texts:
Background
I was considering making a temperature sensor from some NPN transistors. I read the Wikipedia page on Silicon Bandgap Temperature Sensors (can't use more than 2 links...) and this piece from Analog Devices, Inc., which I think neatly explains how two or more transistors can be used to sense temperature. Yet another reference is
The basic idea is that the base-emitter voltage V_BE can be related to temperature via.
V_BE = kT/q ln(I_C/I_s)
So, for two transistors.
V_BE1 = kT/q ln(I_C1/I_s1)
V_BE2 = kT/q ln(I_C2/I_s2)
For two matched transistors, as in on an integrated circuit, I should have I_s = I_s1 = I_s2. Further, if I take the difference of these two.
V_BE1 - V_BE2 = kT/q ln(I_C1/I_s) - kT/q ln(I_C2/I_s)
Applying the fact that the difference between two logarithms ln(x) - ln(y) = ln(x/y),
V_BE1 - V_BE2 = kT/q ln( [I_C1/I_s] / [I_C2/I_s] )
And this equals
V_BE1 - V_BE2 = kT/q ln( [I_C1] / [I_C2] )
So, the difference in base-emitter voltages will give me temperature multiplied by a constant.
V_BE1 - V_BE2 = [k/q ln(I_C1/I_C2)] T
I made the following circuit. Since VB1 = VB2, VBE1 - VBE2 should equal VE1 - VE2, I measured the voltages VE1 and VBE2.
Schematic

simulate this circuit – Schematic created using CircuitLab
Data
Now, with CH1 across RE1 and CH2 across RE2, my oscilloscope reads the following.
I also used the oscilloscope's MEASURE utility to find that VE1 was about 1.88 volts on average and VE2 was about 1.76 volts on average. I also measured this with my digital multimeter and found that the voltages fluctuate, but at one time I measured 1.909 volts across VE1 and 1.782 volts across VE2. The actual resistance values of RE1 and RE2 are 98.4 kiloohms and 1.01 kiloohm respectively.
So I_C1 = VE1/RE1 and I_C2 = VE2/RE2.
Problem
Now, if I go strictly by the equation
V_BE1 - V_BE2 = [k/q ln(I_C1/I_C2)] T
with k as Boltzmann's constant, q is the elementary charge (charge of an electron), and I_C1 and I_C2 are the collector currents of transistor 1 and 2 respectively, I should get a temperature reading for T.
T = (V_BE1 - V_BE2) * 1/[k/q ln(I_C1/I_C2)]
I get absurd temperature readings like -5415.135909660602 degrees Celsius or if I flip the values for I_C1 and I_C2, I get 5415.135909660602 degrees Celsius.
Is there something I'm missing? Thanks!


texts:
So after the channel is pinched off in a MOSFET the equation that relates current and voltage through the MOSFET changes. What I am confused about though, is why in the derivation of this new formula the voltage is integrated from V = 0v to V = Vgs - Vt where Vgs is the potential difference between the source and the gate and Vt is the threshold voltage (at least that's what I think that's what those represent).

Anyway here is an visual representation of the circuit mentioned:

Here is also the integral I mentioned (equation 6.16):


texts: heat dissipation in watts of equipment in a box

texts:
Here is the situation, some electrical equipment will be in low ambient temperatures and I need to make it warmer so that there is no damage to it.
I want to calculate how much power in watts is needed to heat up equipment inside a box made of aluminum.

The box is 5 inches X 5 inches X 11.5 inches (surface area is then 1.727 ft^2) it is made of aluminum and it is .1 inches thick and insulated.

from previous tests I recorded that when the ambient temperature was at -20 Celsius for a long time (at least 1hr) the surface temperature of equipment was steady at -10 Celsius and the air between the box and equipment was -11 Celsius.

Two questions:
1) How much power in watts is being dissipated by the electronics?
2) How much power in watts is needed to bring the temperature of the surface of equipment to 0 degrees Celsius? to 10 C?

I did some research and found this:  http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatcond.html

heat conduction formula

Q/t = kA(Thot - Tcold)/d

where k = thermal conductivity,
A = surface area,
Thot - Tcold = 10,
d = thickness,

The issue with this is that when I plug in k for aluminum = 205 or .5 by adjusting the units in the formula I get a large value for Watts either way...
am I doing this completely wrong is there another formula that would better model this problem?


texts: EXTI code on STM32F4 doesn't work properly

texts:
I've been learning to program in bare-metal and I'm trying to learn how EXTIs work. I wrote a simple program that would turn on an onboard LED on PB7 when triggered by a button on PC13. Code as follows:
Initialization:
  RCC->AHB1ENR |= RCC_AHB1ENR_GPIOBEN | RCC_AHB1ENR_GPIOCEN;
  RCC->APB2ENR |= RCC_APB2ENR_SYSCFGEN;

  GPIOB->MODER |= GPIO_MODER_MODER0_0 | GPIO_MODER_MODER7_0 | GPIO_MODER_MODER14_0;

  GPIOC->PUPDR |= GPIO_PUPDR_PUPD13_1;

  SYSCFG->EXTICR[4] |= SYSCFG_EXTICR4_EXTI13_PC;
  EXTI->IMR |= EXTI_IMR_IM13;
  EXTI->RTSR |= EXTI_RTSR_TR13;
  EXTI->FTSR &= ~EXTI_FTSR_TR13;

  NVIC_EnableIRQ(EXTI15_10_IRQn);

Interrupt Handler:
void EXTI15_10_IRQHandler(void)
{
    if (EXTI->PR & EXTI_PR_PR13)
    {
        GPIOB->BSRR |= GPIO_BSRR_BS7;
        HAL_Delay(1000);
        GPIOB->BSRR |= GPIO_BSRR_BR7;
    }

    EXTI->PR |= EXTI_PR_PR13;
}

When running this program, the LED turns on and stays on. When checking the SYSCFG_EXTICR4 register, bit 5 which corresponds to Port C seems to be set to zero even though I enabled it in the code (Although I think it could have something to do with them displaying the bits).

But so far, I've followed the exact instructions in the datasheet and can't figure out where I'm going wrong. Also, I'm using a Nucleo F413ZH 144 pin board and STM32CubeIDE. Thanks!
Update: SYSCFG_EXTICR4_EXTI13_PC is mapped to SYSCFG->EXTICR[3]. Also, EXTI->PR = EXTI_PR_PR13;


texts: Running traces underneath SMT components

texts: While designing PCBs, is running traces underneath SMT components considered a bad practice? And if so, what are the reasons?


texts: How can I simulate the circuit with floating node in Orcad simulation?

texts:
I simulated to test 4n25 optocoupler.
6 pin in 4n25 is base of output transistor.
According to google, 6 pin can be not connect pin (NC) because input LED
generate the base signal.

Orcad simulation alerts the 6 pin don't remain as floating node,
but I want to place this pin as floating node.

Are there any other solution to do this?


texts:
Many DB9 symbols have 2 additional pins other than the 9 signal and GND pins that they are known for. How and to what are these 2 pins connected ? Pins 10 and 11.

Is it connected to chassis ground or is it an NC just to provide more stability for the mechanical and vibration protection?


texts:
I have a microcontroller (ATmega328) that runs on 5V and another chip (MAX31855), connected via SPI as a slave (that only using the MISO line), that runs on 3.3V.

Do I need to convert the output of the slave from 3.3V to 5V?
The chip select pin (active low) is held high via a pullup resistor connected to 3.3V. Is this a problem since it is also connected to the 5V uC? I assume so, yes? Would I need to use a logic level converter for that as well?


texts: Photodiode -- photoconductive (reverse bias) vs photovoltaic (zero-bias) for tachometer

texts:
I'm building a tachometer for speeds 0 to 3600 rpm (various speed motors turning things down to whirligigs blown by the kids.).  I've got a photo diode running in photovoltaic mode generating about 50 mv pulses.  (Of course, this is a function of distance and illumination; my hand held sensor is 3 or 4 inches away from the rotating object.)

Somewhere I got the notion that running in photoconductive (reverse bias) mode would get a better signal from the diode, but my cursory research suggest that generating a current mode signal wouldn't give any different results from a voltage mode signal, as far as the quality and strength of the signal feeding into the amplifier.

In other words, photo-conductive mode wouldn't have any amplification effect relative to photo-voltaic mode.

Am I missing something?  Can you think of any reason to prefer one mode over the other?


texts: Matlab Components needed for Electrical Engineering Students

texts:
I am installing Matlab, and now I need to select the components that are required for electrical engineering projects, circuits, ect. ( for undergraduate students, not professionals)
the list is attached, please let me know which ones to select, I don't want to select them all because I know I don't need them all and also they will slow down my laptop's speed for sure.


texts: Confusion with output impedance of non-inverting and inverting opamp circuit

texts:
I'm trying to understand why the output impedance of non-inverting and inverting opamp circuit is almost zero. I found the following text on the derivation:

β is the closed loop gain above. But I couldn't understand their derivation here. Is there an easier or clearer way to reach this solution? I would be glad to see a more verbal and clearer explanation.

Edit:

If this equivalent circuit below is correct, how can we proceed from this equivalent circuit and conclude Zout of this inverting opamp circuit is almost zero? Or should I say Zout = Rout. (Rout is the opamp's internal output resistance, Zout is the circuit's output impedance/resistance)


texts: ATmega fuses for external crystal oscillators greater then 8 MHz

texts:
Currently I am trying to figure out what the correct fuse settings for my ATmega8 are, when I want to use an external crystal oscillator with a frequency greater then 8 MHz.

I have found the following table in the Atmel ATmega8 datasheet (p. 27):

CKOPT has to be programmed (set to 0). But what about CKSEL3..1?

For a 16 MHz oscillator I would probably set them to 111, because it is the highest possible value (compared with 8 MHz, if CKOPT is unprogrammed (set to 1) ).

How would you choose CKSEL3..1 for example a 10 MHz, 12 Mhz or 14 Mhz oscillator?

Simply comparing with the ranges as depicted for CKOPT = 1 seems wierd. (my calculation: e.g.: (.4/8*16)MHz=.8MHz, etc.):

CKSEL3..1 = 101 for .8 - 1.8 MHz
CKSEL3..1 = 110 for 1.8 - 6 MHz
CKSEL3..1 = 111 for 6 - 16 MHz

So do I always choose 111? If I should, in which case would the others be more appropriate?


texts: electric bedroom heated mattress vs danger

texts:
We have one 220v electric bedroom heated mattress which repaired by ordinary repairman and changed its board, the circuit is this kind:

And the burned spot in the Blanket:

Its used some resistor and one TRIAC IC ( BT139 600E), so in new circuit there is no damage on it, and the new circuit worked for almost one week usage!

Update:

I have seen some heater blanket circuit like this:

and seen in the failed circuit there is no bridge diode, also it is strange for me to use non isolated power supply in the original circuit of our blanket( dose it standard?!!!), and bypassed the bridge diodes like this kind:

And thought dose it could be the failure reason and how the heater elements could work with 0 -220v voltage ?!

So why this happened?

