texts: BQ2002 NiMH Charging Circuit not working

texts:
I have the following charging circuit based on the BQ2002 which will charge a NiMH battery using a 5V micro USB cable. I built the circuit already and noticed that the TIP32C is not getting hot and the circuit is not drawing any current, but its able to charge the battery just fine.

The circuit is supposed to turn off when the thermistor gets too hot.

Are there any major connection issues or are my resistor values wrong?

I would like to draw around 550 mA of current.

Thanks in advance

[![enter image description here][1]][1]

Below is the schematic which I updated
The circuit is working now but not drawing enough current. How do I deliver more current?

[1]: https://i.stack.imgur.com/i5gRU.png


texts:
I'm building "lab" (read: regulated) power supply. I've routed the board and I'm thinking if it has any chance to work. Here are schematics. The board:

My main concerns:

IC3 is ST1S14 - used here as up to 1A buck converter. IC15 is AZ34063 - used as <200mA buck converter. Are these routed like they should be? I've read handful of switch mode converters routing tips, but some of them were contradicting each other like: "keep everything close" and "keep feedback as far from inductor as possible". While both of these seem reasonable, both of them cannot be satisfied at once. I also tried to find reference designs of these ICs, without success. In ST1S14 application schematic (on first page) there is "small signal" ground connected to common point below output capacitor and I tried to implement this in my design. Is it what author of the datasheet meant? Is this done right in my case?
Can proximity of two dc-dc converters cause any trouble? What can I do to minimize to interference if there is any, apart from moving the converters farther apart?
Will converters cause any problems to some other board part?
There are plenty of ground plane discontinuities in the lower part of the board. Can that affect analog circuitry in the upper side?

Also let me know if you see any other flaws.

If this helps I can hapily provide you with whole eagle project.


texts: Can you measure the frequency via interrupts when the pins are used by an encoder? SMT32F4

texts:
In order to calculate the current speed, one option is to read the current position every 20ms. The average speed is position_old minus position_current. This works well if there are many pulses per 20ms but at low speeds, the accuracy drops. Once you get speed=0, then speed=2 and then speed=0 again.

The better approach would be to measure the time between rising flanks. This provides you with the exact time, hence the speed.

But can you have two timers active on the same pins? Then Input Capture would be the way to go.
Can you configure an ISR to fire at the rising flank while the timer is used as encoder? Then I can use the systicks to derive the speed.

I am using TIM5 CH1&2 on PA0&1.

(I could obviously connect the input pin to another MCU pin and do the measurement there but don't like that workaround.)

https://github.com/wernerdaehn/CC3D-CableCam-Controller/blob/master/Implementation.md


texts:
I've the circuit shown below.
It's an integrator, with a diode in parallel to the capacitor, and I'm a little confused.

My questions are:

If I apply at Vin a square wave with an amplitude from -5 V to +5 V, what happens to the voltage on V- node?
With a regular integrator at the output node I should have a triangular wave that goes from 0V to \$ -V_{in} \times \Large \frac{t}{RC} \$, but in this case what I get at the output? Is it a "rectified"square wave?

simulate this circuit – Schematic created using CircuitLab


texts: How can I achieve a third interrupt priority level on 8052?

texts:
Most standard 8052 platforms allow the user to configure interrupts to be of two possible priorities: higher, during which any pending interrupt must wait, and lower, which can be interrupted by the higher level interrupts, but lower level interrupts can wait.

Now, if you have a job to be done within the interrupt that takes some time, isn't absolutely time-critical, and can be interrupted by other interrupts, the usual approach is to drop whatever data the interrupt collected into a buffer, set a flag that there is the handling of a job pending, and then let the main loop reach a check for the flag, and perform that job.

There is, however, a trick that allows to save some time and have the job executed directly from the interrupt vector, but at main loop priority - interruptible by both interrupt levels, essentially creating a third interrupt level, below the two existing levels.

How does one achieve this?


texts:
IO Expander MCP23017 is used to drive ULN2003 which drives 24v relays.

60% PWM power to relays cause them to heat less. As MCP23017 doesn't have PWM output, thought of switching the ULN2003's GND (Pin 8)with a transistor at 1KHz.

Lots of IO expanders are required and the PWM IO Expanders cost almost double than that of MCP23017, have thought of this alternate idea.

Is this a right way? If so, will it cause any damage to ULN23007 in long run?


texts: How to mirror resistor? (use same variable resistance for multiple op-amp gains)

texts:
I want to create parallel op-amp circuits/channels and use the value from a single potentiometer to adjust the gains of each uniformly by making each op-amp see a 'copy' of the resistance to set the feedback gain - the amps in question are TL072's and I'm looking to make at least 4 seperate channels.

Is this possible - do any circuits come to mind?


texts:
Given is 3-to-8 decoder. There is 3 selection lines C, B, A (C=MSB and A=LSB) and one enable input. In total here are 16 adresses.

So first we're going to discuss only EN_A.

How many address ranges are there in which the above address decoder activates the line EN_A?
Can someone explain me how can I see that?
If EN_A active is, what is beginning & ending address? How big is the address range?

Address lines - A15 A14 A13 A12   A11 A10 A9 A8  A7 A6 A5 A4  A3 A2 A1 A0

                           Y3

EN_A - Start Address - 0 1 1 0   0 0 0 0   0 0 0 0   0 0 0 0      -> 6000h

EN_A - End  Address - 0 1 1 1   1 1 1  1    1  1  1  1   1   1  1  1     -> 7FFFh

7FFFh-6000h -> 2^13 = 4kiByte

Is this good?

