where the users are supposed to plug in a 5V 2A power supply with circular pin. Ultimately this will be given to the micro-USB jack. This is being done because Pi is inside a casing and it's not possible to expose the micro-USB port directly.

I have come up with this circuit:

How I think it works:

Mosfet will prevent turn ON in case of reverse polarity.

If polarity is correct, mosfet will turn ON. I have set up a voltage reference to output 5.6 VDC. A comparator will compare this to DCOUT. If DCOUT > 5.6 VDC, OPAMP will generate a HIGH turning the mosfet OFF.

Am I correct?

Possible concern - When OPAMP turns off the mosfet, the entire circuit will lose power and mosfet will turn ON again. I will get a oscillating voltage on DCOUT equal to 5.6 VDC. Am I right?

Should I put another mosfet downstream which will cut off in case of DCOUT > 5.6 VDC? If it's downstream, I can make sure that there is no oscillations. Example:

Is there a better alternative to all this?


texts:
First off:

This is for a one-off (or two-off) hobby project, nothing more serious. If this were a commercial design, I would go 4-layer at once (though I wouldn't be designing such a project in the first place).
Going 4-layer is acceptable only if TRULY necessary; such boards cost at least twice as much in these quantities, and the 2-layer PCB still costs more than the components combined.
The goal is to pass the USB 2.0 signal, mostly unharmed, between two connectors (USB-B to USB-A, both female), nothing more; my PCB does not actually use the signal.

(If these points moves the post into "too narrow" territory, feel free to ignore them :-)

So, the question is: is this possible, with acceptable results? The main goal is, of course, to allow High-Speed (480 Mbit/s) communications.

According to the USB specification, the differential pair should have a differential impedance of 90 ohm, and a to-ground characteristic impedance of 30 ohm. However, USB appears to tolerate a fair bit of abuse; an SMSC app note (PDF) where they discuss 2-layer USB 2.0 PCB layout mentions that the single-ended impedance isn't as critical as the differential, and that a "45 to 80 ohm" range is acceptable.

The board specs are 1 oz copper, with 63 mil FR-4 in between.
According to a few impedance calculators, such as this one (which, unless I misunderstand something, doesn't display the single-ended impedance as well), it appears that 50 mil traces with 10 mil spacing gives ~90 ohm differential and ~80 ohm Z0.
(Those values are from the Saturn PCB Toolkit calculator which is free, but requires download.)

The traces would be on the order of 3 inches long, and likely go in an upside-down U shape to go near the board edges, so that I have space to route everything else (sub-MHz signals only) without breaking the ground plane under the USB traces.

I do of course realize that the entire endeavor is a bit insane; however, again, it's for a hobby board, and it appears to have been done by serious companies as well.
High-speed is really still a bit beyond me, but the rest of the project is simple; I just need to get this signal across the PCB and everything else is a piece of cake.

If you missed it, the main question is: is this possible, with acceptable results?
If there are better 2-layer routing methods (for example, this short article uses coplanar waveguide routing for this purpose), please do tell. I can't find much information (that is both detailed and understandable, but with no details or equation/calculator mentions) about this at all.


texts: Using TIMER 1 without enabling interrupt in C on dsPIC33E

texts:
I am trying to decipher a C code in which Timer1 is being used for measuring the period of a digital signal, using dsPIC33EP256MC506. The timer interrupt is not being enabled, and there is no interrupt service routine for this timer. I'll post only the relevant portions of the code, since the actual code is Huge! The program is just initializing the timer as follows in the main() routine:

    volatile unsigned int ContinueTimeStep __attribute__ ((near)) = 0;
    int main() {
          PR1 = 0xFFFF;        /* Period */
          T1CON = 0x8030;      /* enable timer, 1:256 input clock prescaler */
     /* Main Loop */
      for (;;) {
        while (!ContinueTimeStep) ;
        asm("BCLR.b _ContinueTimeStep,#0");/* ContinueTimeStep--; */
        MyFunction();
      }                                    /* End for(;;) */
    }

In MyFunction() nothing is being done with the timer. The timer reading is only utilized in period calculation on rising edge. This done inside the change-notification ISR as follows:

void __attribute__((__interrupt__,__auto_psv__)) _CNInterrupt(void)
{
      /* Change Notification on Port F0*/
      if (portF_Xor & 1) {
        if (portF_Copy & 1)                /* rising edge detection*/
        {
          CN80_RisingPeriode = Timer1 - TimerCN80_Old;
          TimerCN80_Old = Timer1;
          CN80_ChangeDetectedFlag++;
        }

        TimerCN80_Old = Timer1;
        }
}

As I mentioned, I looked around in the code, but could not find a Timer 1 ISR. So I am pretty sure there isn't one. My question is, is this even valid? Will the timer automatically overflow and start from zero, once the period is reached? What happens if the interrupt occurs right after the timer 1 has overflown? The period will be calculated as negative? Thank you for your valuable input!


texts: How to calculate the values of \$R\$ and \$C\$?

texts:
Greetings, it is asked given the next circuit

so that it can be calculated the values of the components \$R_1\$, \$R_2\$ and \$C\$.
Ok, Im given the next data and question (besides the values !):

\$iR_1(0^+)=20mA\$ ;
\$V_C(\infty)=76.73V\$ ;
\$PR_2(\infty)=588.8mW\$;
\$V(t)=94u_1(t)V\$ (94*unit step volts)

This says the problem, I'm writing down if this helps, don't pretend to have a question of questions. =)

How much time does it take to \$R_1\$ to reach \$6.64mA\$?
Make a graph for \$V_C(t)\$ if \$V(t)=10δ(t)\$.

Lets says the most interesting part to me is calculating the values of the elements, so the first thing done its to get the mathematical model of the system, taking the variable of \$V_C%\$, it yields as

\$V(t)=CR_1\displaystyle\frac{dV_C}{dt}+\displaystyle\frac{R_1+R_2}{R_2}V_C\$

and rewriting
\$\displaystyle\frac{V(t)}{CR_1}=\displaystyle\frac{dV_C}{dt}+\displaystyle\frac{R_1+R_2}{CR_1R_2}V_C\$

Neat!

Next to obtain the total response of the system using the Laplace transform yields:

\$V(t)=\displaystyle\frac{94R_2}{R_1+R_2}-\displaystyle\frac{-94R_2}{R_1+R_2}e^{-\displaystyle\frac{R_1R_2}{CR_1R_2}(t)}\$

and the impulse response

\$h(t)=\displaystyle\frac{94R_1R_2^2}{C(R_1^2R_2+R_1R_2^2)}e^{-\displaystyle\frac{R_1R_2}{CR_1R_2}(t)}\$

But after that, I have no right idea what to do, so taking the \$V_C\$ value as steady state then \$V_C=VR_2\$ and \$V_R1=V(t)-V_C=94-76.73=17.27V\$ and from the step response taking the permanent part can it say that

\$\displaystyle\frac{94}{R_1}=76.73\$ then \$R_1=1.225Ω\$
;  to know \$IR_2\$ it is used the power form of \$P=IV\$ then \$IR_2=\displaystyle\frac{588.8mW}{76.73V}=0.007673A\$

and \$R_2=\displaystyle\frac{76.73V}{0.007673A}=10000Ω\$

But then I dont get how to get the C value.

What am I missing?

Update: Step response
- \$\displaystyle\frac{V(t)}{CR_1}=\displaystyle\frac{dV_C}{dt}+\displaystyle\frac{R_1+R_2}{CR_1R_2}V_C\$ ;

aplying the Laplace transform to the equation and the input:
- \$\displaystyle\frac{94}{SCR_1}=SV_C(S)-V_C(0)+\displaystyle\frac{R_1+R_2}{CR_1R_2}V_C(S)\$ ;
grouping:
\$\displaystyle\frac{\frac{94}{CR_1}}{S(S+\frac{R_1+R_2}{CR_1R_2})}=V_C(S)\$ ;
Using partial fractions
\$\frac{94}{CR_1}=\frac{A}{S}+\frac{B}{S+\frac{R_1+R_2}{CR_1R2}}\$ ;
\$A=\frac{R_2}{R_1+R_2}\$ and \$B=\frac{-R_2}{R_1+R_2}\$

giving the finally
$$v_c(t)=\frac{94R_2}{R_1+R_2}-\frac{94R_2}{R_1+R_2}e^{-\frac{R_1+R_2}{CR_1R_2}t} $$
OK! im refreshing the values!


texts: DC/DC step-down regulator destruction because of inductive load?

texts:
I was evaluating PAM2316 DC/DC step-down converter and destroyed several of them, I suppose the cause could be an inductive load.

See my schematic and my layout here:

Let me explain: The circuit was working properly, clean output voltage even with maximum load of 2A. Trouble starts after testing an inductive load. Without the Schottky diode the regulator failed very soon. First inductive load was very small (Test 2), it was approx 1m wire of NiCr resistance wire. Second test (Test 1) was an heavy inductor with very low DC resistance what should cause an over current event and turning off the regulator. But the regulator didn't shut down even after current reaches 3A or so (which was the case bevore with a short circuit with a short wire) (PAM2316 is rated for 2A).

The board was a self etched double sided (with ground plane) FR4 PCB. It was cleaned properly afterwards especially the feedback specific area. [Fyi: I'm experienced in creation of self etched boards].

What do you think could be the cause for that failure? Is the circuit save with that Schottky diode now? I suppose it was caused by back emf event which causes SW pin voltages became < -0.3V. This should be avoided with the Schottky diode (200mV voltage drop). I've seen similar circuits where an Schottky diode was used in same way even in synchronous step-down converters (with top/bottom MOSFETs).


texts:
I have a gas sensor module here, with a power led and a digital out led (which glows in case of successful gas detection) built in it....
A simple circuit here, just connected the vcc and ground of sensor to a 9V battery! thats it!

The power LED glows correctly, and the digital out LED glows correctly in case of gas detection.

But the sensor module is slowly shutting down, the power LED is getting dimmer and dimmer.