Thanks.


texts: Suitable resistance values for an analog IC

texts:
I was reading a chapter of the book "Continuous-Time Active Filter Design" about analog filters design. Let's consider the following band - pass filter, in which its inductances may be simulated with some GIC (Generalized Impedance Converter) circuits:

The book says that this circuit is impractical because of the presence of 0.6 Ohm resistors, which are too low. Now my question is: which are suitable values for an IC?

I have always read that the main problem is to get high resistors (since it would mean long conductive paths to get them, and so large occupied silicon area). But which is the problem of getting 0.6Ohm resistors? If it is a problem, why should not be a problem realizing the short circuit interconnections of components?

Here the internal structure of the GIC:


texts: Which infrared bulb should I use with a photodiode?

texts:
I'm currently using a photodiode (found here) along with the appropriate emitter to send data between mobile robots. I'd like to the sensor to optionally be used as an ambient light sensor using a filter with lower sensitivity.

My trouble is picking out what this "ambient light" should be. Since the photodiode is only sensitive between 750 and 1150 nm, I imagine I need an IR bulb. However, every IR bulb I look at doesn't seem to specify what wavelengths it outputs. They also seem to all be used as heat sources, which I'm not sure I need. Ideally I'd like a cheap option that I could just stick in a lamp, but I'm open to other ideas. Does anyone know where to buy the correct IR bulb? Or what the correct IR bulb would be?

Thanks!


texts: The voltage becomes zero when the load is connected

texts:
This is my circuit.
When I connect the load of 10 Ohm, the voltage goes to zero!
The voltage goes to zero even if I put resistor of 10 kOhm.


texts: Cutting the earbuds and keep the microphone: will it work?

texts:
I have old still functioning earphones with a microphone incorporated.
I want to keep the microphone and remove the earbud so that I can then put the microphone inside a small pipe and record sounds.
 I wonder if just cutting the wires powering the earbud will do the job (see picture below, scissors to indicate where I intend to cut). I am worried that this way the microphone will not work (i.e.light brown wire seems connected to black microphone wire through the mystery button).

(I am not an expert in electrical engineer at all, so sorry if my question seems too trivial to you)


texts: Help Troubleshooting Relay for Vehicle Offroad Lights

texts:
I am wiring up 2x 55W Halogen lights and 2x 100W Halogen lights on my '01 Subaru Outback. I want all 4 lights to come on when I turn the switch on. I created the wiring diagram which I followed during the install (see attached pic) but ran into an issue:

As the system stands (following the diagram), with the engine off, only the middle two, 100W lights turn on.

I measured voltage at one of the 55W lights with the switch turned on, and measured only 0.5 VDC (working 100W lights had 11.8 VDC), which means that my understanding of how the relay works is flawed. It seems that I cannot use the circuit across the relay coil to power the smaller 55W lights. The 85-86 circuit is used for activating the relay, and cannot be used for other lights.

I noticed that adding a wire to connect the wires coming from relay terminals 87 and 85 produces the desired result (all lights come on), but those wires quickly get hot and the relay starts buzzing after about 1 minute of the lights being on. By my calculations, this would result in 310W/12V = 26A through the circuit, which is a lot for the smaller 14 AWG wires. I would have expected the 20A fuse to blow, but it did not. The relay is a 30A relay and neither the 15A nor the 20A fuses blew, so I do not think the relay was drawing too much current... any idea what was causing the buzzing?

In summary:

Why can I not use the relay (as drawn) to also drive the smaller 55W lights?
What could be making the relay buzz when a wire is added between terminals 87 and 85?
What can I change in my current setup to turn on all 4 lights without stressing circuit components?

Thanks all!


texts: Is it possible to build a simple circuit where one switch controls all bulbs but small switches control individual bulbs?

texts:
Putting aside the embarrassment of asking for a 'simple' solution, I will state in advance that I know I could do this with push-to-make switches and MOSFETs. What I am stuck on is whether I am missing an obvious wiring solution that would have the same effect without parts I don't have currently.

So here's the situation:

I have three LEDs (B1, B2, and B3) in parallel in a circuit powered by a battery. Currently, one switch (S1) turns them all on, and the same switch (S1) turns them all off.

I would like more control over this system, such that B2 has a switch (S2) which ONLY turns B2 on and off, and B3 has a switch (S3) that ONLY turns B3 on and off. So far so simple. The challenge:

I would like S1 to retain the same amount of control that it currently has. So if S1 is on, B1+B2+B3 are on (regardless of the state of S2 and S3), and if S1 is off AND S2 or S3 are on, ONLY B2 or B3 (respectively) are on (in an ideal world, if S2 were already on, S1 were switched on then off, all bulbs would turn off, however I believe this is a logical impossibility)?

I have latching switches, diodes, and wires galore, but no transistors to make this. Is it possible?


texts: Convert Current source to Voltage source in Laplace domain

texts:
Is it possible, once I've converted the circuit diagram into its Laplace equivalent, to replace a current source which is in parallel with, in this case, a resistor and inductor by the usual V=IR method considering I treat the R in the equation as a combination of the impedances from both the resistor and the inductor?

Here is an example circuit for what I mean:

Here is what I've converted it to. Is this correct / allowed?


texts:
I've been trying to build an op amp circuit that takes an analog signal from my electric guitar of around -1.5 to 1.5 V to a voltage level of 0 to 5 V, so that I can put it into the ADC of a microcontroller. I used this resource to make my design specifically figure 3. I'm having trouble finding the voltage I need to power my op amps. I tried 0V and 5V and the signal is squashed and doesn't change at all. When I connect the VCC+ and VCC- to 5V and -5V, I'm getting a signal, but its centered around -1Vs. I'm using uA741 op amps.

Vref = 5V
R1 = 1 kohm
R2 = 470 ohm
Rg = 14.7 kohm
Rf = 10 kohm


texts: I have 200 mm long, 0.3 mm diameter nichrome wire. I am heating this wire with 5V AC power supply and current approximately 1.4 A. I need to calculate the exact temperature of the nichrome wire?


texts: Anyone know what kind of connector is this?The female connector size is around 18x7 millimeters


texts: Problem with connecting Nano v3 to Sharp Proximity Sensor

texts:
I am trying to connect a Sharp Analog IR Distance Sensor GP2Y0E02A to a nano v3. It accepts 2.7 - 3.3 v so I have it connected to 3.3 v from the arduino but I dont get serial output, just complete blank. When I change the code to something a little similar (see code under buggy code below) I get voltage values. So I think the problem might be with the code which I am using to convert voltage to cm below.

Buggy Code (voltage to cm)

/***************************************************************
  Arduino GP2Y0E02B example code
  Gets range from GP2Y0E02B and prints it to the serial monitor.

  By James Henderson 2014
***************************************************************/

#include <Wire.h>

int distance = 0;                // Stores the calculated distance
byte high, low = 0;              // High and low byte of distance
int shift = 0;                   // Value in shift bit register

#define ADDRESS       0x80 >> 1  // Arduino uses 7 bit addressing so we shift address right one bit
#define DISTANCE_REG  0x5E
#define SHIFT         0x35

void setup()
{
  // Start comms
  Wire.begin();
  Serial.begin(19200);

  delay(50);  // Delay so everything can power up

  // Read the sift bit register from the module, used in calculating range
  Wire.beginTransmission(ADDRESS);
  Wire.write(SHIFT);
  Wire.endTransmission();

  Wire.requestFrom(ADDRESS, 1);
  while(Wire.available() == 0);
  shift = Wire.read();
}

void loop()
{
  // Request and read the 2 address bytes from the GP2Y0E02B
  Wire.beginTransmission(ADDRESS);
  Wire.write(DISTANCE_REG);
  Wire.endTransmission();

  Wire.requestFrom(ADDRESS, 2);

  while(Wire.available() < 2);

  high = Wire.read();
  low = Wire.read();

  distance = (high * 16 + low)/16/(int)pow(2,shift); // Calculate the range in CM

  Serial.print("Distance is ");
  Serial.print(distance);
  Serial.println("CM");

  delay(50);
}

Simple Example (works by giving voltage)

int sensorpin = 5;                 // analog pin used to connect the sharp sensor
int val = 0;                 // variable to store the values from sensor(initially zero)

void setup()
{
  Serial.begin(9600);               // starts the serial monitor
}

void loop()
{
  val = analogRead(sensorpin);       // reads the value of the sharp sensor
  Serial.println(val);            // prints the value of the sensor to the serial monitor
  delay(100);                    // wait for this much time before printing next value
}

Schematic


texts: it is from a light and service reminder timer board. it looks like ATtiny26 but osc connection is on wrong pins(3-4 not 7-8) pin 6 is gnd, 16 is marked Hz, 10 is light relay signal (17 hours on 7 off), 19 is to service led(6-month interval) . there is a bi-weekly service indicator led aswell. is it possible this is a ATtiny26 and the external osc is for timer?


texts: Power amplifier simulation and real time experiment mismatch problem

texts:
Thanks in advance to anyone who will take the time to read my first post here.

At present, I am doing a simulation of a power amplifier in LTSPice. The schematic and relevant files are uploaded in a zip file attached herewith. I have designed a PCB based on this design. I have used 15 V for gate biasing and 15-20 V (Vdd) for drain biasing in the uploaded schematic. The channel is on when gate voltage reaches about 2.1 V. I am using a function generator driven 1.5 V peak to peak sine signal having 7 MHz frequency (AC transient analysis shows around -4 dB gain at this frequency). From the ac transient analysis, I can see that in this configuration I am getting 0.9 V peak to peak at the output in the simulation. Another observation is that as Vdd is increased, gain also increases.

However, in the practical circuit, I am not getting any output, just noise. Even when I increased Vdd upto 25 V, I did not get any RF output. I know I am doing some mistakes which I am not being able to identify so far. I would really appreciate if anyone can provide suggestions.

Thanks in advance.


texts:
My university's student electric racing team has to test a large number (250) of lipo cells before using them in our electric car.
Our testing methodology will be approximately like this:

Discharge.
Charge at 1C
Let cells rest for a specific period.
Discharge at constant current and measure capacity.

I've heard that some bad cells may charge and discharge to the nominal capacity if they are charged immediately, but do not hold up after time. Is this correct?

I've been unable to find any hard data on the interval between charging and discharging required to differentiate good cells from bad ones -- how long do we need to wait to know if the cell is good?

Sources of empirical data would be especially appreciated.


texts: transimpedance amplifier configuration in a polygraph circuit

texts:
I am working through an assignment to design a polygraph circuit which works off skin resistance and in the brief, it specifies that a transimpedance amplifier must be used. I have never used one of these devices and have got my circuit to work. but I have connected it in a non-inverting configuration with the feedback that looks like a Schmitt trigger.
My circuit works and I have shown a lab technician from my university, but he also has not worked with transimpedance amplifier, however he told me he does not see why it would be allowed especially since it is working. I do not know if I can connect a transimpedance amplifier in a noninverting configuration. I have not really seen much online about this topic nor in the device’s datasheet. Some of my classmates do not believe this would be allowed. Can anyone advise me if what I have done is allowed or not?
Many thanks.


texts:
I made a cooling unit with two peltier(12706) with hot side attached to heatsink with fan. And cold side with waterblock i.e (heatsink + peltier(hot side with heatsink) then waterblock then another peltier (cold side with waterblock) then another peltier + heatsink)
When I power the unit the waterblock get cold but what I run water through waterblock it doesn't cool . Why???


texts: What is the advantage of optical TOSLINK over RCA coaxial cable?

texts:
A popular standard for the transmission of digital audio between audio devices has been the AES3 standard (also known as S/PDIF). The standard sends stereo PCM audio and of often found in consumer electronics. The standard specifies multiple interconnection types with RCA coaxial cables and optical TOSLINK being two most popular.