Also if we have EN_B is this adress going to be calculated the same (if my solution is good) because I'm little bit confused with the enable input of the second decoder?


texts: multiple Open Drain UART over long distance

texts:
I have 9 microcontrollers ATMEGA3208 and I have connected the RX and TX lines of 8 of them in parallel. My configuration is in master-slave. The master microcontroller send data to one of the 8 RX lines but only one of them can respond at a time. The cable length is about 3 to 5 metres between each node.

I have two questions. My test was done with 2 slaves instead of 8. UART at 9600bps.

If I setup the TX lines of the slaves as Open Drain it works fine, but the signal doesn't have steep ramps. I thought this happens due to Pull-up resistors. And I also think that is going to be better with 8 slaves on the bus, right?

Why doesn't that topology work if the TX lines of the slaves are not Open Drain?

I managed to make it work by disabling the transmit of the UART in all of them except one, and it worked fine. I had two slaves, so I disabled the one and left the other. Also I noticed that the edges of the signal was sharper. Why are they sharper in that case?

Regarding resistors: The value of the resistors for both RX and TX lines are 2.7KΩ.
However the Open Drain topology would parallel the internal pull-up resistors. According to the datasheet that resistor is about 20KΩ at minimum. So, using a 2.7KΩ in the output would give us a total resistance of 2.52KΩ (20+2.7)/9. And the Open Drain would make a voltage divider 2.52KΩ + 2.7KΩ (Schematic 2). Which means with 8 slaves and Open Drain topology the signal will not go lower than 1V which is the threshold of the low level. Is that correct?

Wouldn't it be better to disable all the internal pull up resistors and place two (let's say: 4.7KΩ) only at the master side?

Distance: What is the maximum baud rate for such distance? I'm a little worried about the signal integrity. The test was done with 9600bps but I didn't notice any significant difference in 4800bps. The distortion of the signal didn't have a difference.

Voltage values are 3.3V for the UART bus.

Schematic 1. (all resistors are 2.7KΩ)

simulate this circuit – Schematic created using CircuitLab

Schematic 2. (U4, U5, U6, U7, and U8 are omitted for simplicity).

simulate this circuit

EDIT: Thank you all very much about your answers so far. I wanted to point out that this is a question about UART only. I am not looking for alternative solutions. I'm just trying to find some answers about the above implementation.

EDIT2: Thank you very much for your answers! I ended up modifying a little my schematic. I disabled the internal pullup resistors of the microcontrollers and I placed external ones at the master's board. Their value would be around 1 KOhm to 3 KOhm. I have to do some tests more to decide the final value. I also replaced all series resistors with 130 Ohm.

I tested 5 slaves over 20 metre cable (with pullup 3 KOhm and 130 Ohm series resistors) and it worked fine.

Would it be better to add open drain/open collector line drivers on every TX lines?

simulate this circuit


texts: Calculating voltage in a two-loop circuit

texts:
I have come across the following question:

Clearly I3 = I2 + I1, however I am unsure over the voltage of R3. Following from the fact that voltage drops in a closed loop sum to 0, the p.d. across R3 must be 10V, and this is the numerical answer given as the solution. However, I am confused over an alternate approach. The current I1 is equal to 10/30 = 0.333A (using ohm's law), and the current I2 is equal to 12/40 = 0.3A. Hence I3 = 0.6333A. V=IR, so the voltage across R3 equals 19V. What is wrong with this logic? I built the circuit, and found that when the second voltage source, V2, of 12V was added to the circuit, the p.d. across R3 rose by just over a volt. How can this be explained?


texts:
When I write protect a PIC using the config bits, does it prevent all future programming or can I still reprogram the part if I erase it first?  I assume this behavior should be standard across all their products, but if it matters I'm using a PIC18 series micro.  The datasheet only tells me what I can set, not the actual effect of setting the config bits.

Can anyone refer me to a datasheet/errata that speaks to the effect of setting the config bit?


texts: xbp24c don't hear anything from AT86RF233

texts:
I'm using an digi XBPC24CZ7WIT-004-revF to listen to an AT86RF233 ( http://www.microchip.com/wwwproducts/en/AT86RF233 ) but I don't succeed.

I tried with a CC2531 ( http://www.ti.com/tool/CC2531EMK ) in place of the xbp24C and it works "out of the box". Here's a screenshot of some packets.

Using xctu, I set panId to 0xFFFF and scan channels to 1 ( I know these parameters are correct, I can see them in CC2531 GUI ).

I suspect a misconfiguration (I hope it's not an incompatibility).

What else should I do or look out?

Regards
Julien


texts: Help identifying connections on Kyosan KE750 power supply

texts:
I recently picked up a used 12V power supply for dirt cheap.  It is a Kyosan KE750.  I've searched the Internet for a manual, but have not been able to find any.

Yes, I have plugged it in, and it does output the 12VDC.  Even with a small air compressor for a load, it holds the output voltage steady.

What is 'LFG' used for?  The other cables were already installed when I got the power supply.  Hot, neutral and ground are connected on 'L', 'N', and 'FG' respectively.
What is 'PALS'  trimpot on bottom right used for?   The 'volt adj'  is self explanatory, and works fine.  The 'PALS' adjustment is not obvious to me.
As best I can figure out, the cable with plug to the left of AC source, should be for an external AC fan.  Is this correct?  When I got the power supply, it had a 12VDC fan installed on the back.  It was pulling power from OUTPUT.  I don't think that was original.  By the way, that 12VDC fan was dead, so I removed it and will replace.  When I plug the power supply to AC power, and measure with a voltmeter, the black plug reads the same AC voltage as between L-N.
Lastly, what is J1 used for?  The cables were cut as shown when I purchased the power supply.


texts:
I'm trying to figure a circuit design that when it is powered it outputs high. Then, when it get a pulse as input (low or high, I don't mind) it wait some time and then put the output to low.

The reason is I have a board with a processor running Linux . If Linux halting process finishes OK, power is cut with no problem, but what happens when halting never finish?