I just connected a battery! thats it! 9V battery!

Is my sensor damaged? If not how to correctly use it?

I brought exactly this sensor from amazon :
MQ2 Gas Sensor


texts: Returning to PIC programming after a decade...hitting a brick wall

texts:
I used to do quite a bit of PIC programming in the mid 2000's, but haven't done anything in more than a decade.

So I bought a PicKit-4 and several 16F88 chips for a project. I managed to get MPLAB and the XC8 compiler up and running, and I've been able to download the finished code to the chip. I've verified the code is actually on the chip by downloading the memory and comparing the HEX file.

I found this 16F88-specific tutorial which is about as simple as it gets:
https://theembeddedlab.com/tutorials/pic-microcontroller-led_blink/

My code is verbatim to the code presented there. I have 5V connected to VDD, VSS to ground, and have tried using pins from both ports to no avail. It just does nothing.

I have 3 16F88 chips and I've tried 2 of them so far...don't want to try the 3rd until I'm sure I'm not somehow screwing it up. But both chips still accept programming and verify correctly.

Any ideas where I might be going wrong?


texts: AVR Programming : Chip Enable Program Error

texts:
I am working on avr controllers for a while, but I have problem with "progisp" avr programming software. When I buy a new micro-controller like atmega32 it can be programmed properly for a while but after some days, suddenly when I want to reprogram it, Progisp shows the error "Chip Enable Program Error". I use USB programmer. For better understanding here is an image of progisp software.

I have searched the internet a lot to find a solution but there wasn't a proper and useful solution for my problem. I am sure that my micro-controllers are fine and not damaged because they work as they programmed but I am unable to reprogram them.
I really thank you if you have any solution to help me.

And here is schematic diagram and real picture of my USB programmer.


texts: Why the voltage of supply got stuck when connected with leds?

texts:
I was working with some smd LED's trying to make their V-I curve. For that purpose, I connected two segments parallel to each other each containing two leds as shown, to a regulated dc power supply directly.

The voltage from supply was increased gradually.LEDs started o glow as voltage reached around 4.8V with 0.07mA current in the circuit. As I increased the voltage, LEDs became brighter as expected. But after around 7.6 V, I wasn't able to increase the voltage any further. Current reading at this point was 189.8mA. The supply is capable to provide upto 30V, 2A. Why the voltage got stuck at 7.6V?


texts: How are the circuits and design considerations for opamps and comparators different, at an integrated transistor level?

texts:
I've designed various transconductance and operational amplifiers in CMOS technologies in the past. I've also worked with clocked latching comparators. However, I've yet to design an asynchronous comparator, and its internal design seems strongly similar to an op-amp.

Suppose I wanted to design a comparator with a fully driven output (not an open drain). How would the design of my comparator and the factors I take into consideration differ, at an integrated transistor level, from a one- or two-stage opamp optimized for linear negative-feedback operation? Changes in topologies, biasing, sizing strategy?

To start off, I would suppose that you'd want a different second stage topology capable of high slew rate rail-to-rail output (and disregard its small-signal operation)... perhaps also node charge/capacitance considerations for fast recovery of the first stage from saturation?

Please note that my interest is at a transistor circuit level for integrated technologies, not at a board level. I am aware of question 90657, which covers this at an abstract/black-box level, and did not find any questions that cover this topic at an IC level.


texts: Operating an adjustable voltage regulator below minimum Vout-Vin

texts: I used an LM350 adjustable voltage regulator https://www.onsemi.com/pub/Collateral/LM350-D.PDF and to keep the wattage dissipated by the device to a minimum I have opted to make the output voltage 24VDC. Max current drawn is around 500mA. The input voltage can vary from 19VDC to 32VDC but will be 24VDC under normal conditions (24V Vehicle Supply). When the input to the circuit "Vin" is below 25.1VDC the regulator Input-Output differential will be too small and the regulator will not regulate the voltage. I cannot find any information if this will have any negative consequences eg increased noise or limiting of current flow? The circuit is intended only to limit the voltage when it goes above the normal 24V and some noise filtering as a by-product. Is there any reason not to use the regulator in the "non-regulating" / "drop-out" state most of the time?


texts: what is the voltage direction and current direction of LVDS signal at particular time?

texts:
What is the voltage and current direction LVDS signal (how it is related) ?
i.e at a time (t1) there is only one current direction and one voltage ( D+ or D-)


texts:
I am designing a PMOS current mirror in 350nm Cadence technology [attached].
Problem: keeping the dimension (W/L ratio) of both the PMOS transistors constant, I should get mirrored current the same as the reference current (according to mirror circuit principle). But I am not getting the same current as reference current. e.g.

When my reference current is 10uA then the mirror current is 16.6uA with 5V supply voltage (Vdd)

When I change the supply voltage then the mirror current started getting better as e.g.

Reference current 10uA then the mirror current is 13.4uA with 3.3V supply voltage (Vdd).

Reference current 10uA then the mirror current is 10.3uA with 1.8V supply voltage (Vdd).

Dimension of MPO: W/L=10u/0.5u
Dimension of MP1: W/L=10u/0.5u

I would like to know How and Why my mirror current is changing with changing supply voltage (Vdd)?
Thanks


texts:
On some PCB designs, specific traces are routed in curious ways. This probably has to do with high frequency design considerations and general signal behavior that I am not familiar with.

Let's take this PCB (somewhere from the web) as an example. It shows part of a PCIe card with SATA routing and DDR2 RAM:

I highlighted 4 areas that qualify as unusual trace layout (from my perspective).

What are those shapes supposed to achieve? How do designers come up with what pattern is required?
Another example of wave shaped, antenna like routing.
This is fairly rare. But obviously the designer deliberately avoided 45° traces. Why?
Curves again and a single "pulse" within the trace. How can this have any significant effect?

So what are the use cases and benefits of this techniques?

I want to be able to take those into consideration when doing future PCB designs.


texts: Is there a type of Switch that is open until Armed?

texts:
I'm designing a circuit that will need to be off until the user decides to 'arm' the circuit. It should then always be closed (and hard to hack into the on position).

Does a certain component exist for something like this purpose?

If not can you suggest a strategy?


texts:
I need help on a project I am working on.
We are trying to integrate a reaction torque sensor and I am having a hard time deciding how to go about it.
Previously I assumed that like my load cell I would be able to use the HX711 module to connect my torque sensor to my Arduino. The torque sensors use a Wheatstone bridge configuration, which is great for this module.
The problem I ran into is that the TRT-25 torque sensor requires an excitation voltage of 10V and my Arduino is only supplying 5V. When I tried powering my sensor separately with 10V I quickly found out that these HX711 modules are not designed to handle 10V.
Needless to say that I am now wondering how I should power my sensor, but also which A/D converter can be used to get this working.
The same manufacturer sells all the components to get this working, but it is hundreds of dollars more and our budget doesn't allow for it.
I am posting links here so you can see the sensor. What I am considering now is finding a 10V source and connecting the signal pins to my analog pins on my Arduino. I am hoping based on the raw value I can compute a torque measurement based upon this small piece of information their tech support gave me. (X mv/v * EXCITATION v = TORQUE in/lbs).
FYI, I don't have much more information outside of what is on the site for the sensor. My project uses a small enclosure and I have an Arduino proto shield to power my other 3 sensors. I am limited on space but could probably incorporate a small power supply and replace the current HX711 module.
https://www.transducertechniques.com/trt-torque-sensor.aspx


texts: What are 9 degrees of freedom in robotics?

texts:
I found on SparkFun a module which detects movement in 9 degrees of freedom (DOF). I'm only aware of 6 DOF: translation in X, Y, Z direction, and rotation about X, Y and Z axis. What are the other three?

edit
I'm aware that there are robots with more than 6 DOF, but in these each segment has only 6 DOF maximum. The human hand (including wrist) has 23 DOF.


texts: AVR ADC performance: interrupts vs. manual conversion

texts:
I have a device on ATMega16 microcontroller that is supposed to constantly send ADC measurement results over USART. The controller is operating at 16MHz with an external crystal and ADC prescaler is set to 128. I have tried two methods of performing ADC conversion and sending the results.

The first method is based on interrupts

    int main(void) {
        ...
        while (true) {}
    }

    ISR(ADC_vect) {
        USARTSendByte(ADCL);
        USARTSendByte(ADCH);
        ADCSRA |= 1 << ADSC;
    }

The second method is based on manually starting the conversion

    int main(void) {
        ...
        // main loop
        while (true) {
            if (adcEnabled) {
                ADMUX |= channel;
                ADCSRA |= (1 << ADSC);
                while (!(ADCSRA & (1 << ADIF))) {
                    // Do nothing
                }
                ADCSRA |= (1 << ADIF); // Clear ADIF
                USARTSendByte(ADCL);
                USARTSendByte(ADCH);
            }
        }
    }

I've performed a number of tests which consisted of sending 32 blocks of 512 bytes (16384 bytes in total) over USART and measuring transmission time. In the first case (interrupts) the average time was 1623.13ms. The smallest result was 1535ms and the largest - 1712ms. In the second case the result was 1600.38ms which is  22.75ms less than in previous case, with a smallest result of 1530ms and the largest result of 1679ms.

So the question is: will interrupts actually decrease ADC performance and why is that happening or the results of my tests were inconclusive?


texts:
I built this circuit at home to for science (I explicitly drew the body diodes for clarity).

simulate this circuit – Schematic created using CircuitLab

Imagine the following scenario:

At time t0, SW1 is closed, thus driving both NMOS's gates to 5V (turning on the MOSFETS), and SW2 is connected to 5V.  Capacitor C1 charges over time to ~5V.

At time t1, C1 is fully charged, and SW1 opens.  Sufficient time is given s.t. the gate voltage on the NMOS goes to 0V.

At time t2, SW2 is connected to GND, while having SW1 still open.

Intuitively, at time t2, I would expect very little current (i.e. < 1uA) to leave the capacitor since it is effectively disconnected from GND.