Commonly in audio manuals, it is commonly noted that the optical TOSLINK provides a superior connection due to the superior aspects of optical cables in general. I understand the physical medium of optical fibers are less prone to noise and possess higher theoretical bandwidth. Personally, I have never noticed a difference between the two.

I want to ask, within the scope of digital audio transmission, it is their any observable or measurable differences between the two cables? If not in audio fidelity, is there a difference in transmission quality? Is TOSLINK more than an overpriced cable?

RCA connectors are cheaper and more universally available.


texts: Using a BLDC motor for regenerative braking

texts:
I am planning on using a BLDC motor to drive a small go-kart like vehicle. I would like to implement regenerative braking, but am having trouble finding certain details.

My main concern is being able to quickly stop the vehicle. Is there a way to control the braking speed? I assumed that when powering a load with a motor (when being used as a generator), the motor would become harder to turn, which would act like a brake. Is this the case?

If so, I figured I could use a PWM-like circuit to essentially change the duty cycle of when energy is being drawn from the motor. A higher duty cycle would mean faster braking. Would this be an appropriate solution?


texts: Why is this hex file different than the code programmed onto the device?

texts:
I have a design using an STM32F105. My application written in C; using Eclipse and gcc. I have been using Eclipse (with OpenOCD and an ST-LINK/V2 programmer) to write the firmware to the devices. Now I need to program many devices and am looking for a faster method.

The ST-LINK Utility software seems to be a fine choice. You can point it to a .hex file and set it into "automatic mode". It then detects when a device is connected to the programmer and writes to it. Then you connect another device which will get automatically written. Very smooth.

So here's the problem: It appears that the firmware written to the device by Eclipse is actually different than the Eclipse-generated hex file.

This is what I'm seeing:

I program Device#1 via Eclipse. I remove the programmer, reset the device, and it works fine.
I find the Eclipse-generated .hex file (.../Debug/application.hex).
I program Device#2 using the ST_LINK Utility and this file. I remove the programmer. The code doesn't run, even after a device reset.
I use the ST-LINK Utility to read the (working) code directly from Device#1.
I use the ST-LINK Utility to program this code onto Device#2.  Now, Device#2 works correctly.

OK, so the generated .hex file must be wrong.  I can use the ST-LINK utility to compare the two hex files (from steps 2 and 4). It shows that the files are identical until the end:

(click to zoom if you need to)

Finally, my questions:

Why is the generated .hex file incorrect? Perhaps Eclipse uses gcc to create the hex, and then modifies it en route to the device? How can I make Eclipse output a hex file that matches the code that it programs to an actual device?

Note that I am building the "Debug" configuration. When Eclipse connects to the target device it programs the code and allows me to debug.  If I remove the debugger hardware, the device still functions.  That is, the code works fine without the debugger attached.


texts: Is it possible to convert 6V 4A (24W) DC to 12V 3A (36W) DC using step up booster?

texts:
I have Yamaha RX100 1996 model which has 6 V power supply.

This 6 V power supply is the main drawback for the headlight, where the circuit diagram is shown in these images:

The official bulb requirements are given below:

For further details about the circuit diagram open the link below (page - 63): Yamaha-RX-100-Workshop-Manual.

I plan to convert 6 V 25 W to 12 V 36 W using either this boost converter:

6V 9V to 12V DC DC Boost Converter Step Up Module, 1A 2A 3A Power Supply, or;
6V to 12V Step Up Converter, DROK DC 12V Boost Converter DC 5V-11V to 12V Voltage Regulator Module 3A 36W Volt Transformer Power Supply for Car Stereo Radio LED Display

Is it possible or not?


texts:
I am trying to setup a simple server in the port :80 with a esp8266 module.
I flashed it to the most recent version and it seems to work ... but it is like it doesn't respond to request when I access it through the explorer.
The most annoying part for me is about the +CIFS command
It returns the following:
AT+CIFSR

+CIFSR:APIP,"86.186.85.186"
+CIFSR:APMAC,"1a:fe:34:9b:c3:83"
+CIFSR:STAIP,"102.106.51.178"
+CIFSR:STAMAC,"c0:ca:41:00:47:40"

My network is 192.168.1.X , 255.255.255.0, 192.168.1.1
According to this thread I found

Station (STA) is when your ESP is connecting to your home wifi.
Access Point (AP) is when your ESP is broadcasting wifi for you to connect to.

If I execute a ping on the 86.186.85.186 is ok.
Haciendo ping a 86.186.85.186 con 32 bytes de datos:
Respuesta desde 86.186.85.186: bytes=32 tiempo=67ms TTL=51
Respuesta desde 86.186.85.186: bytes=32 tiempo=67ms TTL=51
Respuesta desde 86.186.85.186: bytes=32 tiempo=67ms TTL=51
Respuesta desde 86.186.85.186: bytes=32 tiempo=67ms TTL=51

Estadísticas de ping para 86.186.85.186:
    Paquetes: enviados = 4, recibidos = 4, perdidos = 0
    (0% perdidos),
Tiempos aproximados de ida y vuelta en milisegundos:
    Mínimo = 67ms, Máximo = 67ms, Media = 67ms

Command sequence:
AT
OK

AT+RST
OK
WIFI DISCONNECT
ets Jan  8 2013,rst cause:1, boot mode:(3,0)

load 0x40100000, len 1856, room 16
tail 0
chksum 0x63
load 0x3ffe8000, len 776, room 8
tail 0
chksum 0x02
load 0x3ffe8310, len 552, room 8
tail 0
chksum 0x79
csum 0x79

2nd boot version : 1.5
SPI Speed      : 40MHz
SPI Mode       : QIO
SPI Flash Size & Map: 4Mbit(256KB+256KB)
jump to run user1 @ 1000

rlŽ‚rlŒžâ
ready

AT+GMR
AT version:0.60.0.0(Jan 29 2016 15:10:17)
SDK version:1.5.2(80914727)
compile time:Jan 29 2016 19:07:08
OK

AT+CWMODE?
+CWMODE:2
OK

AT+CWMODE_CUR=3
OK

AT+CWJAP_CUR="XXXX","XXXX"
WIFI CONNECTED
WIFI GOT IP
OK

AT+CIFSR
+CIFSR:APIP,"86.186.85.186"
+CIFSR:APMAC,"1a:fe:34:9b:c3:83"
+CIFSR:STAIP,"102.106.51.178"
+CIFSR:STAMAC,"c0:ca:41:00:47:40"
OK

AT+CIPMUX=1
OK

AT+CIPSERVER=1,80
OK

Am I missing something?
EDIT:
Expected result, more or less like (To be clear, I do not use any arduino  sketch or whatever. I just use the serial monitor. The behaviour is the same using putty.
I connect to the ESP8266 chip using a usb-to-serial cable.

But right now the explorer just says not found.


texts: Do the resistors affect every component of the circuit?

texts:
I've noticed something strange in the circuits schemes I saw in a book.

Let's say that there is an LED and it's anode is connected to a 5V power source, and it's cathode is connected to ground.

Obviously there must be a resistor between the LED's anode and the power source, but in some circuits schemes the resistor is between the LED's cathode and ground, and strangely for me, it works!

How?

I mean in the first example the resistor is before the LED so it can decrease the current so the LED doesn't burn or explode, but in the second example how can the resistor affect the delivered current to the LED and the resistor is after the LED?

The electrons will reach the LED before they reach the resistor so how can the resistor affect components behind it?


texts: Serial Peripheral Interface (SPI) vs Two-Wire Interface (TWI, I²C) wire length

texts:
I'm using Arduino DUE to read data from an IMU(inertial measurement unit) sensor (MIKROE-1577, MPU-6000)

This IMU sensor supports both Serial Peripheral Interface (SPI) and Two-Wire Interface (TWI, I²C). According to the datasheet,

400kHz Fast Mode I2C for communicating with all registers
1MHz SPI serial interface for communicating with all registers (MPU-6000 only)
20MHz SPI serial interface for reading sensor and interrupt registers (MPU-6000 only)

Note that the Arduino DUE can set the SPI clock using setClockDivider()
and I generated 1MHz, 4MHz, 8MHz clock frequency.

My situation; I have to make a long wire to place this IMU sensor on a table.

I prefer to use SPI because it is faster than TWI.

But if I set the SPI clock frequency to 4 MHz or 8 MHz, I noticed that the SPI signals become a sawtooth wave, not like a pulse wave, if the wire gets longer.

I really want to read the IMU data with an SPI clock of 8 MHz.
How can I calculate the wires' length, which doesn't distort the waveform strongly, if I want to set the SPI clock frequency to 8 MHz?

Also, in contrast, if I choose the 400kHz Fast Mode I2C, how long can I extend the wires?


texts: What advantages does CPLD have w.r.t microcontrollers in driving MOSFET drivers in inverter?

texts:
I have seen some designs where CPLDs have been used in driving the MOSFET driver in an inverter circuit. What advantage does is provide with regards to driving the same using controllers like TI piccolo c2000 series?
Note: I’ve never used CPLDs and consider my self as a newbie in that area. Would like to hear some conceptual understanding or suggestions for reading on the same.
Thanks a lot for your time.


texts: What are these gaps in PCB polygon pours near vias of the same net?

texts:
When adding polygon pours to a power layer on my PCB in Altium Designer (v17), I'm getting weird clearance gaps near vias. The poly and vias are connected to the same net. I'm new to Altium, so I'm not sure what's causing this.

I've checked Design Rules > Polygon Connect and tried both Direct and Relief connect (no change). I don't think it's a relief because if it was it would encircle the via.
On the polygon properties, I have tried turning on/off Remove Dead Copper, Remove Islands by Area, and Remove Narrow Necks, but the gaps persist (albeit with some corner sharpness differences).

I put some vias near the edge of the poly to try and figure this out:

I suspect there may be a design rule affecting it, but I am not sure what to look for.

What should I check in Altium that controls gaps around/near vias on polygon pours of the same net?


texts: Voltage divider but don't know current requirement, so how to pick the ratio

texts:
I want to connect my little RS232 to TTL converter to a 5V power supply but the converter needs 3v3. So I thought, even with my very little electronics knowledge, I could knock up a potential divider to do this...

... on considering it I realised I have two resistor values to calculate and one equation because I don't know the current that the device would draw.