What I'm thinking is starting a timing with a pulse generated by one GPIO before starting Linux halt, and when this timing finish, power is cut even if halting hasn't completed yet. When Linux halt starts, I can't control GPIOs anymore, so I can't maintain certain voltage level in the GPIO pin, that's why I say I need to start timing with a pulse.

I've tried to figure a circuit using 555 timer, but it outputs high during the timing, but not before starting timing.


texts: How to connect multiple ground pins in a FFC connector

texts:
So I have a bunch of these FFC connectors shown here, and a lot of the middle pins are actually ground pins (highlighted in green). I have a multi-layer board, so I want to route all these grounds to an internal layer. Do I need to run separate tracks from each pin and then use separate vias to go the internal layer? Or I can short them all by running a trace across them and then use a single fat via to go the next layer?

Sorry I'm a complete newbie to PCB design, I don't have much idea about proper routing techniques.


texts: Do SOIC op-amps packages behave differently from DIP?

texts:
I have acquired some mcp-6002 op-amps in a SOIC package instead of the DIP I normally use. I have solder these to a SOIC to DIP "converter" so to fit on the breadboard. If I connect them as I do with the DIP (as simple buffers for testing) they don't seem to work, I tested 4 of these and all of them behave similarly, the upper part of the wave is non-existent and I get a small part from the bottom of the signal. Now I tried to put a voltage divider with half-the supply (because they are single supply) feeding the inverting input and the wave appears but the upper part of the signal is kind of low-pass filtered. So the question is, have I damaged these during soldering to the convertors or they behave differently?

correction: "applied"


texts: Question regarding the trigger circuit for an SCR-based coilgun

texts:
I'm an EE student, trying to design a coilgun project. I have had luck with a basic prototype similar in construction to the one on this site, however with smaller flash capacitors in parallel (total of 600uF). The problem is that, despite including a trigger circuit, I must charge the caps with the coil/scr sub circuit disconnected, then disconnect the charging circuit and plug in the "firing" circuit. Any idea what could be causing this?

Also, I'm curious about the firing circuit in the schematic. What prevents it from frying when the SCR gate is triggered? It seems like a ton of current will be dumped back into that side of the circuit, frying the switch and damaging the 9 V battery at the very least.

Note: I'm using a different SCR to that used by that schematic - I'm using a 2N6509G in a standard to-220 package. He is using a silicon power cube, with 4 of the 5 contacts connected. Perhaps this difference is what protects his trigger circuit? Any help appreciated!


texts:
I've got an LM358 based ground fault detector circuit that I've recently revised, and the revision broke it, so far as I can tell.

To make a long story short(er), what it amounts to is using one of the LM358 stages as a comparator has whacky output levels. There's a 5 volt supply, and the inverting input has a 20k/100k voltage divider, for a fixed .833 volt comparison level. When the non-inverting input is 0 volts, I would expect the output to be 0. In fact, it's 4.32 volts. If I make the non-inverting input rise up above the threshold, it goes up to around 4.5 volts.

Now, the old version of the circuit had a 1N4148 diode on the output with a pull-down resistor to ground after that.

What is the diode and pull-down supposed to achieve? Why isn't an LM358 acting as I expect without it?


texts:
I've been playing around with an idea for a little hand-held gaming device using a Nokia 5110 screen and an ATtiny85.

The ATtiny is programmed using my Genuino UNO as ISP.

I was wondering if it's possible/sensible to include a breakout connector on the attiny pins so I can just plug it in whenever I want to update the code, rather than having to remove it from the gaming device? I'm worried about how signals from the ISP would interfere with the other devices connected?

I used Fritzing for the very first time to create a diagram of what I'm thinking of so far (I've breadboarded parts of it with the UNO instead of the ATtiny, and I haven't actually tested sharing the clock & data pins with the 3 controllers yet! The real thing would have more buttons and LEDs!)


texts: What can be said about the dB attenuation for this ferrite bead from its impedance graph?

texts:
If I use this ferrite bead for a USB cable, what can be said about the noise attenuation for 1 MHz and 10 MHz.

The plot only shows the impedance versus frequency, whereas I would like to see the attenuation roughly for a USB cable's interference. I would like to see how much a 1 MHz and 10 MHz interference would attenuate.

Noise originating from the PC and through USB Hub goes into the System. This happens when a nearby device next to PC is activated like  motor. All I want to suppress and try if I can attenuate the noise coming through earth or mains through USB cable first.


texts: Why do some motors have high rpm while other have low even though having same power consumption

texts: I have seen a 500w motor which run on 1200 rpm but a 300w motor with over 10000rpm . I know using a gearbox can give required rpm or torque and torque is inversely proportion to speed but how can I increase speed and decrease torque keeping watts same. Please explain for dc and bldc motor.


texts:
I'm meeting with problem with flyback power supply.

And this is problems at output:

I read some documents online and i think it's ringing of second winding but i try to place 10uF and 100nF ceramic capacitor front and behind L2 but it's also. Frequency of ringing about 4Mhz. Someone can give me some solutions for this issue. Thanks!

*Update 01/12/2017
This is product:

[![Bot 3D][9]][9]

[![REAL][10]][10]

All of picture was measured at full load.