However, when I measure the voltage drop across C1, I see a significant and rapid drop (down to about 2.5V), in about 0.5 second.

Why is this?  According to the datasheet for the BUK553 MOSFET, the Zero gate voltage drain current should be at most 10uA at room temperature.


texts:
I have a DAC that I am trying to design a circuit with. The goal of the circuit is to check whether the DAC is working or not, plain and simple.

The DAC in question is the PMI PM-7545 12-bit DAC. A link to the datasheet is below:

http://robot-and-machines-design.com/Files/Datasheets/Analog%20Devices%20Inc/PM7545GP.pdf

I can power the chip, but I'm not sure how to set up a simple circuit to check whether it is working or not. All of the tests that I read about seem to use something like a Raspberry Pi to drive the 12 inputs and read the output on a multimeter, but I don't have anything like the Pi that can drive each of the 12 inputs. What kind of simple circuit is recommended to check whether a DAC is working or not?

The datasheet of the 7545 contains a diagram of a burn-in circuit. I never heard of this term before, but from what I researched, a burn-in circuit is used to test the operation of the circuit under long periods of time to ensure functionality over time before the device fails. Looking at it, I'm unsure whether it would ensure that it is working, since the outputs are driven to ground, and the inputs are driven to high-rated voltage.

EDIT: Thanks to Glenn W9IQ for his answer. Below is my proposed testing schematic:

simulate this circuit – Schematic created using CircuitLab

The inputs would vary depending on what I'm trying to get at the output, so depending on the bits, they would be at ground or 5 volts, and the switch would just be a wire that I would short to GND to enable it.


texts: Is the footprint or ball/land pattern for DDR1/2/3/4 IC's a standard?

texts:
I have looked across a few DDR3 IC's from different companies and different densities with the same data bus width, and they all seem to have the same packages (dimensions, ball pitch, etc) including what balls correspond to what function (excluding the top address bits for different densities).

Is this because there is a (convention?, JEDEC?) standard for what package and pads are used for various densities/bus widths of DDRn memory? I am asking because I am wondering if I can design a footprint for a project of mine that I can assume will work when populated with different (timing and density) DDR3 IC's assuming the following:

Data bus width is the same.
All the necessary address lines are connected.
I have the ability to configure the DRAM controller.
Routing can handle the potentially faster speeds of a different IC.


texts:
When reading the Platinum Resistance Thermometer Manual, I was faced with this unknown IC (see pp. 38 from the manual):

I searched the web with the following keywords: SON044 and 1020B-44, but didn't get any meaningful results back.

I think it should be a kind of FPGA.

What is it? Would anyone please introduce it to me?


texts: Design methodology - Single-Phase vs Three-Phase Inverter

texts:
I simulated a small DC Microgrid in Matlab/Simulink. In order to connect the DC bus of the microgrid to the AC grid, I used a three-phase - two-level inverter.

I have done some research and I found out that for an application like mine (a small power application) it's better to use one phase inverter.

So, in Simulink its pretty easy to convert a three-phase inverter to one phase but I would like to ask if the parameters (modulation index, the switching frequency, the dc link capacitor size e.t.c. ) that I used in the three-phase inverter, can be used for the one phase inverter. In other words, if I use the same parameters for the one phase inverter, my system will work properly?


texts:
Was planning to work on some long distance communications with RS485 / RS422 and I saw one of these boards on Aliexpress,Amazon etc..
Does anyone know what all those passive components could be?
Would love if anyone has seen a schematic of any of these boards any reference schematic for the same.

Cheers and TIA


texts: Is it Ok to add heat sink on top of an RF chip?

texts: The chip that I want to attach a heat sink is a WiFi chip Ralink RT3070 and its separate RF amp chip YP243433 both have 85C Tjunc. The amp chip barely gets hot. The main chip gets hot but still can be touched (maybe 50-55C). Will the RF performance affected by heat sink? There's no RF can/lid/shield on both chip.


texts: Schmitt Trigger configuration for enabling power from guitar pickup

texts:
I would like to enable power to a regulator from a 1Vpp guitar pickup. Threshold can be between 0.2V and 1V. And I need it to disable after about 60 seconds of no signal from the pickups.

I'm considering using a Schmitt trigger and a RC circuit add the delay for disabling the regulator. I need to increase RC to get 60 seconds and change the schmitt trigger specs from my schematic.

Does anyone know of a better way to accomplish this?

Update (from Andy's comment)


texts:
I was measuring a device that isn't working with an continuity meter. I've identified this socket as the problem.

It sits between the batteries and the rest of the device, I guess for loading the batteries. The positive red wire runs right through but the negative black one is soldered at two points (A and C in the picture).
Now if I measure at point B, which is the negative contact of the socket, I get connection to both A and C. But if I measure between A an C directly, there is no connection.
How can this be?


texts: Ga has three valence electron, and As has five valence electron. How do they share electrons so that each has 8 valence electrons? Does each Ga atom share 5 electrons with 5 different As atoms?


texts: Help identifying components on Sony PS Vita 2000 motherboard

texts: I need help identifying 2 components from a Sony PS Vita 2000 motherboard. One is a chip with code AG8 only (has 5 pins each side). The other one is like a 4 pin resistor. No resistance between 2 pins and high resistance to the other 2.


texts: Why can capacitor act as voltage source and inductor as current source?don't explain this with a math formula,just use an easier method,thanks a lot!


texts:
I Designed a 5v,7A power supply from 24v input for my new project. It is giving 4.9v, but have noise issue. When I increasing the load its noise level is also increasing.

I connected 1A load and a rapberry pi at the output. Is it an acceptable level of noise.

I am attaching the schematics and output waveform, Kindly check it and suggest me a solution.


texts: How to connect an LED indicator to a circuit?

texts:
I would like to know how can i add a safety switch with an LED indicator to a circuit , so that if the safety switch is on then the LED lights , and when i want to use the device , all what i have to do is to press the normally-open switch.

I have attached this schematic and im not sure if it will work correctly  ,as i am a very beginner in electronics

Thanks


texts: How do I decrease the slew rate of an op amp?

texts: I need to reduce the slew rate of a voltage follower, so that if I change the input signal from 0 to 5V, the output signal will rise progressively up to 5V in say, about 5 seconds, so a slew rate of 1V/s.


texts: How to capacity threshold dectector with a simple analogic circuit?

texts:
I try to make an extremely simple capacitive proximity sensor using a metallic plate and a plastic sheet, to show how it works. My aim is to put the capacitor in a circuit that lights a lamp (or a LED) if its capacity C is above some critical value C0 and turns it off when C is smaller than C0 (the order of magnitude of the capacities is 1-100 pF. Now the problem is to keep the circuit as simple as possible, so that it is easy to understand (and fits in what my target already knows). I especially want to avoid microcontrollers (thus an Arduino setup like in Triggering a capacitive sensor electronically? is not possible) - the most advanced device I can use is an op amp.

All I have now is a AC tension divider followed by a rectifier, but it has grown because I have to amplify the output then compare it with some reference voltage to turn on and off the lamp.

Do you have any idea ?

Thanks.


texts: Switching 100 different LM35 with one uC

texts:
I want to read the temperature of about 100 different LM35 with only one ATmega16 or ATmega32.
I want to read 8 LM35 at one time and switch to the next 8 and so on.

what kind of multiplexer or switch shall I use?

any other suggestion will be very appreciated.


texts: Repairing an SSD using a soldering iron vs oven reflow?

texts:
I'm trying to recover data from a cheap kingspec ssd that stopped working some months ago. It is not recognized by the computer at all. I get some messages saying the computer is trying to connect to the sata link (ubuntu server) but it eventually gives up.

The information is not irreplaceable so I thought I'd give it a shot at trying to repair it, just for fun. I looked up some methods online.
I first tried to "power cycle" the SSD, that didn't work.

I then tried to bake it in a small oven I have for non-food experiments, by setting the temperature to 250ºC, without preheating it. I was supposed to leave it for around 8 minutes, but since the pcb plastic started "crackling" I shut off the oven after about 6 minutes and let it cool for 20 minutes. This also didn't work.

I then tried to set the temperature to 200ºC, preheated the oven, and left it in there for around 9 minutes. Still no luck, but I can now see that one of the solders on one of the chips looks "wrong". See image below. I have a soldering iron and some decent solder with flux inside, but no standalone flux or heating gun. Should I try to use my soldering iron to set that solder or should I just try to bake it again and at what settings?

Many thanks.


texts: Why is there a resistor and a capacitor in this AUX cable's diagram?

texts:
I am looking at a BMW's 3.5mm AUX cable diagram:

The left and right wires are connected together through a resistor and there is a capacitor on each left and right audio. The third is a ground.
I have two questions,

Why is there a capacitor on each left and right?  Why do we need to store energy, is it going to delay the audio?
Why are the right and left audios connected together with a resistor? Wouldn't that make my audio mono as opposed to stereo?