R1/(R1+R2) == 3.3/5

So my question is should I just choose resistor values that are as low as possible so the current isn't limited significantly but I still achieve the same voltage across the load? Would this work? Thanks in advance :)


texts:
The Cortex-M processors are getting faster and more powerful. The Cortex-M7 has just been announced. Yet these cannot run Linux (other than uCLinux) because the chips lack an MMU - Memory Management Unit.
Is there an external MMU chip? Wikipedia refers to the Motorola 68851 and Zilog z8015, but both are rather old. Ideally, an up-to-date version would allow you to add DIMM memory modules to an Arduino Due (as an example).
Is such a chip available? Or is this the kind of custom task you can only do with an FPGA?


texts: Diminished data rate with logic output optoisolator

texts:
I am using a logic output type optoisolator (H11L1S) that has a nominal data rate of 1 MHz, yet in practice I can't even achieve 100 kHz.  Where am I going wrong?  Is this maximum data rate unattainable?

Here is the relevant circuitry:

I am driving the LED at 2.8 mA, which is well above the minimum turn-on current of 1.6 mA (plus 10 % guard band suggested by the datasheet).  Q18 is a prebiased NPN with 2K2 base resistance and 47K pull-down resistance.  Below is a scope capture of the clock signal (ADC_SCK, yellow) and LED cathode (blue).  Once the transistor turns off the cathode voltage takes more than \$5\mu s\$ to reach +3V3 -- i.e. the LED turns off very slowly -- such that the receiver does not register the change in state.

This means the hot-side circuitry (ADC_SCLK, blue) sees a very slow clock:


texts: What exactly does a conduction angle mean in semiconductor electronics?

texts:
I read a question about conduction angle at How to calculate the conduction angle of a CVD diode? . However, I am confused as to what is the "exact definition" of conduction angle. There are two possibilities in my mind and I'm unable to find out which one is correct

Angle during one full cycle (2pi) during which the rectifier is conducting?
Maximum length of a continuous interval in a full cycle (2pi) during which the rectifier is conducting.

I recall reading the second one somewhere, but don't know if it is true as I can't find an authentic source.
Based on these definitions, the answer to the linked question will not change, but I'm not sure whether that will be the case for other rectifiers as well.
If I am totally wrong on this matter, could you please give the definition of conduction angle. I am unable to find an authentic source.


texts:
I want to implement signed software updates to my MCU, It is connected via USB and I am using the USB DFU to upload a firmware to it.
I want that only signed firmware will be allowed to be uploaded to the device, if possible I also want to disallow reading of the firmware.
What is the standard way to implement this on the MCU level?


texts:
Lets consider a p-sub MOS Capacitor working in Inversion mode. When the Gate potential is increased, a lot of electrons start appearing at the oxide-semiconductor interface.

Are these electrons just the minority charge carriers present in the p-type? If yes, then how can there be so many minority charge carriers?


texts: Identify two ICs from Laptop Motherboard

texts: Can anyone identify these two ICs from a laptop motherboard?


texts: reading a DC voltage into an android phone microphone port

texts:
I have been using the microphone port of an android phone to read AC voltages (as it is capacatively coupled).

What if I want to read DC voltages?

I have considered...

turning DC into AC via an oscillator
using a PIC microcontroller to read an analogue voltage and send a high/low bitstream to the microphone input containing this information

I think (2) is the best way to go. What is the easiest/quickest/cheapest way to get a PIC to read an analogue voltage and output a bitstream in this way?


texts:
I'm using the RDM6300 125kHz reader module in combination with Arduino Uno to read my tags.

The tags themselves have their ID as a label. When I then try to read the cards, I receive another ID as the indicated label. For example:

Tag label: 0009471985

Reader Output: 0x85009087F163 = 146237471322467

But when I ignore the first and last byte, the ID is correct:

Reader Output: 0x85009087F163 = 146237471322467

Ignoring first and last byte: 0x009087F1 = 9471985

This happens with all my tags I read. But the bytes change for every tag, so they can't symbolize the beginning and ending of the transmission.
When I use an other Chinese reader, it outputs me the correct ID as decimal numbers. Should I now ignore those two bytes, when creating access control and focus on the ID indicated on the tag? And what do those bytes represent? Are they a checksum?

Thank you!


texts: What does JB instruction mean in Assembly

texts:
I am looking at an ST7066U controller for a 2x16 LCD, and in their datasheet, they have these Assembly instructions that I would like to change to C code.
CHK_BUSY: ;Check Busy Flag
CLR RS
SETB RW
SETB E
JB P1.7,$
CLR E
RET

What does JB P1.7, $ mean?


texts: Finding the voltage across nodes A and B

texts: I've tried solving it and have managed somehow to make out the answer but it isn't in a systematic way.


texts: What happens to the gain of a switched capacitor circuit when a resistor is placed in series with the input voltage driving source?

texts:
Why might that happen?

This was an interview question I received


texts: how to find impedance of inductance with square wave input

texts:
I know the impedance of the inductance is: 'jwl'; but this is correct with  sinusoidal input; now my question is:

how to calculate the impedance when the input is the periodic square wave(like a digital clock)?

any help will be appreciated.


texts: Decreasing sensitivity of a touch paddle

texts: I made a simple touch paddle using the circuit here. It is too sensitive and also triggers when my finger is only near one of the sides. How can I decrease sensitivity?


texts: Three Phase System: A balanced three phase three wire system has a y connected load

texts:
Each phase contains three loads in parallel: -j100, 100 and 50+50j ohm.b Assume positive phase sequence with
Vab = 400 /__0 V
Find Van and IaA and total power drawn by load.

I found line voltage as
$$Vline=Vphasor∗sqrt3=231volts.$$
But I can't get the correct value of Ian and power. I tried
$$Ian=Van/Zphasor$$

by putting

Van= 231/__-30°

and calculating

Zphasor= sum of all impedances
 Zphasor=-j50+150= 158/-18.4
but I cant get correct answer for Ian.
Correct answers are: 4.62/-30° and 3200 W.


texts: Circuit for childrens "electric" toy/game

texts:
Some might remember a childrens game where you have a sheet of symbols, holes in it that lead to contacts, and then you have two wires and whenever you have two symbols that match you put some cables onto those two, and a light shines that tells you, you were right. In my childhood this game was simply called "electric" and I want to create a similar game for my kids too, that doesn't fall apart as soon as you look at it.
My goal for the design were

Will fit into an approximately test tube sized transparent plastic tube
For the looks is a freeform circuit
Does not use anything more complex than a transistor (i.e. only three pin TO devices, no more pins or flatpacks or so)
When the contacts are closed, will light an LED for about 2 seconds
Will draw very low (ideally none) power when not active
LED will not go out while contacts are closed
LED will turn on to full brightness, and when it goes off it shall not dim, but instantly go down to zero brightness. Some not really visible brightness changes (i.e. current fluctuations) are ok though.
Amount of "P " transistors (PNP, PMOS) or other uncommon ones is low or zero. Ideally would be NPN only.

My design started out with some simple latching switch, adding timeout and other requirements as I went along, and what I came up with in the end is (ignore V2-V4 and S1, they are for testing the leads actions):

Basically around Q1 and Q4 is the latching switch, C2 is charging up until M1 causes the switch to latch off again; Q5 is there to hinder charging of C2 as long as the leads are connected.
Unfortunately that feels like too much components for this task. Also -- while the LED stays on while leads are connected -- it does not really do retriggering, at least not for very short contacts. This might be fixed by adding yet another transistor in front of Q5 to increase the current it shunts C2 to ground with, but that would mean: yet another component.
So the question is:
Can this be simplified to less components, or at least NPN only? Maybe at the same time solving the retrigger problem, or can that at least be solved without adding transistors?
Note: I might have forgot to mention some requirement because it is evident for me how the game should work, but not for you if you are unfamiliar with it. If you have the feeling that it would be the case with your suggestion, I would appreciate if you ask if "behaviour XYZ" is ok too.


texts: What should be the V specs of a step down transformer for a 10amp car battery charger

texts:
I was looking to create a 10amp manual charger with variable voltage and current option for flooded lead acid battery (normally used in cars).

I only know some basic electronics and usually make solutions by integrating off the shelf modules.

For this project I have to first buy or order a custom built 10amp step down transformer  but I was bit confused what should be the secondary output voltage for this transformer

To charge a FLA battery we usually need up to 14.2V and to equalize we need 15V that is maximum output we need from a battery charger

Therefore my question is should I look for a transformer with exactly 15V secondary output? or higher than this and why? because some online battery charging circuits are using 18V transformers.

Thanks,


texts:
I have designed a 50 W, 12V-5V buck converter operating at switching frequency 200kHz.This is just for understanding practical converter circuits, so I made a totem-pole bjt driver circuit for IRF640N.
Can someone help me out with the isolation required for the MOSFET? At first I had placed the switch in the return path, but this design is for closed loop control, so I think I might have trouble with feedback noise if I don't place it in the go-path.
I know there is pulse-transformer isolation & digital isolation, but I'm not sure how to incorporate that.
EDIT: Parallel to trying to do the isolation part, I was looking for a gate driver IC, but I'm stuck at how to choose one.Any inputs on that front is helpful too.


texts: Pin out clarification, I need some help understanding the pin outs

texts:
What do the pins "/CS", "SCK", and "SDI" mean? From my bad understanding of this diagram, I only have to run 3.3V to "/CS", "SCK", and "SDI".
Is this true or am I way off?

Let me know in the comments if you would like more details.
Here is the Link: http://www.newhavendisplay.com/specs/NHD-3.5-320240FT-CSXN-CTP.pdf


texts: How can I tell the size of a barrel power connector?

texts:
Spring cleaning, and I'm trying to get power supplies for all my devices with missing power supplies. They're all the typical barrel power connector, and I'm having a dickens of a time trying to figure out the pin/hole diameter.

I ordered the power supplies I needed based on outside diameter (e.g., 5.5mm in my example below) and was surprised to discover that while the jack fit, the center pin did NOT. How do I prevent this from happening in the future? Do they even make calipers that can get into the hole to measure the pin diameter?

Radio Shack has their little keyring behind the counter with every known tip size, but all they can get from that is which stock number fits on their universal wall wart. Personally, I think that these types of "universal" kits are the worst thing to happen to electronics in, like, FOREVER. Too many parts to misplace and the tip-to-cable connector is almost always proprietary.

If I try to pump them for information about what the outer and inner diameters are, they want to know if I'm happy with my current cellular provider. As you may surmise, I'm not a big fan of trusting my local Radio Shack for electronics guidance.

So...that leaves me with a bunch of power supplies that don't fit their devices, and me a little peeved that I have to deal with RMAs, return shipping, etc., especially when I really don't have a clue how to figure out what to order. That also begs the question about how to ensure that I buy the right jack when designing something that NEEDS wall wart power.

Where do I even start? Anyone have any ideas on how to finding the correct barrel & pin diameters when I don't have specs on the jack? Is it really trial and error? or is there some measurement device that's available to help?


texts: How does this circuit with inverters work?

texts:
What this does this circuit do?  I suspect it is an amplifier, but don't know how it amplifies.