*Update 01/12/2017 continue...:

*Update 02/12/2017: Maybe i got the source of problem, i try with a isolated AC power supplies and the amplitude of ringing reduced. And i will try more times to give a conclusion. Someone can give me some advice about reducing noise from AC power supply?
* Update 02/12/2017: The issue solved, the cause is common mode (CM) noise, i put a common choke coil and it worked fine. Thank everyone!


texts:
I used this code to generate a 32kHz 50% duty cycle PWM output:
int pwmpin = 3;
void setup()
  TCCR2B = TCCR2B & B11111000 | B00000001;
  pinMode(pwmpin, OUTPUT);
}

void loop() {
  int pwmvalue = 511;
  pwmvalue = map(pwmvalue, 0, 1023, 0, 255);
  analogWrite(pwmpin, pwmvalue);
}

The output signal looks like this (shows 2 signals), why? the oscilloscope is properly calibrated.


texts: Does adding a capacitor with a transformer makes it a LC filter?

texts: when i add a capacitor with a transformer is a LC filter formed? Moreover if it acts as a LC filter then what inductance to be considered for checking the frequency response of this filter, whether i should consider the leakage inductance of the transformer or the inductance of the coils?


texts:
How can I easily find damaged SMD capacitors without removing them from the PCB? I want to repair my laptop's graphics card (ATI Mobility Radeon x300). I have done a visual inspection of the board and I couldn't find any damaged parts on it. I think it might be a capacitor problem. I tried using a digital multimeter to find damaged components but did not find any.
Whenever I take my damaged computer parts to the repair shop, the repair guy easily finds the faulty part with the same multimeter that I have and repairs it in less than 15 minutes but they charge a large fee so I am trying to do it by myself. I am new to SMDs.


texts: Determine the drain current (PMOS-transistor)

texts:
I have the following problem:

Consider the circuit below

These component values are given: \$R_{G2}=1.5\text{M}\Omega\$, \$R_{G1}=1.2\text{M}\Omega\$, \$K=2.3\frac{\text{mA}}{\text{V}^2}\$,\$V_{to}=-1.8\text{V}\$, \$V_{cc}=5\text{V}\$.
What is the drain current, \$i_D\$?

Okay, so my thought of solving this would be the following.
First find the voltage-drop across \$R_{G2}\$ through voltage division.
\$V_{G1}=V_{cc}\times \frac{R_{G2}}{R_{G1}+R_{G2}}=5\text{V}\times\frac{1.5\text{M}\Omega}{2.7\text{M}\Omega} =2.78\text{V}\$
I interpret this as also being the voltage at the gate of the pmos. That results in \$V_{GS}=2.78-5=-2.22\text{V}\$
And I'm stuck here. My next step would be to find \$V_{DS}\$, but I am unsure of how to do so. Can anyone help me?


texts: If you are using peltiers as generators do you get double the voltage if you connect two in series, and double the ampage if you connect two in parallel?


texts:
I have a small SOT-23 (3 pins, transistor-like) device that burned out (shorted between 2 pins). I need to identify it so i can replace it, but i can't find the code at all.
The code is: SE and a simbol like a horizontal "P". Like this image:

Here's a picture of the device, although i don't think it will help much:

I'm not sure if it's a transistor, FET or diode.. It belongs (apparently) to a driver circuit for a P-Channel Power Mosfet, but that's all i can share because the circuit is almost impossible to follow.

Looked the code up on many webpages and can't find anything but a "2SC4703" RF transistor, but it's definetly not one suited for the actual circuit.

Any help would be apreciated.


texts: Is inverting the output of a CMOS network a bad practice?

texts:
I am an Electronics & Comm. Engg. 3rd yr. student and we are learning CMOS logic for the first time this semester under the subject VLSI design.
While designing for the logic equation: \$Y= A + B.C\$, the professor first wrote it as \$\overline{\overline{A+B.C}}\$ , then simplified it by De Morgan's laws and then implemented it with CMOS.

I was wondering if it would be better to implement \$\overline{A+B.C}\$ and then use a CMOS inverter to invert to output since this would need lesser number of gates. When I asked the professor if it can be done that way, he said there won't be any sense in using CMOS if used that way. I didn't understand what this means, and why it cannot be implemented this way.

P.S. I'm new on Stack Exchange. Apologies for any mistakes in my way of putting the question.


texts: Connecting power sources in series or parallel?

texts:
Basic question:

Lets say i have two power sources, one supplying 1V and 100mA, the other supplying 2V and 200mA

What would be the difference if i connected them in series or in parallel?

As far as i know, connecting them in series would add up the voltage to 3V, but what about the current? And if in parallel, the current would add up to 300mA, but what about the voltage?

But im totally not sure, thats why i came here to ask


texts: Do I need to screen audio and microphone signals from each other?

texts:
I'm wiring up a new radio and intercom system on my plane. The installation manual suggests:

  5.10.3 Audio wiring

  For any wires carrying an audio signal, a screened twisted pair should be used
  to avoid any unwanted signals interfering with the radio installation.
  Unscreened wires can act as small antennas and transmissions from other
  avionics on the aircraft could be picked up by the radio and heard as
  interference in the connected headsets. For example, Mode S transponder
  transmissions can be audible as clicking sounds in the headset and cause an
  annoying distraction to the pilot.

  Correctly terminated screened wiring will limit any unwanted transmissions
  being picked up by the radio and should be used on the MIC and PHONE
  lines.

All makes sense, however:

Is it sufficient to combine the headphone and microphone signals into a single screened cable, or should I route two separate cables?


texts: Calculate the average power dissipation in Joules

texts:
I'm self-studying this problem, and it seems that  have a problem solving this.

The only thing I didn't understand is this solution is how to calculate the average power dissipation. It's never mentioned in class and I can't find any formula even to proceed.
I know that:
$$p_{avg} =  \dfrac{V_m \cdot I_m}{2}$$
And I don't see how I can apply this formula to the problem. And I don't think it is helpful anyway since it gives the average power in Watts.
So, how can I calculate the average power dissipation?


texts:
I'm trying to write a program in assembly to toggle the on-board LED of the Arduino MEGA2560.

To do so I just have to indicate the direction of the pin (13 in this case which is PB7) as output and then set that pin as High or Low.

I understand that there are two registers related with this problem. One is the port's direction register (DDRB) and the register for the state of the pins (PORTB.)