P.S: More detail:
This is used to add AUX female socket to BMW Model E39/53's audio system, the X13598 will be connected to the back of the audio system and the B1 (3.5mm female aux socket), will take input from phone (or iPod) through a male AUX cable.


texts: Some GPIO Pins does not work in STM32VLDiscovery

texts:
This is my code:

#include "stm32f10x.h"
#include "core_cm3.h"
#include "custom.h"
//#include "LCD-HD44780.h"

//int i;
int main(void)
{
    RCC->APB2ENR |= BIT3;

    GPIOB->CRH   |= BIT0 || BIT1;
    GPIOB->CRH   &= ~BIT2 && ~BIT3;
    GPIOB->BSRR  |= BIT8;

    GPIOB->CRH   |= BIT4 || BIT5;
    GPIOB->CRH   &= ~BIT6 && ~BIT7;
    GPIOB->BSRR  |= BIT9;

    while (1)
    {
    }
}

custom.h file:

#include <stdint.h>
#define BIT0  (uint32_t)0x1
#define BIT1  (uint32_t)0x2
#define BIT2  (uint32_t)0x4
#define BIT3  (uint32_t)0x8
#define BIT4  (uint32_t)0x10
#define BIT5  (uint32_t)0x20
#define BIT6  (uint32_t)0x40
#define BIT7  (uint32_t)0x80
#define BIT8  (uint32_t)0x100
#define BIT9  (uint32_t)0x200
#define BIT10 (uint32_t)0x400
#define BIT11 (uint32_t)0x800
#define BIT12 (uint32_t)0x1000
#define BIT13 (uint32_t)0x2000
#define BIT14 (uint32_t)0x4000
#define BIT15 (uint32_t)0x8000
#define BIT16 (uint32_t)0x10000
#define BIT17 (uint32_t)0x20000
#define BIT18 (uint32_t)0x40000
#define BIT19 (uint32_t)0x80000
#define BIT20 (uint32_t)0x100000
#define BIT21 (uint32_t)0x200000
#define BIT22 (uint32_t)0x400000
#define BIT23 (uint32_t)0x800000
#define BIT24 (uint32_t)0x1000000
#define BIT25 (uint32_t)0x2000000
#define BIT26 (uint32_t)0x4000000
#define BIT27 (uint32_t)0x8000000
#define BIT28 (uint32_t)0x10000000
#define BIT29 (uint32_t)0x20000000
#define BIT30 (uint32_t)0x40000000
#define BIT31 (uint32_t)0x80000000

LED on Pin 8 turns on But in Pin 9 does not!. and This all of code I wrote. I cant find out where is problem.


texts: Need to transmit 3 bits through window glass continuously

texts:
I have three water level sensors that will live outdoors, and three fancy-looking indicator lights that will be inside.  I would like to continuously transmit the on/off state of the three sensors inside.  It can be through a window, so infrared seems like a possibility.  The simplest thing I can think of is for each sensor to activate an oscillator at a different frequency, sum those signals together and send them over infrared, then detect them with whatever the opposite of an oscillator is -- a bandpass filter plus something?  Like DTMF.  Does this sound like it would work?  If so, what is the name of the component that would detect oscillations in a certain band?  Are chips available with several oscillators or detectors on them?

Edits in response to comments: Both sides of the window can have continuous power from a power brick plugged into the wall.  The sensors can all be close to each other and wired to each other.  I can also send a wire right to the other side of the window glass for the IR emitter, although it would be cool if I didn't have to.  Reliability is not a huge concern, the worst that happens is that someone goes outside to water plants when they don't have to.  Relatedly, I don't care if it works in the rain, the water will always be high enough if it's raining.

Edit 2:  I guess I said "continuous" because I was thinking of an analog solution, but if the simplest answer really is some sort of packet-based thing, then I guess I don't care if it takes as much as 10 seconds to update the indicator lights.


texts: How do I create a static library for the AVR Atmega328p?

texts:
I am attempting to create a library much like the Arduino in C.

I have tried in the past and although I have lost the code, I remember simply getting loads of undefined references to functions specified in the header files and in the library which did contain all the object files (checked by avr-objdump).

I want to know how I should compile the library (example makefile) and how the program should be compiled to it. Also, do I need to re-compile the library for every AVR and Clock speed, or is there a way around it?

If you need any more information, just ask.

Thanks

EDIT: Example (not working)

program.c

#include "test.h"

int main(void)
{
    test_function();
}

test.c

#include "test.h"

void test_function()
{
    int i;
    i++;
}

test.h

#ifndef __TEST_H_
#define __TEST_H_

void test_function(void);

#endif


texts: Why can one pour water on a car battery's terminals (12 Vdc) and not have shorting

texts:
When cleaning a standard 12 Vdc car battery's terminals, it's a common practice to pour a mixture of baking soda + hot water all over the terminals.  The water can spread and effectively short out the battery in two ways:

Positive terminal to negative terminal
Positive terminal to car chassis (to negative terminal)

Why does this not cause major problems (ex: explosions)?

Background

Quora answer: What happens if a car battery short circuits?

YouTube video: Shorting Out a 12V Car Battery

Indicates that shorting a car's battery can be quite detrimental.

YouTube video: How to clean car battery terminals corrosion Cheap and EASY with baking soda Car maintenance

You can see the water connects the battery's positive terminal to the negative terminal.  In my mind, this should create a short circuit, as the water is effectively shorting the positive and negative terminals.  However, nothing bad seems to happen.  Why is this?

Research

Reddit post: ELI5: Why is it safe to pour water all over a car battery?

Says water isn't all that conductive, but I am not sure if I agree with this vague statement.


texts: Sense Automotive 12V Circuit from 3.3V microcontroller safely

texts:
I want to sense a circuit state in an Automotive circuit (12V nominal) from a 3.3V microcontroller (MSP430Gxxxx). The circuit is normally 12V (or VBat) until either the Wireless ECU or a Door Key grounds the line, triggering an event. How can I safely (in terms of not frying the MCU or affecting the state of the line) sense this?

From the Manufacturer description, this seems to be a simple Open Collector system, it is not a power circuit, so I don't know how much current can be sourced.

I would tap into junction J6.

As this is automotive, current consumption is a concern as well. My MCU will be set up to interrupt on a falling edge trigger, and asleep unless that happens.


texts:
I'm an electronics student and I have been trying to understand this FM transmitter diagram (taken from electronicshub.org) for a long time. I had put efforts to learn it by surfing the web but parts of the circuit remain totally puzzling to me. It would be really grateful if anyone could explain the diagram thoroughly and as detailed as possible from top to bottom.

I even don't understand why the capacitors C2, C4 (I thought C4 should be parallel to R5 as in voltage biasing circuits bypass capacitors are used, don't know why it is in series), C5 and C9 are used in the circuit. Some websites say the capacitor C9 is used to stabilize the LC oscillation in the tank circuit but I want to know how it does so?

And what about the C8 and L2 tank, why is another tuned oscillator added at the last? Mathematical explanations are very much welcomed.


texts:
I have a simple preamp circuit coupled with a class AB power amp. The design is quite simple and I am pretty sure I already made it work a couple of years ago.

simulate this circuit – Schematic created using CircuitLab

The power transistors are the TIP31C and TIP32C.

While the preamp works correctly, when I power the class B amp, some components burn:

TIP31 (always);
C3 (often);
C2 (always);
D1 (always);
C4 (some times);

The load is an electromagnet; the 50/-50 V supply is required for the electromagnet to work. It should consume no more than 1.5A at full duty.

I think that there is no wiring error in the circuit since a friend and I triple checked it.

Finally, the DC supplies are both independent lab supplies, floating and not connected to earth.

So, something wrong with this circuit? (obviously... ;) )

EDIT:

Here is the result of a 3s frequency analysis. I reversed the polarity of C2 and C3 and I removed L1 since Circuit Lab could not simulate with it.

What puzzles me is that the output of the preamp (blue signal) doesn't have the same amplitude than what I measured with the oscilloscope. I measured a signal with a 26-27V DC bias and a 4V bottom and 49.8V top swing (sorry, I don't have a picture right now).

I will simulate with OrCAD Pspice and see if there is another result...


texts: How can LM324 work in dual supply mode when it only has 2 pins for the supply?

texts: The LM324 quad opamp data here says that it can work in single as well as dual supply mode. However, it has pins for positive supply and another for ground on its sides. The pin for ground can also be used for negative supply as per the datasheet. However, if we shall only connect the +V and -V and no GND, how does the concept of -V arise in the operation of the op-amp?


texts: Hi, I'm fairly new to BJTs and I've been trying to analyze the above basic current mirror to prove that $$I_{ref} = I $$ (aproximately), but have gotten nowhere. I have attached where I've gotten so far


texts: Don't RF devices need to be shielded to pass FCC?

texts:
I'm looking at this device. Internally, the Bluetooth chip isn't shielded but it still seems to have passed FCC. Addition to that, there was no Modular Approval Request Letter, which typically requires one to declare that the radio elements are shielded.

So, how come this could still be approved even without an Approval Request Letter or shield?


texts:
I have a 120VAC DC motor speed controller (diagram attached as picture) it works very well, however in the circuit there is a 5000K POTENTIOMETER that controls the actual speed/voltage - The controller output range is from 0VDC to 120VDC to the brushed 1.75 HP motor. I am controlling a LATHE with this motor and circuit.

The problem is that if I rotate the pot about a quarter of the way around; the motor is already at the maximum speed I require (200RPM) or 50VDC. If I continue turning the pot the voltage could reach 110VDC and the lathe will spin over 4000 RPM and this is a nono.

I need to know how can I change the circuit (or the pot) so that the voltage output to the motor is not higher than 50VDC with a full turn of the pot.  Bigger Pot?


texts:
DSP applications for Hysterisis
How is hysteresis used for DSP?


texts: Why can't I find Phase to phase voltage like this

texts:
I know that that in 3phase ac,
Vll = sqrt(3) * Vln

I got confused about the sqrt(3) part so I draw phaser diagram and the resultant vector will give me the phase -phase voltage

But it only gives me 230V , why?
Can anyone explain how it got sqrt(3) in equation??


texts:
I need to supply power for some power diodes. The power supply units are current regulated, the diodes are connected in series.
Let's say that i hve 3 strips of leds, each one needs 400mA, around 20V +/- 2V and one power supply providing a regulated source of 1200mA max 40V.
Is it possible to make a current mirror using discrete bjts ( not IC )?
Can i expect to have mismatches (due to the BJTs tolerances ) lower than 50mA ?
How much difference between the strips crrent i should expect?

Thanks in advance.


texts: How can I change component values in a premade circuit

texts:
I do projects quite frequently, but the only problem is that sometimes I don't have the right component, and it takes to long to ship.  I heard that some people change the values of their components (i.e. resistors, capacitors, coils).  How can I do this in an example circuit.