For example Inv 5 and Inv 6 are connected in parallel with reverse sides but there is a wire between them, wouldn't that wire just cancel whatever their function is and they are there for ?

How do Inv 7 and Inv 8 affect gain of the circuit if this actually is an amplifier ?

Some information :

Assuming size of Inv7 and Inv8 3 times other inverters and I(inverter 6) =100uA and input CM equals to voltage of Point A.

Find current of other transistors Va=Vdd/2=1.5


texts:
I would like to check the health of some large capacity (circa 10,000mAh) 5V USB battery packs that have been sitting around for a long time.  There is another post "How to monitor voltage and charge status in USB battery pack" but this didn't say when to discard a pack.

How come they're 5V when LIPOs are 3.7V? i.e. is it 2S with buck converter or 1S with boost converter?

I looked at a Skyrc S60 balance charger which can measure resistance and other things on drone Lipo batteries but these seem to have balance  connector leads.  So I can't see how to connect a 5V retail battery pack with female micro-USB charging socket and normal female USB supply sockets.

I think the balance charger is for drone batteries and so may be unsuited to check health of retail 5V battery packs.  As I understand it such battery packs have extra circuits to make them safe e.g. prevent overcharging.  Presumably that makes it harder to measure resistance etc.  Am I correct?  Is it worth me buying a S60 for this?

So I'd like to find a way to check health of battery pack - ideally other than waiting to see if case starts blowing larger due to gases from deterioration (eg spinning case to see if cases have caused case to curve out).  Would a low output voltage be such an indication e.g. if I only got 4.5V then it's time to chuck?

If the battery pack is ok then can I charge and draw power from it at the same time i.e. as an uninterruptible power supply?  I have a pi zero that I'd like to power from a LIPO connected to a large solar cell.


texts: Radio Waves reach in function of frequency

texts:
What is the relationship between the reach of a RF signal and its frequency?

What I mean is: If power is kept constant, should I use high or low frequency waves to get a better reach? Why?


texts: Single supply op amp with input attenuator

texts:
I'm designing a guitar headphone amplifier that uses a single supply op-amp as the output stage to the headphones. I'm using a potentiometer after the final JFET stage and before the op-amps as a volume control (so that I can keep the overdrive tone from the final JFET stage).

The part I'm unsure about is the C9/RV3/C14 part of the schematic. I've used C9 to block DC (from the JFET bias) to avoid potentiometer crackle, and C14 blocks DC to the inputs of the op-amps.

My question is, can I connect pin 1 of the potentiometer to V_gnd (currently connected to DC GND) and omit C14? If that's the case, does R14 stay connected, or does RV3's V_Gnd connection suffice as a reference for the op-amps? If RV3's connection alone is relied on, I'm worried that the changing resistance between the op-amp and V_gnd voltage divider will cause instability, but having both C9 and C14 seems superfluous.

Also, is DC GND the best point to connect C15 and C16, or would connecting them to V_gnd be beneficial?

Thanks!


texts:
I have a hard time trying to understand why Thevenin’s Theorem is the way it is.

As per the diagram below, I understand why we take our “Thevenin resistance” that way. But as far as the voltage is concerned, I am completely lost. Why do we take the “Thevenin voltage” to be the voltage drop across the points A and B? By doing that, won’t the voltage drop across AB in the equivalent circuit be less than the original value, since part of the voltage must have been dropped across the “Thevenin resistance”?

This has been bothering me for two days now. Please help.


texts: What are these metal plates covering parts of PCBs called?

texts:
I am trying to fix my wireless router, but one of the parts is under a metal plate.

What are these metal plates called?

This is what it looks like when it is removed:  (The gold coloured plating on the bottom left, next to the grey antenna wire is where it is attached.)

How would I go about removing them?


texts: I'm working on a project in which I have to get current location at every 10 sec interval. I've used sim808 (GSM/GPRS & GNSS) using which I execute AT+CGNSINF command to get the location. I get that location string in terminal using serial communication. As I'm working with this device at my place. sim808 gives me complete data at every 10 sec with updated time and 4 satellites in view and works fine as I expected. But as I go with my car to test the project. sim808 do not give me the updated data. It freezes at a position and gives me that old data at every 10 sec even time also. Now I do not know what problem would be there? What should I do to make this thing work?


texts: UART: interfacing b/w 3.3V and 2.4V - current limiting resistor

texts:
I need to interface a 2.4V IC and a 3.3V IC via UART i/f. The VIH spec of the 3V3 IC is low enough to allow UART_TX_2V4 to be directly connected to UART_RX_3V3. My main concern is the UART_RX_2V4 pin which would see 3.3V levels and see current sinking in to its protection diodes. TO deal with this, I can have a current limiting resistor - shown in circuit below.

Is this an acceptable way of interfacing or is there something I tend to lose by not going for a level shifter?
Also - what spec would be I need to check on the 2V4 IC side to make sure that the UART_RX_2V4 pad is not damaged?

simulate this circuit – Schematic created using CircuitLab


texts: Debugging my bipolar stepper motor design

texts:
I'm trying to connect a NEMA 17 Bipolar Stepper Motor to an Arduino Uno using an L298N Stepper Motor Controller Module and control its speed using a 10K potentiometer.

I haven't found any examples online on how to do this explicitly (using the L298N controller module), so I've resorted to trying to design the circuit myself.  This is, literally, my very first attempt at designing a circuit myself.  I have no background in electronics or electrical engineering.  I've gathered as much info as I can from the arduino website and the manufacturers of the motor itself.  This much I'm certain of:

The motor should be powered independently from the arduino, using 2.55 volts and 1.7 amps.
The motor and its power source must be connected to an H-bridge before connecting to the arduino inputs.
Pairs of wires on the stepper motor are connected and can be determined easily by hooking an LED light to a pair of wires and rotating the motor manually.  Connected wires will cause the LED to light up.
All grounds should be connected together.

In addition to this, I'm also making a few (hopefully true) assumptions:

The L298N Controller module should provide the necessary H-bridge.
The H-bridge inputs should be connected to a contiguously indexed array of digital pins on the arduino.
Despite the specs indicated the need for 2.55 volts, a 2.5 volt source should be sufficient for this motor.
Since a 2.5 volt source is not readily available, I can create one with a voltage divider.
Reversing the polarity of the stepper wires to the Controller Module (h-bridge) does not matter.  That is, if a pair of connected stepper motor wires Wire1 and Wire2 are wired to Out1 and Out2 on the L298N Controller Module (respectively), then hooking up Wire1 to Out2 and Wire2 to Out1 would produce the same effect as the original wiring.

Based upon the above facts/assumptions, I created a schematic of how I think everything should be hooked up:

Note that the two instances labeled 2.5V are connected to each other.  Additionally, all grounds are also connected together.

I would like some feedback from the community on my proposed stepper motor design.  In particular, I would like to know if my assumptions above are correct and whether I can obtain the necessary current for my stepper motor using my voltage divider as displayed in the picture above.  Any suggestions to improve / ensure functionality would be greatly appreciated!

If anything is unclear about my schematic or assumptions, please let me know and I will clarify as best I can.


texts: How to interface a quadrature encoder with PIC?

texts:
I'm developing a prototype that uses a quadrature encoder to measure it's linear displacement. The encoder is attached to the prototype body and has a wheel in it's shaft. As the prototype moves straight forward the encoder measure the linear distance. All the trouble around the conversion between linear/angular units have been worked out.

The reason to measure the distance with an encoder is that i NEED to know everytime that the prototype has traveled exacly 1 mm (1 millimeter = 0.0393 in). Everytime it moves 1 mm, PIC activates another system.

The way it has been done before I started working on it is by reading the encoder with a PIC (16F688) in it's I/O ports. It was kindda ok but when I added some features to the PIC code, if the prototype linear speed is greater than ~1.77 in/s (~45 mm/s) PIC starts missing the encoder count.

I've tried using the IOC (interrupt on change) from portA to read the quadrature signal (channels A and B) but it wasn't effective.

I know that there are dsPIC's but I need to solve this in my board and I have only 14 pins to do so lol. So i found this PIC16F1825 which has a higher (4x) freq. Could that (my PIC low freq) be my main problem??

I'm was thinking about using the LFLS7183 UP/DOWN signals with the timer/counter from PIC or another counter IC so that would reduce the amount of signaling to PIC. Would that work? Which counter should I use? I don't have 8 pins in my PIC to use as in those http://goo.gl/2Wc3d.

My encoder isn't my problem, I've checked and it can track as far as 76 feet/s for my wheel radius.


texts: Minimum voltage input for thermoelectric unit

texts:
Context: I am trying to make a drink cooler with a thermoelectric unit (peltier unit). I want to supply the minimum amount of energy as possible to the peltier unit. Now on my peltier unit, it says "15V" (and 68W). I am not sure whether it is recommended, minimum or maximum.

I would have probably just tried to find a batter that can provide 15V but there were two discoveries that I made which suggest I could possibly get away with providing less voltage power supply.

I read somewhere that peltier units in general can handle between 3 and 15 volts.
I bought a drink cooler using a peltier unit and it is charged by a USB (5V).

Questions:

Are peltier units capable of taking varying amounts of voltage without hindering its quality or damage it?
If so, how would I go about finding what it needs as a minimum voltage input?
Does all my above questions not matter because if I lower my voltage, the peltier will draw more current to meet the power rating (68W)?
Does the power rating of 68W mean, "I need that power as a minimum all the time!"


texts: Measure volt, amps, watt and kWh of an external 12 V DC system

texts:
I saw online some cheap hardware ~10$ that can measure volt, amps, watt and kWh and display the results on an LCD screen.

I could buy and plug these on my 12 V solar panel system to monitor it. (5 of them) (Circuit is between 6A and 20A)

But thinking about it, I wish to use my Raspberry Pi to monitor these numbers. - Trigger some events on specific values, log these values over the year to compare efficiency between seasons, etc., and display all of it in a web interface or whatever. (That won't be a problem.)

My question is : What kind of hardware can I use to simply measure the volt, amps, watt and kWh and send the value to my RPi ? (in 5 different places in the circuit.) - Of course i can do the math later for watt and kWh. :)

Answering my own question, so you can tell me if it's a good idea.

I already made a working system with an ADC (Analog to Digital Converter) that can convert the voltage to an LED with a potentiometer with some C code. - PCF8591

Can i simply buy 4 ACS712 and send 4 different analog signals to the PCF8591 ? (It does have 4 analog inputs)

And then I should be able to use I2C to send to my Raspberry Pi.


texts: Why do batteries not last as long in a cold environment?

texts:
I know that batteries don't lase as long when they are used in a cold environment, but why is that?

For normal conductors resistance decreases as temperature goes down, so shouldn't the internal resistance of a battery go down as well, making it more efficient?

I know that the resistance of semiconductors increase as temperature goes down, but most simple batteries (such as Pb-Acid, NiHm, and Li) don't have any semiconductors in them, do they?


texts:
I am designing a CAN device where the user may switch between it being the end device and thus with terminators or vice versa.