I'm trying to understand what number or address those registers have so I can assign values to them in assembly. I went into the C++ library in which those constants are defined (iomxx0.h)
and for example DDRB is defined the following way:

#define DDRB    _SFR_IO8(0x04)
#define DDB7    7
#define DDB6    6
#define DDB5    5
#define DDB4    4
#define DDB3    3
#define DDB2    2
#define DDB1    1
#define DDB0    0

Is the register's address 0x04?

If that is the case, what is _SFR_IO8() doing?


texts: Measuring junction temperature of a diode

texts: I am using Simetrix for my simulations. I want to measure the junction temperature of a diode. I don't know how to do it. I gone through all the tutorials and enough of googling. But I couldn't get it. Can anyone help?


texts: I am looking to change faulty, scratchy Alps potentiometer (RK168 series - 50k ohms) in my amplifier. This is not available easily but 100k is available. Will 100k work the same way as 50k without any loss in sound quality? Kindly let me know. Thanks


texts:
These tp4056 can charge at lithium battery up to 1A.
https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdf

I would like to use them in series but charging each battery separetely because the TP4056 modules cannot be wired in serial due to common ground.

But i've made a schematic and i would like to know if it will work or explode.

Here :

In this circuit each module have a tp4056 chip, a dw01 single cell protection ic and a dual mosfet.

The switch is used for the charge or for out 11.1V so you won't be able to use the +11.1V while charging it and it's a dpst switch so no common ground problem.

Can I wire these modules in series?


texts: Different ringing patterns on flyback output

texts:
A modified version of the PCB that I discussed on this post was implemented. It is still 2-layer with all components on top and the ground on the bottom layer. The transformer windings were directly soldered to holes on the PCB, but the input and output used connecteors. Here is a screenshot of the output voltage waveform (from experiment), before adding any common-mode chokes.

The switching frequency is around 140kHz. My initial questions are:

It is expected that the transformer leakage inductance will resonate with the parasitic capacitance of doide (and MOSFET too?). Is this usually the cause for the two ringings per switching period? Does the EMI play a role here as well. One thing I noticed was that when I press with my hand on the big (variable) resistor load, the peak of the riniging dropped by almost half (which was the moment at which the screenshot was recorded) - so it seems the an alternate impedance path was provided for the noise. Another thing is that the load was connected through really long cables (which we can also fix).
Why is the ringing in the output different at diode turn-on than at didoe turn-off? Mainly, how come the freuqencies seem to be different?

There is a lot of room for improvement here, but at this stage it is just trying to understand what causes what...


texts:
I am trying to design a circuit which has four switches, numbered 1-4 as in the diagram. The circuit should function such that closing switch n turns on light n. However, if k > n and both switches k and n are flipped, only light k should turn on.

I am new to electrical engineering and have used my limited knowledge to design the circuit below, which I believe accomplishes my goal. However, I was wondering if there was a more concise way to accomplish this.

simulate this circuit – Schematic created using CircuitLab

Thanks!


texts: Are there limitations on stacking Boosterpacks for the TI Launchpads?

texts:
I've read many pdf's about the launchpad but one thing is not clear to me yet:

Can any boosterpack be combined with any other boosterpak?
If not, how can I tell which boards might work together?


texts: What are the exact conditions, in terms of graph structure, where KVL can be applied?

texts:
This might be a really dumb question, but ...

My understanding of KVL (Kirchoff Voltage Law) is that when you sum
all voltages around a circuit "loop", then the sum is zero.

Fair enough, but in every textbook I've read so far, I have yet to find
a clean, an more importantly formal definition of what a "loop" is.

Is a "loop" any cycle in the circuit graph ?

For example, in the circuit below, can I apply KVL to the left loop, in spite
of it having a short to ground in the middle ?

Is it correct to write v1 + v2 + v3 + v4 = 0 even when v3 is shorted to
ground ?

simulate this circuit – Schematic created using CircuitLab


texts:
I'm using two ADHV4702-1 high voltage op amps for a project. They are configured as a current sink with a class B output amplifier (with some fixes for the crossover distortion). I already have a +/-12V supply for other parts of the circuit (two lead acid batteries), but I'm not sure how I can generate +/-110 volts for the ADHVs. The maximum current is about 25 to 30mA so it's not a high power application, just high voltage. I thought about using batteries for the 110v rails as well, but that needs a ton of batteries in series which I don't have the space for. I tried looking up boost converters that can generate those voltages but had no luck, just ones with positive output voltage. Can you please help me create a circuit that generates those rails?

Here is the full schematic and simulation for the circuit, although not really that important.


texts: What's the sharpest frequency response for a non-causal low-pass filter whose step response doesn't overshoot?

texts:
Butterworth, Bessel, Chebychev, and sinc low-pass filters are used in various cases where there are different tradeoffs between having a uniformly-decreasing frequency response, a uniform phase response, a steep cutoff, or "brick-wall" response.  I believe all such filters can, in some cases, can have overshoot on their step response, meaning their impulse response is in some places negative.

What would be the optimal frequency response, or what types of frequency responses would be available, in a filter whose only constraint was that the impulse response could not be negative anyplace?  Certainly it's possible to have a low-pass filter meeting such a constraint, since a basic RC filter will do so (though the response of such a filter is a bit crummy).  Would the optimal impulse response be a normal distribution curve, or something else?


texts: Weird rectifier attenuation or bad probing?

texts:
I am looking at a full bridge rectifier from mains voltage, using MD5S-W.
First, I build my circuit for use at 20V AC for safety reasons. I used this adapter:

And this is my circuit:

simulate this circuit – Schematic created using CircuitLab
Now, using my probe at 1x attenuation, I see the output as I expect it to be:

But if I switch my probe at times 10 (x10), the output gets weird, every second 'rectification':

Now, the issue gets worse if I plug the 220Vrms mains, and probe it with x10 at the output of the rectifier, using this circuit:

simulate this circuit
(Larger resistors and I also used resistors on the probe + used the 10x probe attenuation since my oscilloscope/probes are not suitable for >250V use.