I would really appreciate it if I could do this.


texts: How to calculate voltage regulation of three phase transformer correct in given case?

texts:
we both agreed on the value of series impedance which is (12.82[82] ) however what i think he did wrong is the value of secondary reflected on primary

since it is Y-delta
7967/480 = root(3) a  hence a will be 9.6

so the vs* = 480 * 9.6
           =4608

Is(phase) will be (200k/(3(480)) = 80,16[-25.84]
NOW vp(phase) = vs* + (Is/a) * Z(eq)
        4608+107[56.16]
        =4668[1.1]

so vp(line)=root 3 v(phase)
           8086[1.1]

Vr in my calculation (4668-4608)/4608 = 1.3 %

Is my answer correct and the solution did a mistake if so ok but if not what did I miss in my calculation?
hope that you help me with this ! :/


texts: Terminology confusion with sensitivity used with gain

texts:
Regarding force transducers like strain gauges, the resolution is the smallest change in the load that represents a change in the output values of the measured forces and moments. The smaller the resolution of a sensor, the larger is the sensitivity of the sensor.

Lets say we have a force transducer outputting 1mV/N; if then we amplify this by gain of 10 it will output 10mV/N.

Does that mean we increased/changed the "overall sensitivity"? Or the term "sensitivity" should only be used when no amplification is introduced?


texts: Why is there a lead (Pb) warning on extra heavy duty batteries?

texts:
I have some batteries labelled as Extra Heavy Duty with a picture of a trashcan and the letters Pb for lead, and an x over the trashcan which I believe means not to discard in the trash. The batteries also say not for retail sale, so I suspect that they were the original batteries in some children's toys from which I pulled them out. I found on the web that the likely chemistry is zinc chloride, and I don't see any lead in the chemical reaction.

What is the source of the lead? Is it just impurities in the zinc, as can occur with zinc-galvanized hardware? I know that in the galvanization process lead is added to the kettles for metallurgical reasons. Is there something similar going on here?

Thanks


texts:
I recently bought a cheap soldering hotter and solder iron station from E-bay. It came with lots of extras. Sadly it never came with any good tips, but it did come with these..

What are these for?

Thanks
Student


texts: How to connect a dsPic30f2010 to pickit3 icsp

texts:
I recently bought a pickit3, I have a development board for the dsPIC30f but it the pickit3 doesn't seem to be able to read the chip. When I try to connect to the chip, I have the error:

  Target Device ID (0x0) does not match expected Device ID

At first, I had an error that the pickit couldn't detect a voltage on vdd. I fixed it by either powering the dev board with an external power supply or powering the devboard using the pickit (with the advanced settings). Unfortunately, the pickit doesn't seem to be able to power the device with 5v and I have to set a voltage below 4.75v.

After that, I have the problem with the device id that can't be detected... Now, I'd like to put my pic on a breadboard with the simplest schematic to program it.

That's what I have so far:

simulate this circuit – Schematic created using CircuitLab

It's quite difficult for me to get around the datasheets of microchip. I couldn't find anywhere why a resistor and a capacitor are required on vpp.

I guess the schematic I made might be wrong as the VPP pin should be able to power up to 13v.

Also, as I never succeeded to get the pickit3 working yet, any idea how to verify if the voltage emitted from VPP is right. As I understand, in order to get the dspic in programming mode, the pickit has to provide between 12v and 13.5 volts on the vpp/mclr pin. I tried to measure VPP with my multi metter but I guess my multimetter is too slow to pick the voltage right away.

Edit:
New schematic with decoupled vss/vdd and 100ohm on vpp added.


texts:
I'm making a simple switch box and I've done quite a bit of looking but I can't find a 4 pole single throw switch anywhere on the major component seller sites in the UK (farnell.co.uk etc.), although I imagine if there is one it wouldn't be reasonably priced.

So, can anybody think of a simple and fairly cheap way I could use a single pole single throw switch to control 4 circuits, or perhaps some alternative to achieve the same goal? Ideally I would like to use a basic rocker switch, but beggars can't choosers.


texts: Analog signal --- what to do with extra/unused layer in a 4-layer PCB

texts:
My layout for an analog signal circuit uses three layers.

I have a ground plane, top layer with signal traces, and one layer with power traces --- I have +15, -15, +5, and -5;  all four voltages generated from a 5V input.

Does it make sense to split the ground plane into two separate planes, one for power (i.e., for the decoupling capacitors), and one for the components that connect the various signals to GND?

And since I only have a handful of those, I wonder whether the signals should use a star ground configuration, instead of a ground plane?

The only connections to ground for the signals come from one Sallen-Keys 2nd-order 1MHz low-pass filter (two connections, since it has some bandpass gain) and one AD8138 to produce a complementary/differential output (two connections --- one resistor that connects to GND and the Vocm input that's set to GND). Plus the grounds of the two output connectors.  So, it will be rather easy to set up the star ground layout for these, where the center point is the (only) point that connects to the other layer with the ground plane.

Does this make sense?  Please feel free to suggest any alternatives.


texts:
I am looking to integrate these sewable LED ribbons into a project.

https://www.sparkfun.com/products/14138

I am wondering how it is possible to power 50 Blue LEDS in series with only 2x 3V coincell batteries or minimum 4.5V as specified on the description.

From what I know, Blue LEDS have quite a large voltage drop. If this is added across all the LEDS in series, 6V should not be enough...I also do not have a specification on the resistors included

Can anyone explain how these work?


texts: Latching battery switch triggered by interrupts

texts:
I've got an accelerometer with a couple interrupt pins and I've figured out how to get it to fire its interrupts on any change in acceleration or lack thereof for a given duration.

What I want to do is have it switch a 3.7v battery power supply on and off based on the interrupts - if no change in acceleration for a couple of minutes, have the interrupt latch the power off to the rest of the device. And conversely, if the device is already in the powered off state, have it latch the power back on the instant you pick it up. Obviously for this to work the accelerometer always needs to be powered and can't latch power off to itself.

How can this be accomplished? Don't cringe but is there such a thing as a "toggle" transistor?


texts: Where is the text for the symbol stored in LTspice?

texts:
The following is an image of the symbol opamp.asy.

I opened the same file using Notepad++ and have pasted the contents below:
Version 4
SymbolType CELL
LINE Normal -32 32 32 64
LINE Normal -32 96 32 64
LINE Normal -32 32 -32 96
LINE Normal -28 48 -20 48
LINE Normal -28 80 -20 80
LINE Normal -24 84 -24 76
WINDOW 0 0 32 Left 0
SYMATTR Prefix X
SYMATTR Description Ideal single-pole operational amplifier. You must .lib opamp.sub
SYMATTR Value opamp
SYMATTR SpiceLine Aol=100K
SYMATTR SpiceLine2 GBW=10Meg
PIN -32 48 NONE 0
PINATTR PinName invin
PINATTR SpiceOrder 1
PIN -32 80 NONE 0
PINATTR PinName noninvin
PINATTR SpiceOrder 2
PIN 32 64 NONE 0
PINATTR PinName out
PINATTR SpiceOrder 3

I am surprised to find that the text Unnn is missing in the file. Where is this text stored? For example, if I make a symbol my_symbol.asy, and using the GUI I add some text to it reading this_is_my_symbol, then the file my_symbol.asy does contain the aforementioned string when opened in a text-editor.
Is this different for the symbols and the subcircuits shipped with LTspice? In that case where are such strings stored?


texts:
I have an Arduino ProMicro 5V 16MHz board from sparkfun.

I have a 3Cell LiPo powering the entire thing (via the relevant regulator bringing it down to 5V). This is part of a TriCopter. I tap the 12V positive pin through a voltage devider into pin A1 (if the USB is pointing up, and the pins away from you, this is the 6th pin from thje botttom right).

How do I refer to this pin in my program?
A1 is: static const uint8_t A1 = 19U. This reads 0V from my battery.

My code is as follows:

/*
 * Battery Sensor
 * Battery Voltage monitor
 */
const float ReferenceVoltage = 5;   //default reference on a 5-volt board
const float R1 = 54350;//49200;             //55K2 Ohm resister
const float R2 = 32600;//31000;             //32K6 Ohm resister
const float ResistorFactor = 1023.0*(R2/(R1+R2));
const int BatteryPin = A1;          // V(out) of Voltage devider circuit is attached to analog pin A1

/// <summary>
/// Reads the current Battery voltage
/// </sumary>
void ReadBatteryVoltage()
{
    int Value = analogRead(BatteryPin); //read the value from the Analog Pin
    //Serial.println(Value);
    float BatteryVoltage = (Value/ResistorFactor)*ReferenceVoltage; //Calculate the ratio
}

I know this is an electronics forum and I'm asking a programming question, but this is electronics. I would apreciate any pointers. This is driving me mad.

update:
Thanks to PeterJ for helping me confirm what I knew about which Pin to read from and also for the improved syntax. The problem was however in line 8 below:

1: /// <summary>
2: /// Reads the current Battery voltage
3: /// </sumary>
4: void ReadBatteryVoltage()
5: {
6:  int Value = analogRead(BATTERY_PIN);    //read the value from the Analog Pin
7:  //Serial.println(Value);
8:  BatteryVoltage = (Value/ResistorFactor)*ReferenceVoltage;   //Calculate the ratio
9: }

That local variable was the one getting populated with the Battery voltage being read from the BATTERY_PIN leaving the similarly named global variable, elsewhere in my application at it's default state of 0.0;

I just removed the type declaration which made it use the global variable as it should and all worked fine.

This is the type of thing that drive programmers crazy.
Hardware is hard...pfff! hardware is hard because most hardware now requires software. ;-)... which of-course is created badly by wetware.


texts: Boom stand or articulating clamp trinocular microscope?

texts:
What's the downside for each? Is the boom stand more steady, but takes up more desk space?
I'm debating between the two, but I can't seen to find any info on the pros/cons of each type.


texts: A series \$\text{R}\$ and \$\text{C}\$ circuit

texts:
I've a series R and C circuit, with a DC voltage source. I want to find the charging function of the capacitor. My question is: is the method I use right?