Now, there is no need to drive it digitally using MCU, I would actually prefer using a DPDT (or DPST) slide switch only. However, I am not sure if it's a good idea to connect it directly like this:

A solution using optocouplers seems to be rather frequent from what I've seen and it seems more clean - separating the CAN from the switch - but I am not sure if it is not an overkill considering driving it from MCU is not used:


texts: What is the current draw of an Arduino Due board when sleeping?

texts:
I have application which requires 1 year+ operation on a small battery (2xAAA or coin cell). It will be spending 99.99% of the time sleeping only requiring an internal timer for periodic waking and wake on external interrupt. I am considering the 32 bit ARM based Arduino Due board, but nowhere can I find information on how much current the board will consume while the MCU is sleeping.

From experience with other boards, the low power capability of the MCU is negated by power regulators and power LEDs etc.


texts:
Being far enough from everything about electrical engineering and so on, I'm sorry in advance for a dumb and possibly asked here in threads earlier such question.

I have only the next data on batteries:
 - Battery Current Limiting Coefficient
 - Battery Capacity
 - Load Shutdown Voltage.

There's also an Average Discharge Current(A), but this variable is gotten from the tests of already used batteries and can be even negative (like -44.3), so I dont think I can use it.

I wonder can I calculate the battery discharge time (approximate time of battery life before full discharge) using given parameters? I found many formulae but there's always a lack of at least one element to use the function.


texts: About charging Li-ion batteries in mobile devices

texts:
I've got some questions about charging Li-ion batteries in mobile devices.

Does mobile phones that are made by major manufacturers like Samsung have solutions for charging safety in their devices? If there is, how does it work?
What happens if charging voltage or current exceeds the levels of the charging battery? Can the safety solutions prevent all the unexpected damages? For example, battery designed to be charged at 9V/1.67A is charged by 12V/5A or suddenly gets shorted.
Is there any situations happening during the charge that can cause li-ion battery to explode? Like electrical shorts or sth...?

Thanks in advance.


texts:
In pretty much all modern computers and mobile devices, the CPU can have varying amounts of memory (either to be configured by the user or fixed at point of assembly). Apart from historical form-factor reasons (where GPUs just came as 'a card' that was actually composed of the GPU itself, power management, I/O and memory), is there any fundamental reason (ie, electronic engineering reason, not marketing) why GPUs don't come in different amounts of memories for a specific GPU model?

Of course, different models of GPU might have different amounts of memory, but to my knowledge, a specific GPU model will always come with a specific amount memory (for example, the AMD R9 280x in my workstation always has 3 GB of memory).

For general consumer applications, I can understand that there might be a cost/complexity argument - it is simply easier and cheaper to have one configuration. But for applications that are more GPGPU oriented, it seems like linking memory configuration to processor configuration could be limiting? (for example, my place of work recently acquired a number of GPGPU servers. Each of the GPU's comes with I think 24 GB or RAM, but the FDTD simulations they run don't need anywhere near that amount of RAM).


texts: How to make an .sof upload to an Altera Max10 stick

texts: I have a Max10 dev board with a 10m08 chip on it. I made a simple counter to blink the LED's. My counters have asynchronous resets, and my asynchronous reset has a circuit to keep it low for two clock cycles and prevent metastablity. I reset the fpga and it the counters stop (they all go to zero), it only starts counting when I upload a new flash to the dev board. If I power down the FPGA and power it back up I get the same result. This leads me to believe that its not my reset and its more of a flashing problem. Is there some kind of setting to make the flash stick? or should I go back to debugging. How do you make the flash persistent, I don't see an option for that in the programmer, do you have to configure the user flash?


texts: How to increase polling speed of data from external ADC (controller and ADC has SPI interface) without any external interrupt?

texts:
I have an an external ADC which has capability to sample data at 40Ksps and controller needs to poll the data from ADC. I am unable to get enough sampling rate by keepon calling it from while(1) loop (i.e., nearly 8Ksps I am getting). It has no external pin to notify controller about data ready.

How to make it fast enough to reach upto that sampling rate??
Since I am sampling it at that rate, I need to transfer data on USB simultaneously so, how should I implement the buffering scheme to have minimum delay between consecutive data packet?

FYI:

MY SYSCLK: 168Mhz
SPI Clock: 10.5Mhz
controller: STM32F4


texts: Why is a Current Transformer always connected to ground?

texts: A CT usually has its S1 and S2 terminals connected to an ammeter or transducer for measurement purposes.  However, the S2 terminal is also connected to ground. Why is this so? Why does this not affect the current flowing through the ammeter?


texts: Choosing between active opamp filtering or an LC filter

texts:
This question follows a previous one I asked, where I accidentally achieved undesirable results from an opamp.  Since then I have read up on active opamp filters (here and here) and refreshed my knowledge of LC filters.

My goal is to add some low-pass filtering to the circuit below (features in this question).  The input is from a loop of 24AWG wire approx. 1ft x 4 ft, through a balun then coax.  As well as the 5Mhz signal from my transmitter this understandably picks up a lot of other RF (like the local radio ham on the 2 metre band).

I simulated four different circuits, bode plots below:

The circuit with no filtering (all parts taken out)
Just the 62p/30p capacitors in the feedback loops
Just the LC filter between amplifiers
Both the opamp filtering and LC filter

My question is: Is one of these low pass filtering methods more suitable than the other for real world circuits?

Edit: I opened a specific question for the application here.  However I would still be interested in generic answers to when active opamp filtering is better/worse than an LC filter, if this is a sensible question.

After some experimentation I found the 62p/30p capacitors allow roll-off around 5Mhz.  However these seem like very small capacitors, and I worry that 5% parts leave a lot of room for the -3dB point to shift.

The LC filter was designed with ELSIE, simulation results look good and it rolls off fairly sharply.  However I don't know if it is unwise to use it in this way.

1. Bode plot - no filtering

2. Bode plot - active opamp filter only

3. Bode plot - LC filter only

4. Bode plot - active opamp filtering and LC


texts: What does V(L) stand for in Translators?

texts:
This may be an easy question, but I do not understand why Maxim uses the letter "L" within the second supply voltage for MAX13046E. Other manufacturers like TI and NXP use names such as VCC(A), VCC(B) and Vref1, Vref2 in reference to Translators/Level Shifters.

I've searched Maxims glossary to determine the "L" callout with no luck. I am guessing it represents "Logic," "Level," or something as such.


texts:
I am trying to measure CMRR of an op-amp and I found an application note from Analog Devices, that suggests the circuit below. I understand what CMRR means, but I can't understand why in the formula they use \$V_{IN}\$, although the common mode voltage here is \$V_{IN}\frac{R2}{R1+R2}\$.

When I tried to find the equation myself, I get \$V_{OUT} = V_{IN}\frac{R2}{R1+R2} \frac{1}{CMRR}(1+\frac{R2}{R1})\$

Is the common mode voltage for this amplifier \$V_{IN}\$ or \$V_{IN}\frac{R2}{R1+R2}\$ ?


texts: Are op-amp circuits more noisy than amplifiers built from discrete components and why?

texts:
The reason I wanted to ask this question is because I was designing a project for an electronics course I was taking last semester. The idea was simple. Take input from a microphone and amplify it sufficiently to turn an LED on/off depending on the frequency that was passed. Now, in my research I came across an article that stated OP Amps (unless very expensive) are a source of tremendous electrical noise in their high-gain applications. So, I resolved to a two-stage design with a BJT amplifier (~50 gain) and an OP Amp (~gain 2) for an overall gain of 100 to reduce the alleged noise issues.

So, in short, why do OP Amps have electrical noise issues (if at all), and what is the source? Why are Op Amps more noisy than other types of amplifiers (BJT and MOSFET, for example)?

It seems that any application of amplifiers in general would potentially be a source of 'amplified' noise if there exists such noise in the input signal. Perhaps Op Amps lack sufficient filtering capabilities that are inherent to BJT and MOSFET design? Op Amps are, internally, transistors anyway, so why the noise difference?


texts: What are current PCB surface protection techniques?

texts: What are the different tinning techniques for PCBs, and what are the advantages of one technique over the other?


texts:
I am losing the last bytes into the checksum on my gps unit found here http://www.adafruit.com/products/746. If I comment all lines out except for line 2, then all the bytes are recieved correctly. Is there a way to finish receiving the checksum bytes?

if (mySerial.available()) {
//      Serial.print((char)mySerial.read());
  char c1 = (char)mySerial.read();
  if (c1 == '$') {
    char a = (char)mySerial.read();
    delay(10);
    char b = (char)mySerial.read();
    delay(10);
    char c = (char)mySerial.read();
    delay(10);
    char d = (char)mySerial.read();
    delay(10);
    char e = (char)mySerial.read();
    delay(10);
//        Serial.print(a);
//         Serial.print(b);
//          Serial.print(c);
//           Serial.print(d);
//            Serial.print(e);
    if((a=='G') && (b=='P') && (c=='G') && (d=='G') && (e=='A')) {
//          Serial.println("Match");
    Serial.print(c1);
    Serial.print(a);
     Serial.print(b);
      Serial.print(c);
       Serial.print(d);
        Serial.print(e);
      for(int i = 0; i <= 69; i++) {

          into[i] = (char)mySerial.read();
//              delay(100);

      }
      for(int j = 0; j <= 69; j++) {
         Serial.print(into[j]);
      }
      Serial.println("-");
    }
  }

}


texts: If a crystal has a rated load capacitance of 6 pF, is the right thing to do to put a 6 pF capacitor to GND on either leg of the crystal? I'm using it as the clock source (TOSC) for an XMEGA and it's got a max ESR of 50 kOhm (which is within recommendations).


texts: Logic level converter for H-bridge and UART for Raspberry Pi

texts:
Here is my situation:

I'm using a raspberry Pi to control a H-Bridge. The H-Bridge is not tolerant of both it's inputs being high logic value, which causes a short through the transistors, bypassing the motor. Because the H-bridge requires a 5V input, I slapped together this disaster:

Getting rid of floating input in a logic level converter

Now, as i understand, that circuit sinks current to the RPi, which is not only dangerous, but also crashes the Pi. Not only that, but the RPi boots with the output pins floating, which causes the logic level converter to output 5V, shorting the H-bridge as mentioned.

At, first I got around the issue with having a manual switch disconnect the H-bridge until I could set the RPi pins as outputs, the current sinking was tolerated. Now, I connected UART also through this converter(TX) and a voltage divider(RX) and it just crashes the Pi-s UART, I think it is because the RPi cannot handle sinking that much current. (UART works fine if motors inputs from the RPi are disconnected)

I need a schematic for a 3.3V to 5V logic level converter that acts like this:

1. on floating input, outputs 0V
2. does not sink to input
3. uses PNP and NPN transistors
4. is relatively easy to build

I'm assuming a voltage divider is fine for dropping the RX line from 5 to 3.3


texts:
I'm trying to make a circuit with both a AND gate and XOR gate as outputs. I thought about using a NOT gate, so that the OR gate only functions when AND is off (giving XOR).

I succeeded in making all these 3 gates work separatedly, but when I put them together, it doesn't work.