I see this:

So every second waveform, instead of just making it look worse, now its gone! It looks like half bridge rectifier.
My question:

Why every second waveform/wave there is this issue with the attenuation, while the 'every first' waveform/wave looks just fine? Its just 50Hz after all, not a couple of Mhz or more.

How could I probe my mains for more reliable results? My oscilloscope and probes:

Oscilloscope rated for:

Probes Rate:


texts: Which are hardware projects management guidelines in your organization

texts: When it comes to plan and execute hardware related projects in your organization, do you follow a specific process flow? (like e.g. requirement definition, design definition, test plan). If so, do you have any recommendation or reference I could use?


texts: Should I use a regulator to improve efficiency or safety

texts:
I am considering a low power design where I do not use a regulator.

The components will operate from 1.9 to 3.7 Volts.
The design is powered from two primary cells(Nominal Voltage: 1.5
Volts each...total 3V)

I have added protection to resolve the concern that the batteries could come charged greater then 1.85 volts pushing me over the 3.7 operating limit.

The ultimate goal is to create a low power design.
Typical consumption is less then 1 mA with burst at 150 mA(once a day)

Should I use a regulator for efficiency, safety, etc...?

I found the following question asked previously, but with no technical answer.
Using a regulator or not?

The batteries combined range "should" be between 3.6V max and 2.4V (flat).

I have read in a few places that efficiency could be gained due to running at a lower voltage. For instance if I bucked the voltage to 2 V and assuming my typical current draw of 1mA 2mW vs 3mW powered directly from the battery. If the buck is 90% efficient then I'll be pulling 2.22mW which "seems" more efficient to me. Note: I am assuming we could get to 90% efficiency, but even 70% efficiency would be acceptable... I'm going off the cuff here... Am I missing something?


texts:
I am new to Electrical Engineering, in fact I'm more of a hardware hacker. But I am wondering how to prototype circuit boards, on something like this:

Photo cropped from this Ebay auction link

I don't know how to use one. So I would appreciate some resources.


texts: How to ensure that the output of an inverter is High while it's input is High-Z

texts:
This design is part of a board that Converts PCIE to USB using a Host Controller.
the host controller has an SPI ROM that I want to be able to flash in in two ways.
one way using the Host Controller itself (Signals: A6...A9) and the other way using external programmer called DEDIPROG (signals A0...A3).
I'm using FSTU3384QSCX bus switch, and I want to pass A0..A4 and A6..A9 according to OE1_bar and OE2_bar, where it's enable is controlled by VCC_DEDIPROG voltage that comes from programmer device that I use.
when VCC_DEDIPROG is High (3.3V) I want the other enable signal VCC_DEDIPROG_BAR to be low which will work fine due to the inverter.
but when we disconnect the programmer from power, VCC_DEDIPROG will be high-Z, and I want the output of the inverter (VCC_DEDIPROG_BAR) to be high.
how do I guarantee that?


texts: How hard is it to reverse-engineer a two-way protocol for a beginner with a logic analyzer?

texts:
I recently bought a Tacx Flow trainer, which has a handlebar computer, with a 6channel RJ-11 cable between the trainer and the handlebar computer. The computer reads pedal frequency, power and speed, and is also able to adjust the trainer's brake -- thus two-way communication.

I have little to no experience in electrical engineering, but I thought I would buy a logic analyzer to see what I could find.

I think I managed to infer the GND and PWR (the computer gets power from this cable), and saw some patterns possibly related to speed and pedal frequency in two of the four lines (the two other lines were regular beats, and irregular, tiny signals).

I could not think of a way to progress further. Is this just impossible for a beginner to do?


texts: GSM SIM900 isn't communicating with the Arduino

texts: When I connect my GSM SIM900 module to the Arduino and insert a SIM card, the Netlight and Status light blink for few seconds and then it stops. I am using 5V 1A to power the GSM and pins D7 and D8 for RX TX. When I connect the GSM without the SIM card it connects and responds to AT in the serial monitor. Is it possible that the GSM needs more power when SIM is inserted? and is it okay if i use higher Voltage to power it? Or is the problem somewhere else?


texts:
I have several layer in my pcb design and some of those layers are unwanted as they seems to conflict with each other when i export gerber file.
How to remove some mechanical layer ?


texts: How is this optoisolator being sensed by an input?

texts:
I'm trying to replace a mains input opto-isolator (pictured below) which is connected to an input on an industrial control board.
I would have though shorting the input would be enough but this is not the case. There is an input LED on the board which changes state however it doesn't activate the desired function in the controller
I don't have access to remove the board so I can't see what kind of input circuit it is - but from the above testing I'm assuming it's an ADC.
The large SMD device on the input can't be a PTC as i've drawn here - I think it would have to be a diode for reverse polarity protection.
The resistor above it is 47R - I'm assuming that this is all that is required to trigger the input. I'm going to purchase a few resistor values to test (i've tested tested down to about 500R with the resistors I have on hand and it hasn't worked)
Is there anything else I'm missing?


texts: USB charger limits: 9 V, 1.7 A but only 5 V, 2 A? Not exactly anti-proportional

texts:
The standard USB charger from the box of a smartphone (model EP-TA20EWE) has the following limitations:

9 V at 1.67 A = about 15 W.
5 V at 2.0 A = 10 W.

Should that charger not be able to reach 3 A at 5 V, which would equal around the same wattage as 9 V, 1.67 A?


texts:
I am brand new with MCU and ADCs and would like to build my own oscilloscope. Right now I can capture signals at full speed (7.2 Msps) with the continuous setting and the DMA writes it directly to memory.
I was wondering if I would like to capture data at the ADC at variable rates (1 Msps, 25Ksps, etc) while the system is running, what ways could I achieve this? I am thinking of making the ADC into single-conversion instead, and just timing it accordingly, while the DMA automatically takes care of the writing. Is there a way where I could keep the ADC at continuous mode while only worrying about writing? Could I even change the ADC register CONT from continous to single and vice-versa while the system is on? Thank you!


texts: Anti-static wrist strap is not electrically conductive?

texts:
I am not an electrical engineer or technician, just a curious DIYer.