My work (using Laplace transform):

$$
\begin{cases}
\text{U}_{\text{in}}(t)=\text{U}_{\text{C}}(t)+\text{U}_{\text{R}}(t)\\
\\
\text{U}_{\text{R}}(t)=\text{I}_{\text{R}}(t)\cdot\text{R}\\
\\
\text{I}_{\text{C}}(t)=\text{U}_{\text{C}}'(t)\cdot\text{C}\\
\\
\text{I}_{\text{in}}(t)=\text{I}_{\text{C}}(t)=\text{I}_{\text{R}}(t)
\end{cases}\space\space\space\space\space\space\Longrightarrow^{\mathcal{L}}\space\space\space\space\space\space
\begin{cases}
\text{U}_{\text{in}}(\text{s})=\text{U}_{\text{C}}(\text{s})+\text{U}_{\text{R}}(\text{s})\\
\\
\text{U}_{\text{R}}(\text{s})=\text{I}_{\text{R}}(\text{s})\cdot\text{R}\\
\\
\text{I}_{\text{C}}(\text{s})=\text{C}\cdot\text{s}\cdot\text{U}_{\text{C}}(\text{s})-\text{C}\cdot\text{U}_{\text{C}}(0)\\
\\
\text{I}_{\text{in}}(\text{s})=\text{I}_{\text{C}}(\text{s})=\text{I}_{\text{R}}(\text{s})
\end{cases}
$$

So, we get:

$$\text{U}_{\text{in}}(\text{s})=\frac{\text{I}_{\text{in}}(\text{s})+\text{C}\cdot\text{U}_{\text{C}}(0)}{\text{C}\cdot\text{s}}+\text{I}_{\text{in}}(\text{s})\cdot\text{R}\Longleftrightarrow\text{I}_{\text{in}}(\text{s})=\frac{\text{U}_{\text{in}}(\text{s})-\frac{\text{U}_{\text{C}}(0)}{\text{s}}}{\text{R}+\frac{1}{\text{C}\cdot\text{s}}}$$

So, when I want to find U_c(s):

$$\text{I}_{\text{in}}(t)=\text{U}_{\text{C}}'(t)\cdot\text{C}\space\space\space\space\space\space\Longrightarrow^{\mathcal{L}}\space\space\space\space\space\space\frac{\text{U}_{\text{in}}(\text{s})-\frac{\text{U}_{\text{C}}(0)}{\text{s}}}{\text{R}+\frac{1}{\text{C}\cdot\text{s}}}=\text{C}\cdot\text{s}\cdot\text{U}_{\text{C}}(\text{s})-\text{C}\cdot\text{U}_{\text{C}}(0)$$

Solving U_c(s), gives me:

$$\text{U}_{\text{C}}(\text{s})=\frac{\frac{\text{U}_{\text{in}}(\text{s})-\frac{\text{U}_{\text{C}}(0)}{\text{s}}}{\text{R}+\frac{1}{\text{C}\cdot\text{s}}}+\text{C}\cdot\text{U}_{\text{C}}(0)}{\text{C}\cdot\text{s}}$$

Knowing that the voltage source is DC:

$$\text{U}_{\text{in}}(\text{s})=\frac{\text{U}_{\text{in}}}{\text{s}}$$

So:

$$\color{red}{\text{U}_{\text{C}}(\text{s})=\frac{\frac{\frac{\text{U}_{\text{in}}}{\text{s}}-\frac{\text{U}_{\text{C}}(0)}{\text{s}}}{\text{R}+\frac{1}{\text{C}\cdot\text{s}}}+\text{C}\cdot\text{U}_{\text{C}}(0)}{\text{C}\cdot\text{s}}=\frac{\frac{\text{U}_{\text{in}}-\text{U}_{\text{C}}(0)}{\text{R}\cdot\text{s}+\frac{1}{\text{C}}}+\text{C}\cdot\text{U}_{\text{C}}(0)}{\text{C}\cdot\text{s}}}$$

Using inverse Laplace transform, I found:

$$\text{U}_{\text{C}}(t)=\text{U}_{\text{in}}+e^{-\frac{t}{\text{CR}}}\left(\text{U}_{\text{C}}(0)-\text{U}_{\text{in}}\right)$$


texts: What is a single-flash transistor-and-capacitor circuit actually called?

texts:
The internet is awash with diagrams where two lights alternately flash with the aid of transistors and capacitors. However, I remember at school being shown an introductory circuit in which one light lit up for a while and then went out as the second one switched on, to remain on permanently.
Despite searching for terms such as 'single flash circuit' or 'most basic transistor circuits', I have not been able to find the circuit diagram for it.
Can anyone tell me what this circuit is called? I remember it being an incredibly basic one, but the details I have long since forgotten.


texts: What is the purpose of this thing on NiMH rechargeable batteries ? Can't figure out what this component is or its purpose

texts:
What is the purpose of this thing on NiMH rechargeable batteries? I can't figure out what this component is or what it is for.
I'm trying to change the batteries in a Hoover automated vacuum cleaner.
I want to know if it is necessary to have these on the new set of rechargeable NiMh batteries.


texts: Stable LDO voltage when Vin goes down momentarily

texts:
I have an application where Vin comes from a battery pack (3V - 7V) but on occasion and under heavy load, Vin drops to just above 2V for ~ 1 seconds before recovering.

There is a 3.3V LDO that provides power to the microcontroller. The LDO uses a pass transistor to regulate the voltage, and due to the body diode, current can travel from output to input when Vout > Vin + 0.2

To prevent the microcontroller from resetting, my intent was to add a capacitor large enough to keep the microcontroller alive until the battery voltage recovered.

However the body diode would conduct at a certain point, and the energy that would have gone to the microcontroller, would now be going to the LDO as well. I am not sure how much energy would  be lost here.

This both an energy and cost sensitive project.

What can possible by done other than throwing a diode at the output of the LDO (Would like to minimize that energy loss) ?


texts: What does the subthreshold swing of a mosfet actually mean?

texts:
I have found several interpretations of the sub threshold swing.One is " The subthreshold swing of a device is defined as the change in gate voltage which must be applied in order to create a one decade increase in the output current ".
The other one is that the amount of gate voltage that is needed to bring down the sub threshold current by one decade . which of them is correct and in which context.
Are these two interpretations same but for the former case  device is in strong inversion and the latter case the device is in weak inversion ?
What i understood is to have large change in the output current low gate voltage should be enough which implies sub threshold swing should be smaller.If this is true then how are tunneling FETs better over the conventional MOSFETs.(where in tunneling FETs we say the sub threhold swing is not limited?)


texts: Bandpass filter for summing amplifier input

texts:
I need to create a bandpass filter for a single input to a summing amplifier. In this example of a summing amplifier, I understand how the capacitor and resistor in series creates the low cutoff frequency of \$1/(2\pi RC)\$ for the individual signal. But what is the best way to create an upper cutoff frequency for an individual signal here?

I know a capacitor in parallel with the feedback resistor like this would create an upper cutoff frequency, but that would affect all input signals:

What's the best solution to this?


texts: State Space Averaging combined with Static Analysis

texts:
In class we learned about State Space Averaging Mathod to analize DC-DC converter topologies.
Therefore we defined a stete vector x containing variables proportinal to the stored energy in a circuit element. Voltage for capacitors and current for inductors.
With a system like x' = Ax + Bu we calculate the small-signal behaviour. The Output of the system was described in the form y = Cx + Du.
With the matrices C and D one can decide how the output of the system is described.
However I'have the problem that I would like to know every current and volatge in my system. For that the output vector y is to small (in my view) because it's holding only variables for C and L and not for resiors, diodes and so on.
In the first semesters a learned about static resistor circut analysis with a system like a = Bx where we have a vector for current, one for voltage and a matrix for the resistances.
Now my Question:
Is there a common way to describe the entire circuit as matrix, derive the matrices A, B, C, D from the whole circuit matrix, calculate a state and plug y back in the whole system matrix to get every voltage and current for a given state?
I know it should be possible because I did this many timed by hand with a system of equations. But, is there a common way how to do it? And if there is, could you recommend some papers or literatimure.


texts:
I have Nexys2 Spartan 3E board and I am running Ken Chapman's UART IP core, I need to transmit data to another device at a baude rate of 460800. I was successful in sending data at 115200 and 9600 using 50MHz clock of my board, but when it comes to 460800 I get garbage values. I even tried with 100MHz clock (using DCM) but it did not really work.

Any ideas why I am having these issues?


texts: Is there any reason that any speaker connected to any computer couldn't be used for listening/surveillance?

texts:
I understand that it's possible to use the headphone port of a laptop as a microphone, but what are the physical limitations to using any speaker in the same way?

I'm curious about what makes amplification a one way street and if it is necessarily always the case.


texts: Implementing nrf51822 timer example mbed

texts:
I am using the PCA10001 eval board and I have been able to get things up and running using the mbed platform but now I am implementing a timer based interrupt for that I was using a ticker. But detaching and reattaching the ticker results in the ticker not working properly. My time for calling the interrupt is 1ms.