-If I remove the right parts of the following circuit, the AND works correctly.
-If I remove the AND part, the OR functions correctly as well
-However, if I keep all together, both leds are always turned on.

Then with my multimeter I saw that there was nothing going on from the AND part to the mosfet on the right (so nothing between M1's source and M2's gate). I would have expected to have a voltage diff of 0V between M2's D-S, but I got around 5V, so I can't seem to use it as a NOT to prevent current from going to the OR (XOR)..

I thought about adding resistors around but I really don't know how I can make it work. Would having P type mosfets help ? I'm a bit lost..

Thanks

Edit: Now added a pic showing the voltages I got (Gray: A and B, red: Only A, blue: Only B), with changes suggested by Immibis.

simulate this circuit – Schematic created using CircuitLab


texts: Capacitors and resistors shown as OPEN and SHORT in Schematics design

texts:
I am designing a wireless power Transmitter circuit and mostly following this datasheet for Wireless transmitter IC :-
http://rohmfs.rohm.com/en/products/databook/datasheet/ic/power/switching_regulator_system/bd57020mwv-e.pdf

In the BOM table on Page 28-29, there are several capacitors and resistors which are shown in the Application Example Circuit but in BOM, there are marked as "OPEN" So i was wondering that if this "OPEN" means same as DO NOT MOUNT.
Also the resistor and a common mode choke are marked as "SHORT". Are they shorted? Example:-

Capacitor CCLMP and Resistor RCLMP "open" CAP CCLMP and RES RCLMP

Similarly, ROSC as short and COSC1 COSC2 as open ROSC and COSC1 COSC2


texts: System identification on a non linear system

texts:
I am trying to estimate a transfer function for a pan - tilt unit.

It's input parameter is a velocity, but it is constrained to move from 0∘ - 359∘ and the other way around. Saying in another way, it is not capable of continuously pannning 360∘ . When it hits 359∘ it will not move in same direction, but has to move in the other direction, thereby making it non linear or what?

What kind of test can be performed to identify the system. I know its position and the velocity it moves with at all time. My Idea was to change input direction when the position reaches a limit, but it would just mess up my sine sweep, but that way i won't be able to reach all modes..

The plant has to be used to determine a proper controller for it.


texts: i2s sginals and noise when connecting a 10cm cable

texts:
I have a board that outputs an i2s signal (mclk at 49Mhz) using normal fliflops at output. Works perfectly when connected with short connections.

If I try connecting a cable at 10cm or more, I have some noise comming into the system.

My question is, should I use a buffer after the FFs to correct this ?


texts:
I am reading a datasheet of a motor and I keep seeing wires crossing each other and crossing them again. (see the picture below). Does anyone know what this means?

EDIT:

I also see this picture in this datasheet the following picture (below) which is more like the situation I have. I want to control the motor with my microcontroller. Does this change the situation on the crossed wires in the schematic (So is it now still differential)? And can I just simply control the motor with a transistor as shown in the control block in the schematic?


texts: If light is an EM wave, why don't antennas pick them up?

texts:
Or do they get picked up but don't show on spectrum analyzers? Although the photons in light are greater in energy than radio waves!

Wouldn't there be constant noise from light? Even if it's small.


texts: How to control a Sonoff Basic switch with an Arduino Nano

texts:
My goal is to "switch" a Sonoff Basic (board RF R2 Power) from an Arduino Nano (which is connected to a few sensors). Based on this video, I found which pin to use on the Sonoff. After a test, this is working by connecting KEY and GND very briefly. I used the white cable you can see on this picture. It is always +3.3 V (from KEY) but when you shorten KEY to GROUND for a sec it switches on release.

Now, I am working on how to "replace" the white cable with the Arduino it-self. I used the following diagram with R1 = 50Ω.

Question:

How can I calculate value for R1 because 50 is a guess from what I found over the web.

Problem:

The Sonoff Basic does NOT start if it boots after the Arduino. No green LED. It works fine if the Sonoff boots first, then the Arduino right after.

Any idea what is the cause and how to solve this ?

This is the code I use on the Arduino Nano to test the whole thing. Basically it changes de Sonoff switch position every 4 seconds.

void setup() {
  Serial.begin(9600);
  pinMode(3, OUTPUT); //Pin 3 triggers camera via optop-isolator
  digitalWrite(3, LOW);
}

void loop() {
    delay(3000);
    digitalWrite(3, LOW);
    delay(500);
    digitalWrite(3, HIGH);
}

Thanks for your help !


texts: I am working on an inverter with a battery charger for a 24V,200AH AGM battery pack. The battery charger current can be adjusted from 10 to 50 amps. Now, I want to be able to also a charge a lithium battery (24V,150AH) with this charger. Since the lithium iron phosphate  battery has a BMS along with it which will prevent over charging and over discharging and also controls temperature, I can use a normal charger, right ? without a cell balancing module in the charger as the BMS takes care of it ? I need to only be able to adjust the discharge cut off voltage and charging cut off voltage for the entire 24V battery pack as per the manufacturer's data sheet. The lithium battery I am talking about there is one which has BMS integrated inside the battery pack.


texts: XC8 Pic function ptrs looks optimized away

texts:
The problem is - new_handler in OWT_RegistrateHandler always equals &_DummyHandler and i cant understand why. Im tried to disable optimizations and make all variables volatile for debuging. But nothing helps.

Initialization

    static ptr_v_foo_v  handler;
    static ptr_v_foo_v  dummy_handler_ptr = _DummyHandler;
    static ptr_v_foo_v* handlers_list[MAX_HANDLERS];

    memset(handlers_list, 0, (sizeof(handlers_list[0]) * MAX_HANDLERS));
    handler             = _DummyHandler;
    handlers_list[0]    = &dummy_handler_ptr;

Problem function

    owt_owner OWT_RegistrateHandler(ptr_v_foo_v* new_handler){

    byte i;

    // Search for occurrence
        for(i = 0; i < MAX_HANDLERS; i++){
            if(handlers_list[i] == new_handler){
                return i;
            }
        }
    // Search for free slot
        for(i = 0; i < MAX_HANDLERS; i++){
            if(handlers_list[i] == 0){
                handlers_list[i] = new_handler;
                return i;
            }
        }
        _ThrowError(OWT_ERROR_MAX_CALLERS);
        return 0;
    }

Function call

    claim_index = OWT_RegistrateHandler(&function_pointer);

Functional description: OWT_RegistrateHandler receive address of function pointer and checks handler_list for same address and free space, after, it write argument to the free `hanler_list' index, and returns this index.


texts: Problem with RF circuit using HT12D and HT12E

texts:
I am making a circuit using my RF TX and RX on 315 Mhz, already paired, and I have done the following circuit: powering it with 5V and GND from arduino:

And the picture of the circuit done:

when I power the circuit up, the LED which would be suposed to be on default dont light up.. what may be wrong?


texts: Timer circuit activated by the ignition of a car

texts:
I need to create a timer system with the following characteristics:

The system receives a post-key input signal (12v) from the ignition of a car. When this input signal is recognized the system activates an output and sends (12v). If the post-key input signal (12v) is switched off (0v) the output remains on at (12v) for 10 minutes. If after 10 minutes the input remains off (0v) the system deactivates the output (sends 0v to output). Each time the input is activated (12v) and then deactivated (0v) the system should start counting up to 10 minutes and then turn off the output. If during the countdown the input is activated again the count must stop and wait until the input is deactivated and then start counting again.

I must do this without the use of microcontroller. I have to use integrated circuit timer, does anyone know of any circuit that can help me do that?


texts:
If flash memory is slower than magnetic disk, how can SSDs be faster than magnetic HDDs?

  Flash memory (such as USB thumb drives) is a specific type of EEPROM, used for
  small portable disk drives. The difference is any byte of an EEPROM may be written,
  while flash drives are written by (larger) sectors. This makes flash memory
  faster than EEPROMs, but still slower than magnetic disks. (CISSP study guide by Eric Conrad etc.)


texts:
I have a digital signal called FAULT that is active-low. It will be high 99% of the time and low in rare cases.

I'm trying to use a latch so that the majority of the time the output of my latch will be low but when FAULT goes low, I would like my latch to output high AND stay there even if FAULT goes back high. The only time I want my latch to reset is on a power cycle.

In a nutshell - "Output of my circuit should be low until FAULT goes active (low) at which point output goes high and stays there no matter what until a power cycle"

I came up with this initially (I know it's wrong)

The only issue with this is that it assumes that the initial state would be zero and I can't make that assumption since initial state of a D latch is indeterminate.

I was thinking about using an SR latch instead but again I would need to send a reset signal initially and I don't know what's the industry standard way of sending an initial reset in a circuit. Do any ICs exist that will auto reset my latch on start up?

How should I approach this so that my circuit practically realizable in the simplest fashion possible.


texts: I just read a textbook describing the Earle latch but no truth table was given for this device , does anyone know this truth table. Also the book states that by varying the complementary clocking signals, the device can be made to have other useful features but again no details were given. Does anyone have knowledge of what features the author could be referring to? Thank you!


texts: Is this a practical minimalist 5 V-to-3.3 V circuit?

texts:
I've been whipping out quick-and-dirty USB-to-3.3 V supplies for XBee experiments. All it powers is the XBee (ser 1) and a couple of low intensity LEDs on the DIO lines, with a maximum total drawn current of 50 mA. A simple 2950 LDO, a 1N4148 diode for sanity, and a couple of tantalum capacitors. In most cases I can squeeze everything onto the back of the breakout/mounting PCB of the XBees.

Would this simplistic solution be OK for the simplistic 3.3 V requirement?

(Note: the regulator is a 2950 LDO, not 7833 as Fritzing insists on inserting into the schematic.) Additionally, I also have a 22 pF ceramic capacitor off the VCC of the XBee to ground (but it's not a part of this power circuit).


texts: Is the potentiostat resistor wrong in this PDF?

texts:
I was reading this potentiostat paper: (which was found here)

I was wondering how this I/V current to voltage converter works to the right.  Correct me if I am wrong here.
I am pretty sure it goes like this:
Iwe flows in or out from the virtual GND of the C op-amp, but since no current flow there, it goes from the Rm (28.8MΩ), and creates a voltage difference there, which you can measure at Vout.
I wanted to confirm this so from the Table II, lets take the 26.6uA case:

The voltage across R8:
V=I*R =>
766V is way larger from the 5V Op amp input.
Even if one looks at the graphs, lets take the 3*10^-5[A]:

Again, a really large value.
I am starting to think that the values I find are in millivolts, or the author of the article used a smaller resistor and forgot to change its value on the PDF.


texts: Any way to make rise and fall time shorter for custom square wave generator?

texts:
I'm trying to make a custom square wave generator to drive high-side and low side MOSFETs.
I need a HIGH pulse, then a DEAD time then a LOW pulse. Pulses to be adjustable from 10 microseconds to 1 millisecond.
Initially, I drew two custom PWL to do that, which work perfectly (this is one of them:)
PWL repeat forever(0 0 {RISE} {GATE} {RISE+PULSE} {GATE} {RISE+PULSE+FALL} 0 {2*DEAD+2*RISE+2*PULSE+2*FALL} 0) endrepeat

The problem is when I tried to simulate 1k (or greater) seconds transient, LTSpice gets stuck forever in "Expanding repeating PWL" over the entire timeframe area.
Now I tried different approach to generate squares:

use a sawtooth voltage source
use a b-source as a comparator
or, use some Schmidt triggers with proper thresholds across sawtooth

This is working, but for some reason, both Schmidt and B-Source presents a 1usecond rise/fall on generated square wave. I don't understand where it comes from.
For Schmidt I tried to set Rise/Fall near zero (1 nanosecond) but has no effect, still I measure 1 microsecond on graph.