I bought an anti-static wrist strap and when I did the circuit continuity test (using a multimeter) between the end alligator clip that is grounded and the metal button that clips onto the strap, it came negative. That is to say that the two ends of the wrist strap assembly do not have the circuit continuity. I am wondering how will it conduct away the static charge if it is not electrically conductive.


texts: Calculating speed of the rotor with slip

texts:
The question i'm having trouble with is:

Calculate the speed of the rotor of a  6 pole induction motor with a slip of 2.2%. The motor is connected to a 230V single-phase supply.

I am familiar with the table below and a certain formulae but i'm doing something incorrect and am confused on how to tackle this question.

Any formulaes or help would be appriciated as I am really stuck


texts: Does it make sense to measure components in-circuit in order to prove non-functioning?

texts:
When an electrical circuit is not working properly does it make sense to use a multimeter to measure/test the individual components in-circuit (without soldering them out), e.g. measure transistor continuity test/ fall of voltages?

I am asking myself an in-circuit measure disturbs the result and may lead to false-positive (or false-negatives).
What are your practical experiences of finding damaged parts/repairing of an electrical component?

I am asking this as an hobbyist with only basic theoretical and practical knowledge - I am trying to repair some devices at my own and like to get more knowledge regarding electrical engineering.


texts: Proper Flyback Current Protection Circuit for Variable Voltage Solenoid Driver

texts:
I am using a darlington buffered op-amp to drive a solenoid motor at variable voltages (for variable speeds of actuation). Here is my circuit as it is now:

I am wondering which of the two flyback diodes (from coil to GND and coil to VCC) are necessary to drain flyback current from the solenoid, or if perhaps a resistor across the solenoid is necessary.

The diode from the op-amp output to the coil is to prevent flyback from interacting with the op-amp output. This one I am certain is necessary from hands-on testing.

Normally I see this as a flyback circuit:

But this is notably different from my case, sense it works by connecting and disconnecting the solenoid from ground, whereas my circuit provides a variable voltage at the input. I am wondering what I need to change in the flyback protection setup to account for this difference. Thanks!


texts: Zero Gate-Voltage Drain Current (IDss) vs Drain Source Voltage (Vds) relation for PMOS

texts:
The Drain to Source leakage current Idss at Zero Gate voltage (Vgs= 0) is normally 1uA(max).
However the relationship (or Graph) with Vds (Drain-source voltage) is not mentioned in Datasheet.
Que:

What is the relationship of Idss vs Vds when Vgs = 0 for PMOS
(P-channel MOSFET)? Linearly/Exponentially descreseing with Vds?
When Vgs=0 and Vds = 5, what will be Idss= ?
When Vgs=0 and Vds = 0, Idss=0?  (Where Vg !=0)
Will Idss decrease if Vgs is made positive e.g. +2V ?

I have attached Datasheet snippet of DMP2005UFG

Thanks


texts: Why Periodic Signals has only integer frequencies but non-periodic does not?

texts:
Why does a periodic signal only has integer frequency values while a non-periodic one has all real numbers as frequency values?

The frequency is just the number of times one full cycle has happened in one single second of time. Then on a periodic signal, why can't there be like for example, 5.3 or 2.486 cycles happening in one second? And for non-periodic, the whole signal comes in a mess(not of a properly sine wave form), there is no one standard cycle to be considered then how could the frequency be calculated in the first place?


texts: How does capacitive sensing relate to the resistance of the object entering the magnetic field?

texts: Example: Setting up a capacitive area and dropping resistors of different sizes into the field, how do they affect the field differently? Are several resistors accumulative? Would i be able to tell from the read out of the sensor which resistor has been dropped?


texts: FPC cable contacts. Bottom vs Top and Bottom

texts:
I would like to design custom FPC cables as extensions of my flex pcb that will connect to this connector of another PCB.

My question is about the Connector/Contact type. In the digikey page it mentions "Contacts, Top and Bottom" compared for example to this connector where it just says "Contacts, Top".

My questions are:

1) what is the difference between the two types?

2) In designing the FPC cable for the first connector according to the datasheet
(see image below) do I assume that the contact between the FPC cable and the connector happens in the top side or the bottom side of the connector? The reason for the question is that it will determine if the FPC cable will be designed in the top or bottom layer of the flex pcb.

Related questions I found where
Need help finding the right FFC connector and
Manufacturing Custom FFC


texts: How to detect a number of frequencies with minimal circuitry?

texts:
I'm working on a project now where my goal is to be able to pick out selected frequencies (between 20Khz and 250Khz) from an input signal and transmit the strength of each of those frequencies to a data visualizer in real time. The frequencies I will create myself and inject into the signal which otherwise has unwanted ambient electrical interference and other noise components. What I'm aiming for is something similar to the graphic equalizer LED bargraphs you would find on an old stereo, but detecting frequencies above the audio range.

Right now I'm working with an ATMEGA328 (arduino) that is running a fixed-point FFT algorithm on the incoming signal and sending the data via an XBee radio to my computer. However, the microprocessor isn't fast enough to be able to analyze for the high frequencies I'm looking to detect..

Does anyone have any advice on how I might do this? Using analog hardware or a dedicated IC perhaps?