Facing issues with the ticker I want to use the nrf51 timer1 or 2. I ran the example code here https://github.com/NordicSemiconductor/nrf51-TIMER-examples/blob/master/timer_example_timer_mode/main.c

with a few modifications

#include "mbed.h"

DigitalOut myled(LED1);
RawSerial pc(USBTX, USBRX);

void start_timer(void)
{
  NRF_TIMER2->MODE = TIMER_MODE_MODE_Timer;  // Set the timer in Counter Mode
  NRF_TIMER2->TASKS_CLEAR = 1;               // clear the task first to be usable for later
    NRF_TIMER2->PRESCALER = 6;                             //Set prescaler. Higher number gives slower timer. Prescaler = 0 gives 16MHz timer
    NRF_TIMER2->BITMODE = TIMER_BITMODE_BITMODE_16Bit;       //Set counter to 16 bit resolution
    NRF_TIMER2->CC[0] = 25000;                             //Set value for TIMER2 compare register 0
    NRF_TIMER2->CC[1] = 5;                                 //Set value for TIMER2 compare register 1

  // Enable interrupt on Timer 2, both for CC[0] and CC[1] compare match events
    NRF_TIMER2->INTENSET = (TIMER_INTENSET_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos) | (TIMER_INTENSET_COMPARE1_Enabled << TIMER_INTENSET_COMPARE1_Pos);

  NVIC_EnableIRQ(TIMER2_IRQn);

  NRF_TIMER2->TASKS_START = 1;               // Start TIMER2
}

/** TIMTER2 peripheral interrupt handler. This interrupt handler is called whenever there it a TIMER2 interrupt
 */
void TIMER2_IRQHandler(void)
{
    if ((NRF_TIMER2->EVENTS_COMPARE[0] != 0) && ((NRF_TIMER2->INTENSET & TIMER_INTENSET_COMPARE0_Msk) != 0))
  {
        NRF_TIMER2->EVENTS_COMPARE[0] = 0;           //Clear compare register 0 event
        myled=1;         //Set LED
  }

    if ((NRF_TIMER2->EVENTS_COMPARE[1] != 0) && ((NRF_TIMER2->INTENSET & TIMER_INTENSET_COMPARE1_Msk) != 0))
  {
        NRF_TIMER2->EVENTS_COMPARE[1] = 0;           //Clear compare register 1 event
        myled=0;      //Clear LED
  }
}

int main(void)
{
      pc.baud(9600);

    start_timer();                              //Configure and start timer

    while(true)
    {
//              pc.printf("%i\n",1);

//         Enter System ON sleep mode
        __WFE();
        // Make sure any pending events are cleared
        __SEV();
        __WFE();

//         For more information on the WFE - SEV - WFE sequence, please refer to the following Devzone article:
         //https://devzone.nordicsemi.com/index.php/how-do-you-put-the-nrf51822-chip-to-sleep#reply-1589
    }
}

It compiles with no errors but nothing happens. Any ideas on what I could be doing wrong.

I have tried using both updated and old mbed libraries.


texts: What could cause a sawtooth waveform to have these gaps in between?

texts:
I'm having problems with these gaps in between the sawtooth waveforms produced by a free-running bootstrap ramp generator triggered by a schmitt trigger. Why are they occurring and how could I fix this?

At first I thought it was because of the pnp transistor, but now I'm not so sure.

I tried to redesign my circuit multiple times, but I still get the same problem. What could I be doing wrong? Or where should I look?

This is the circuit producing that:


texts: My 3D printer has a 240W power supply that takes 220V AC as input and gives 12VDC/20A as output. I'd like to use a relay, controlled by a raspberry, to turn the printer ON/OFF. My question is: should I put the relay between the 220V and the power supply, or after the 12V? What are there pro and cons between the two configurations?


texts:
After reading   about some of the photodiode characteristics on the internet  I got really confused with the photodiode working principle. I tried to search for them in google , got some definitions , but it still confuses me a lot.

I found a topic on the internet which indicated that "photodiode is in reversed biased while LED is in forward biased" ?

So , is the reversed bias here photoconductive mode of photodiode ?

A problem that came to my mind is that , in the figure above , do i connect the longer lead of photodiode to ground or to the negative node of op-Amp ?

And does the current direction through photodiode is opposite to its indication in any mode (photoconductive or voltanic), for example like in picture above (photodiode "points up" while current goes from negative node to ground )?

Update 1 : thanks to excellent guys , i now understand a little more. But what i confused is the concept about the photoconductive mode . Is that true that any photodiode with voltage accross it different to 0 ( disequal 0) is in photoconductive mode ?
Another question is that : if the photodiode is in photoconductive mode , if i change the polarity (example : anode initally connected to ground , now i changed : kathode to ground) , does the mode (photoconductive / photovoltaic) change too?


texts:
Can two devices powered by two different power sources (laptop's USB and house plug + transformer) communicate through GPIO without share GND?

If the GND isn't the same for the transformer and the laptop, the voltage gap can be huge. Such a gap can destroy or damage both devices, laptop and the transformer.

Is it safe to do this communication or should I add some optocouplers for galvanic isolation?

I mesure the voltage difference between the two grouds with a multimeter : few mV. Will the gap change over time?


texts: Problem powering ESP8266 with two 1.5V AA cells

texts:
I was testing the deep sleep mode featured in the ESP8266.

I have a simple USB battery power supply associated with a 3.3V power regulator (https://www.adafruit.com/product/2165).

Everything is fine, I have a low current in the deep sleep mode.

Then I tried to power the thing with two 1.5V AA cells and eveything got messed up: my ESP keep restarting (led blinking). I both tried the ESP-01 and Huzzah from Adafruit.

I noticed two things:

(1) Input voltage drops at 2.8V when ESP is on.

(2) Input current raises over 130mA (compared to 70mA with the USB battery).

My conclusion would be that the voltage being too low, the chip trie desperately to power up at full throttle, .. and fails then reboots.

Am I right?

Edit: ESP8266 seems to be able to work ender 3.3V : http://www.esp8266.com/viewtopic.php?p=23790#p23790

What is the solution?

Thanks to you.


texts: Clock switching hangs when switching back to original source

texts:
I am currently working on a project where the clock needs switching between the Primary Oscillator with PLL (POSCPLL) to the FRC and back again.

I have initialised the Clock as the PRIPLL by using the config bits:

#pragma config FNOSC = PRIPLL
#pragma config POSCMOD = HS
#pragma config FPLLMUL = MUL_20
#pragma config FPLLIDIV = DIV_2
#pragma config FPLLODIV = DIV_1
#pragma config FPBDIV = DIV_1
#pragma config FCKSM = CSECME

which sets the OSCCON to 0x01453360 and gives an 80MHz clock signal. I then use this function to switch to the FRC:

INTDisableInterrupts();
//Execute the System unlock sequence
SYSKEY = 0xAA996655;
SYSKEY = 0x556699AA;

OSCCONbits.NOSC = 000;
OSCConfig(OSC_FRC, 0, 0, OSC_FRC_POST_1);
mOSCSetPBDIV(OSC_PB_DIV_1);
//Initiate the clock switch
OSCCONbits.OSWEN = 1;
//Lock SYSKEY
SYSKEY = 0x33333333;
int k = 0;
//Wait until OSWEN = 0 and switch is complete
while (OSCCONbits.OSWEN == 1){
    k++;
}
//Re-enable interrupts
INTEnableInterrupts();
SYSTEMConfig(GetStandbySystemClock(), SYS_CFG_ALL);

To switch back to the POSC PLL i use the same structure but change the value of NOSC to 011; and update the OSCConfig to

OSCConfig(OSC_POSC_PLL, OSC_PLL_MULT_20, OSC_PLL_POST_1, 0);

Which matches the sequence in the pragma config bits. However, when i run it on the PIC32MX, the debugger on a PICKIT3 cannot get past the function with these set-up bits, however it will allow for it to be set at half the speed (OSC_PLL_POST_2).

If the debugger is paused however, it can be seen that the OSCCON is the same, but when it is resumed, the software restarts.

If anyone could tell me if i have missed a setup bit to enable to switch back to the initial clock or if there is a better way to do this i would be extremely grateful!

Extra information:
PIC32MX775F256L,
Custom board,
8MHz Crystal (FOXSDLF/080-20),
The crystal is connect to the OSC1 and OSC2 (pin 63 and pin 64),
loading capacitors 22pF

Thanks in advance

EDIT
I have now also tried setting the new clock source without using the OSCConfig function and using the hard values instead.

OSCCONbits.NOSC = 0b011;
OSCCONbits.PLLODIV = 0b000;
OSCCONbits.PLLMULT = 0b101;
OSCCONbits.PBDIV = 0b00;

When PLLODIV is 0b000 the same thing happens, However, when it is set to 0b001 it works and the system is half speed, as it is divided by two

EDIT 2

I have now tried to switch between clocks without using the #pragma config bits
I have removed

#pragma config FPLLMUL = MUL_20
#pragma config FPLLODIV = DIV_1
#pragma config FNOSC = PRIPLL
#pragma config FPBDIV = DIV_1

I use the same functions to set up the clock in the first place, and get the desired outcome no problem. I then switch to the FRC clock, again no problems. Only when i try to switch back to the original clock do i encounter a problem. It is also not helped if i switch to the same clock with different parameters first before switching back to the correct ones via the FRC again. But it will work if i switch to the clock with different parameters first, then switch to the correct one via the FRC on start up.

I now have the code isolated to avoid any other code affecting the clock switching and still no difference.


texts: Is it possible to create AC with just battery, transistor and coils?

texts: I set a circuit that shows how the electromagnetic induction works. But as what i studied in  physics class, there will be alternating current but there's nothing that seems to create an AC! All electric components that i used was coil, breadboard, transistor, resistance, battery and LED. The picture and circuit map is like this


texts: Is there anyway one can toggle a light using a program on a computer?

texts:
I am a bit new to electronics, but I am a programmer.
The thing is that I want to control one or two lights using my code on my computer
Arduino and similar devices are not an option in the meanwhile. I don't either have an RS232 port.
Note that I can extract IC and stuff from things like JoySticks or whatever if needed.
Some things I know/learned:

Turning on/off a light is basically [not] passing positive voltage to the LED, where the LED is always connected to an appropriate ground
Turning on/off a light is a logical operation, so if we are using an analog jack (or whatever), we need to convert it to a logical output, since we need the light either on or off, not something in between
Using ports like USB requires a microcontroller chip

Note that I don't mind doing hacky stuff, I'm doing that being a hobbyist, not for production


texts: In a half-wave uncontrolled rectifier with RL load why does the voltage spike when current reaches 0A?

texts: I understand that the inductor creates a negative voltage to oppose the change in current but I don't understand why the voltage spikes up instantly when the current reaches 0A.


texts: Why does reversing the oscilloscope probes cause ringing in the signal?

texts:
I am measuring a PWM signal in an oscilloscope using probes with a 1X and 10X switch (active?).