This is output of Schmidt trigger:

This is output of B-Source, the same story, 1 microsecond rise/fall:

Any clue from where this rise/falltime comes from and how to shorten it?


texts: Measuring current using ACS 712 with NI DAQ 9215

texts:
I am trying to measure current from Ignition coil(12V, 4.5A). i used arduino to measure current. And it worked good. And i connected the ACS712 signal pin to NI DAQ 9215. At zero current the output voltage is 2.5v( ACS offset votlage ) which is showing correct in LABVIEW 2017 . But there is no change in voltage when the ignition coil is turned on.
This is thing i got when i measured the signal from current sensor using oscilloscope.

I found the problem for my question. i placed acs-712 to lower side of MOSFET and measured the signal in oscilloscope. and i got the output signal in LABVIEW also.
But the signal is sill noisy in LABVIEW oscillates  between 2.5 to 4. I think i should filter the signal.


texts:
Setup:
A digital output from a device is connected to an output buffer to drive an optocoupler. If device power is lost the output will go in high-impedance mode.

Problem: I want to make sure that the buffer output is low when device power is lost.
How do I dimension a pulldown resistor for the input of the 74HC244N buffer?


texts: LiFePo4 Battery Cells, minimum and maximum charge?

texts: What are the minimum and maximum voltage levels typically considered for LiFePo4 cells?


texts: Multiple Lamp indicators and LED driving using TPL7407LA simultaneously

texts:
I am using TPL7407LA for driver circuit, it will be getting inputs from pic18f67k40 and driving multiple Lamp indicators(24v) and multiple LED indicators(12v).
My question is : Is it possible to control multiple LEds and lamp indicators simultaneously?


texts: Reading a parameter value of module instance in verilog

texts:
I have an ALU module with a set of parameters used as opcodes.

         parameter ADD=0,
         SUB = 1,
         MUL = 2,
         DIV = 3;

Currently building a testbench for that module, I just want to read these values in the testbench, something like C language alu.ADD .

Is that possible ?


texts: Circuit for Battery powered LED turned on by .15 volts from small wind generator.

texts: Question, How can I turn On an LED powered by 2 AA Batteries Switched on from a low voltage .15v from a small Genorator? When the wind blows The small Generator has a propeller and I would like to send a signal to turn on the The LED that is powered by 2AA batteries. The generator Is not powerful enough to light the LED on it's own for this application. It is a model of a wind turbine for demonstration purpous so it will not produce enough power on its own to light up anything.  Thank you for your help


texts: How is it that by adding more components to a parallel circuit, the current at the root increases with no theoretical limit? Using the water flow analogy, you wouldn't find that the flow could increase up to infinity at the tap (with a constant pressure (voltage) as you create more outlets.


texts: XR2206 Function Generator Kit on LM2917N-14

texts:
Please forgive my bad language.
I am making a vehicle speed indicator with an LM2917N-14 frequency-to-voltage convertor (datasheet). I tried it with a cheap XR2206 function generator and an NE555 variable square wave.
With the NE555, the LM2917 is working properly, the output voltage follows the input frequency (even though 5 V supply NE555).
However, with XR2206 in both sine and square wave there is no DC output on LM2917 even using a 12 V supply for the XR2206.
At first I thought the XR2206 output had to be buffered/amplified before it was fed to the LM2917, but it still didn't work. (I use simple TLC2272 op-amp as a buffer/amplifier.)
The XR2206 itself is normal, has a frequency and DC out of sine and square wave (I measured it with DMM because I don't have an oscilloscope).
My question is why can't the XR2206 drive the LM2917? What should be added so that the XR2206 can drive the LM2917?
I really hope the answers, Thank you .....


texts: Holding Reset State Low longer with hardware 555 Timer

texts:
I have a 555 one shot timer circuit in which the Trigger and Reset pins are tied together in attempt to reset the timer every time the timer is triggered so that the one shot really extends for the designed time after the last signal in a group of signals is received.

The problem I'm having is that the signals are very fast so the rest pin is not held low for long enough to actually reset the timer. Is there any hardware I can add to the circuit to artificially hold the signal low just long enough when the trigger is received to get it to actually reset? I've successfully gotten the reset to work when delaying 5ms on trigger to hold the reset pin low using firmware, but this slows down my signal processing significantly.

Is there anything I can add to the physical circuit which will hold that pin low just a tad longer?


texts: Connect 8pin SPI Screen to esp32 dev board with low profile

texts:
I'm trying to integrate a 2.9in Waveshare epaper into a case with an esp32 dev board.
The screen is driven by an 8 pin SPI interface.
I'm hoping to get them as close to back to back as possible inside of a case, which is yet to be finalised. My issue is how can I connect the screen to the board?
I previously had headers installed on the dev board, this made the width dramatically larger as the header pins extend out from the dev board (the dimension I am minimising).
This leads me to the approach of not wanting to use the SPI lead/header pin connection interface.
How then can I connect the screen board to the dev board?

do I need to design an interface board, which would enable them to sit parallel?
or am I so off target that this is not the intent of a dev board?

Appreciate the feedback. Apologies for my inexperience in this area.


texts: How to remove sensor controller from LED panel

texts:
I have a led panel that is controlled by a touch sensor. Light if off by default, single press turns light on/off, long press changes light brightness.

The touch sensor is connected to 3 pins: GND, VCC, PWM.

How can I remove this touch sensor from circuit so the light is always on and brightness is maximum?


texts:
I am using TL431A for my design. Input side 4.7V below emitter and collector should be short and above 4.7V no output. But in my design it's the opposite. Can anyone suggest how to attain ex cat output.

I have attached my design below.

Required:

4.7 < emitter n collector shd short
4.7 > no output


texts:
I'm having trouble understanding how RFID works on the technical side. I know an RF signal is sent to an antenna, modulated, and then backscattered back to the RFID reader
For example,
Does this ON-OFF Keying system work?

simulate this circuit – Schematic created using CircuitLab
My logic is as follows:
Then antenna receives the RF Signal
The signal is absorbed through ground when the transistor is on and "acting" like a closed switch. This represents a zero.
When the transistor is off, it acts like an open circuit and reflects the RF Signal back to the antenna and the antenna radiates back to the reader. This represents a one.
What I see wrong with this is that the antenna cannot simultaneously transmit and receive the RF signal, or at least to my knowledge it can't.
Another example is this google image I found. How does the antenna receive, modulate, and send back a signal simultaneously. Are there two antennas that are "lumped" as one antenna?


texts: Why do electronics components have maximum voltage and not just maximum current?

texts:
I am trying to figure out how electricity works and I wonder why do electronics components have the maximum voltage limit?

Why does the voltage matter? Isn't it the current that can 'kill' the component?

For example if I have an LED with a maximum voltage of 2V powered by a 5V source.
If I put enough resistance in the circuit - it will effectively lower the current and the LED will be working fine, the voltage would stay the same though.
Which means the LED is working fine beyond the voltage limit.

I would really appreciate if someone could clarify this.


texts:
I am trying to measure the "at rest" characteristics of a piezo disc. The piezo is of inexpensive variety, the type enclosed in a black plastic holder: http://www.sunrom.com/img/p/83/83_0_800.jpg

When I use my oscilloscope to measure the piezo, I attach the osc. ground to the piezo black cable, and the 10X selected probe to the piezo red cable. I am able to view the resulting wave at 50mV divisions on my oscilloscope screen.

I find that the piezo "at rest" produces a wave of about 30mV peak to peak, oscillating about 8.3mV. Does this seem like a typical piezo peak-to-peak ambient "output" voltage?

Also, however, there is approximately a 66Hz wave passing through the output signal. What accounts for this 66Hz wave? Is it the 60Hz hum that is somehow created by my oscilloscope, being connected to mains power?


texts: Circuit that can switch between Vcc and High-Z

texts:
I want to develop a switching circuit (for controlling power, rather than digitial signals) that is able to take an input and switch between Vcc and high impedance, rather than switching between Vcc and GND. An obvious solution would be a relay without a pull-up resistor, but that is far too bulky so I need solid-state component(s). I'm also after rapid switching, so a MOSFET is likely to be the best option.
Just to be clear, I'm after a MOSFET circuit that implements the following truth table:
| In  | Out |
| --- | --- |
|  0  |  1  |
|  1  |  Z  |

or something similar. I'm thinking of just using a single MOSFET (pMOS) placed aboved the output which can connect the output to ground (but any simulations I perform just don't toggle the output). Will this circuit be affected when a load is connected? Or is there a better way to implement this?


texts: impedance matching and impedance briging

texts:
Why in RF receiver we need impedance matching for maximum power transfer but not maximum voltage? And why there is no Impedance matching or Power matching in audio engineering?
Is it depends on the signal frequency to chose impedance matching or impedance bridging?


texts:
I build rotary subwoofers that produce ULF (subsonic) sound levels (youtube) .
The amplifier that I use is 12V 350W and supplies up to 25 amps.

I would like to create a reasonably high quality, strong passive filter that has a cut off frequency of 22 Hz.

I would also like to use nth order because it must have a very steep roll-off, e.g. nothing over 30 Hz max. My only concern is that the roll off will affect frequencies below 20 Hz. Is this possible without having to use digital controllers?


texts: Why are color difference signals transmitted rather than R,G,B signals?

texts: In color television systems back in the early days, people used to transmit color difference signals (Y-R) and (Y-B) along with Y, which is the luminance signal. My question is why are color difference signals transmitted rather than just two of the three R,G,B signals along with Y? What is the need for color difference signals rather than pure RG, GB, or RB?


texts: I have an AC supply that plugs into the wall and outputs 8.4V with three pins (+, -, and ground). I would like to save wires and use a six-wire connector to hook a Serial Bus and the AC supply into the same cable. If I had the four USB lines and the power supply, that would be seven pins, and my connector can only hold six. Can I merge the USB GND line with either the neutral or GND lines of the AC supply? What would the effect be?


texts:
Device: PIC24FJ256GB110
I am not getting the highlighted part.  Why it is "Allowed"?
The reference manual says:

Read-After-Write Dependency Rules
If a working register, Wn, is used as a write operation destination in the current instruction, and the same working register, Wn, being read in the prefetched instruction are the same, the following rules will apply:

If the destination write (current instruction) does not modify the contents of Wn, no stalls will occur; or
If the source read (prefetched instruction) does not calculate an EA using Wn, no stalls will occur.