I'm measuring across a resistor which is in series with an LED which is driven by an NPN 2N3904 transistor. The signal is about 2.3V.

One way around (with the ground croc clip attached to the higher voltage side and the probe hook/clamp on the lower voltage side) I get a clean PWM signal. The other way around though I get distinct ringing on the 0V portion of the PWM signal.

The frequency is about 47kHz. This happens when I measure other parts of the circuit e.g. across the LED and the effect is far stronger, almost completely obscuring the signal.

Why would the oscilloscope have this effect and how can I avoid it?


texts:
i've been looking at ESP32-GATEWAY from Olimex (Schematic here), i've seen that in order to power on/off the LAN8720 chip, they use a P-Channel Mosfet (WPM2015) and a Pre-Biased transistor (DTC114YKA), this configuration is a little bit unclear to me, i don't understand three main things:

Why use a transistor to control the mosfet?
How it generally works this configuration?
Why they added the 10k-22uF capacitor from ground to source of the mosfet?

A partial screen of the interested circuit portion is below:


texts: Is my calculation for stepper motor peak current correct?

texts:
I'm planning on using an RS PRO 892-8732 bipolar stepper motor for a project and was following an online guide to familiarize myself with stepper motors. As the motor is bipolar, I'm also going to need a use a driver, specifically this one.
The driver I'm using has the following formula on the data sheet for it's maximum current:
ITripMAX = Vref / ( 8 × Rs)

The motor has a rated current of 1.68A (I'm assuming this is the peak current as the motor doesn't list a peak current on the data sheet), and the driver has an Rs of 0.11 ohms. This means I should set Vref to 1.4784 (rounding it down to 1.45 or lower as potentiometers aren't exact and I don't want to exceed the rated current).
I just want to sanity check this calculation with someone who might be more experienced with stepper motors.


texts: Why residual current device doesn't trip

texts: I bought a residual current device to my home workshop for safety and I was testing it .I connected it to workshop's power cable and for test I used 4.7k ohm resistor .device rated for 30mA (220v) and I connect to resistor between live wire and ground .It tripped as soon as I connect it , no problem in here .Then I add 14V transformer to the plug and this time I used 220 ohm resistor but nothing happened .I used my multimeter for current values and even I remove the resistor between live and ground no current flow.Why the transformer changes how the ground work ?


texts: I have an audio circuit im building from schematics. . The schematic calls for 30nF, 220nF, 6.8nF, 22nF, 5nF, and 2.2nF capacitors ...all of which I cannot find to order. . I even converted these values into microfarads and picofarads and can't locate these parts either. . Can I substitute a closer more common value capacitor for each of these?  I can send you the schematic if it helps answer my question


texts: Ground Earth Resistance explained in electrical system

texts:
I have several questions about the electrical systems used in the field and the grounding mechanisms.
So, as far as I understand there are multiple systems that can be used to distribute electrical current in the field: TT, TNS, TN-C, TN-C-S. In a single phase system it will be the live wire, ground and the protective ground (aka PE).
The TNS, TN-C and TN-C-S systems are relatively easy to understand, there is a clear path through wires for all of the signals (live, ground and PE), but for the TT system the PE will be connected separately using the grounding/bonding/earting (see last question) rod buried in the soil. And the current is supposed to flow through the ground back to the transformer in case of a ground fault. But here is my first question: How is this useful, the soil has a big resistance/impedance and that means it will cause a really small current to flow through it and maybe the breaker won't break. Also it is somehow confusing because searching the web, the actual resistance needs to be smaller then 200 ohm (TT system), maybe there is something that I don't understand, but having the transformer 100 meters away with a soil resistivity of 40 ohm*m (got it from random table found online for the best conductor soil) will give you at least 40 * 100 ohm (clearly bigger then 200?). Still looking on some YouTube videos some guys are measuring the Earth Ground Resistance and it's about 2.1 ohm ? Video for loop impedance.
The second question is about the Earth Clamp Resistance Meters. How are those doing their job ? As far as I understand they will induce a current in the loop and measure the current and using the Ohm law will deduce the resistance. But how is the loop formed, through the ground back to the transformer and then through the ground back to the device ? Can't really see the loop here.
And the last question is about the terms used, I need some explanation for the actual meaning, because when searching the web, people tend to interchange them whenever they want in a wrong way.
Grounding vs earthing vs bonding
PS:
English is not my primary language.
There is a very high chance that I've got everything wrong.
These questions have haunted me for a long time, any online resources to further understand are highly appreciated.


texts: Building Temperature Control for Cotton Candy Machine

texts:
I want to build a temperature controller for a cotton candy machine. The model I have is: Carnival King Cotton Candy Machine

I was thinking about building a PID control circuit with an SSR but realized it many be difficult to mount a thermocouple on the rotating heating element. What is the best way to go about building one. Any advice woul dbe greatly appreciated!


texts: Verilog: Slow Clock Geneator Module (1Hz from 50Mhz)

texts:
I wrote clock generator module, i dont know if it is true but the problem is in my reg module. The error is:

ERROR:HDLCompilers:246 - "UpDownCounter.v" line 74 Reference to scalar reg 'clk_1Hz' is not a legal net lvalue

ERROR:HDLCompilers:102 - "UpDownCounter.v" line 74 Connection to output port 'clk_1Hz' must be a net lvalue

1 HZ CLOCK GENERATOR

module slowClock(clk, reset, clk_1Hz);
input clk, reset;
output clk_1Hz;

reg clk_1Hz = 1'b0;
reg [27:0] counter;

always@(posedge reset or posedge clk)
begin
    if (reset == 1'b1)
        begin
            clk_1Hz <= 0;
            counter <= 0;
        end
    else
        begin
            counter <= counter + 1;
            if ( counter == 25_000_000)
                begin
                    counter <= 0;
                    clk_1Hz <= ~clk_1Hz;
                end
        end
end
endmodule

And here my Reg 4 bit module

module Reg4(I, Q, clk, reset);
input clk, reset;
input [3:0] I;
output [3:0] Q;
reg [3:0] Q;

reg clk_1Hz = 1'b0;
slowClock clock_generator(clk, reset, clk_1Hz);

always@(posedge clk_1Hz) begin
    if (reset == 1)
        Q <= 4'b0000;
    else
        Q <= I;

end
endmodule

Can u see my problem ? :(


texts: What is needed to convert 2 DisplayPort lanes into 4?

texts:
Essentially, I'm trying to connect a source with only two HBR2 lanes to a device that requires four HBR1 lanes. Theoretically, the bandwidth is there. But what kind of an IC would I need to accomplish this?

Redrivers seem to only refresh the signal, they won't convert it.

Demuxers simply act as relay switches; they don't actually touch the signal itself.

It seems like most DP to DP++ converter ICs (where the intention is to support HDMI or DVI output) will only act as a redriver when outputting via DP, so that doesn't really help me, either.

All I've found is this converter, which might be what I'm looking for, but I can't really figure out if it will actually convert from two to four lanes, or will just refresh the signal. It's also BGA, and I would much rather prefer a QFP or QFN.

To give a little more insight into the use case: I've got an eDP source with two eDP 1.2-compliant lanes that support up to HBR2, and I'm trying to connect it to a 2560x1440 (@60Hz) eDP panel that requires 4-lane HBR1. I've already tried connecting with just two HBR2 lanes and it didn't establish a connection; I'm not entirely sure if the DP spec requires the implementation of lane reduction the way PCI-E does, or if my panel just doesn't support eDP 1.2, but either way it isn't working.


texts: How do you restart the MSP430 Launchpad programmatically with Energia?

texts: Can anybody tell me what Energia method I can call to programatically reset the MSP430 Launchpad.  Under certain circumstances, I need it to power down and back up again.  It needs to shut down power to its I2C devices when it resets itself.


texts: In which stage is decided the Sigma-delta ADC resolution (number of bits) after conversion? Modulation stage or decimation stage?


texts:
Currently I'm using an IR LED connected directly to a PCB where an Arduino UNO is connected. When I send a command with the Arduino, the LED sends what I want to an IR receiver.

Now I'm thinking to change a bit this solution, because I want to extend the IR emitter, but not with some loose wires, I want to use a jack 3.5 cable.

Can I just use a mono cable, connecting the two wires to the PCB, and at the other end connect the male plug to a female 3.5 mono plug, where the LED will be soldered? I don't need to have much power because the emitter and the receiver will be very close to each other.

So, my ultimate doubt is if it'll work with a mono cable or do I need a stereo one?


texts: Why 180 degrees of phase margin should be considered?

texts:
We've had one feedback on the phase difference, with the gain as 1. At 300 to 60 degrees, there's just a phase difference, and 61 to 299 degrees, the output is larger. Shouldn't we consider an angle other than 180 degrees? Why does the actual control not affect the output?

enter image description here


texts:
I have made a circuit that is meant to control 12V LED Strips using a WS2803 Chip.
The problem I am having is that the L7805CV regulator reaches 80°C while the 1k resistor bank reaches 40-50°C.

Because of the nature of the WS2803 chip being a current sink this is the only combination of parts I could find that would work to switch LED Strips.

The circuit: each channel has a 1k pull up that has a transistor connected to it, that transistor feeds a 390ohm pullup that goes to a final transistor that works with the LED Strips. All pullups go to a 5V line provided by the regulator from 12V.


texts: Voltage gradient in voltage difference across a resistor

texts:
If I have a voltage difference V from terminal 1 to terminal 2 of a resistor.
I take an arbitrary point P along the resistor, between terminal 1 and terminal 2, and take terminal 1 as a voltage reference.
Does the voltage difference between the point P and terminal 1 increases from 0 at terminal 1 to V at terminal 2 ?
Is there a voltage gradient across a resistor ?

The question is about circuit theory in general.