Many thank yous!


texts: Analysing an s-domain circuit with multiple sources

texts:
So I am working on the following circuit:

I have already worked my initial conditions and the next step is to perform analysis of the charged up circuit. My charged circuit is shown below:

The charged circuit now has 4 sources. I am confused as to how I can go about analyzing the charged circuit. For some clarity, the dependent current source is 0.9vd and the dependent voltage source is 2it.


texts: VCXO - different voltage tuning mechanism

texts:
I am trying to design a VCXO PCB using CVCO55CC-2328-2536.
In the datasheet it is mentioned that the tuning voltage for this particular VCXO lies between
0.5(Min) - 4.5(Max). As the output frequency of this VCXO is completely dependent on the Tuning voltage, this voltage needs to accurate.
I know voltage divider comes in to every ones mind but what options other than than the voltage divider?
Which kind of circuits/mechanisms can be followed for getting the tuning voltage for various frequency options?


texts: Switching power to a device from a microcontroller

texts:
Situation:

I need to turn off power to a 5V lcd screen hooked to a 3.3V microcontroller when it is off, otherwise the lcd screen pulls power all of the time.

The goal here is for the LCD screen to only be on when a GPIO pin from the microcontroller supplies voltage, so that the LCD screen can only be on when the microcontroller tells it to.

Problem: (all solutions I've tried)

-Using a low side n-channel mofset transistor (my preferred way of switching) isn't possible as some of the gpio pins of the micro controller are being used as drains to ground.

-Using a high side p-channel mofset transistor is not preferred because it would require a constant voltage to keep the lcd screen off.

-Using a high side n-channel mofset transistor, even though it would do the job perfectly, isn't possible (so far) because it would require 7V minimum voltage to the gate to switch the 5V drain-source current when the most this micro controller can put out is 5V, and DC step ups are too large and expensive to do the job and I dont know how to make a boost circuit myself.

-Simply attatching didoes to the gpios so that they can't drain to ground won't work, as they drop the voltage too low for the lcd screen to detect.

Question:

Are there any other ways I can switch a 5V power supply with 3.3V GPIOs on the high side in a simple and compact manner?
If not, how can I boost the 5V to 7V to make the high side NPN possible without using a hefty circuit or premade device?


texts: Using a Force Sensitive Resistor (FSR) as a switch

texts:
I would like to use a FSR as an on/off switch. I want to implement it by using an 8-bit 328p processor (either on an arduino or on an AtMega). Im using a voltage divider between the FSR and a 10K ohm resistor.
The idea is the following: when you finger-tap the FSR the voltage across the 10kohm resistor (in series with the FSR) will increase up to a desired threshold voltage (any number b/w 1v-3v will do it). Once it reaches the right threshold voltage, I want it to set a pin as an output, and be able to turn a tiny dc-motor for x second (or x rotations).

I believe that to read the right threshold voltage I have to start an ADC conversion on the ADC Multiplexer selection register. But I'm confused on how should I implement it.


texts: Why is it only one of four batteries (Li Ion) is drained?

texts:
I have a programmable TV remote control ( a Marantz I've had since 1999 or longer if it matters), it uses 4 AA batteries. I often find (at least when I use Li-Ion, non-rechargeables) that when the batteries die, only one is bad, the other three are strong. They are installed in series. I measure the voltage on each when I install them, there is not a big difference in open circuit voltage (lowest of about 1.65 volts, highest is 1.73 volts). When the batteries die, it is about 1.66 volts for three, and some hundreds of millivolts for the one that is dead. This has happened often enough to make me wonder.

Is the power demand concentrated on one when it starts to fail? Why does just the one get drained?


texts: I am attempting to update the application code on an STM32 chip programatically from another chip.  I have an Intel format hex file generated from the build process and I would like to use the bootloader shipped with the STM32 chip for writing the updated application following AN3155.  My question regards the format of the actual data in the Write Memory Command - should this data be shipped as hex? i.e. when quoting the length - 16 bytes would be shipped as a 32-byte ascii representation?


texts:
I have a DC power source which can provide up to 5V, 50mA (LabJack maximum output current, voltage bus-powered) and I want to power my relay (SDT-S-105LMR2,000) with 5V, 100mA.
I have an option to use NPN transistor with a DC current gain of approximately 2, but the 0.7V voltage drop is not that nice.

First question - Is the circuit logic correct (more attention on the added current booster)?

Second question -  Because I am building 16 channel relay board, is there more convenient option for boosting the current for each of the relay (preferably less components)?

Third question - Will the LabJack supplied power will be a good enough source for 16 relays (working at different times)?

simulate this circuit – Schematic created using CircuitLab


texts: Can a Buck converter operated at 200kHz be used to step down 230V DC input to 5V DC output?

texts: I was wondering whether this type of converter is possible. Any clarification on it will be appreciated. Thanks.


texts: Analyzing resistive circuit with ideal diodes

texts:
The circuit is this:

The diodes are ideal. The solution for this question is D1 OFF and D2 ON, and hence current \$I = 3mA\$.

But when I assume that both D1 and D2 are OFF, I am not able to prove that my assumption is wrong.

How can I analyze the circuit if I assume that both diodes are OFF?


texts: Application to solve for Fourier series coefficients?

texts: Does anyone know a way to solve for Fourier series coefficients using Matlab, WolframAlpha, random web app, etc.? For example if I wanted to solve for and plot the Fourier series coefficients for the function x(t) = cos(100*pi*t) + sin(200*pi*t)? I'm just learning this material in my signals course and looking for a way to check my answers.


texts:
I need basic electronics books  (diodes,transistors,current.. etc) as I am just starting out with electronics and want to have something to read over the holiday.

Any suggestions of good beginners' books?


texts: How to generate different noise in LTspice from run to run

texts:
I'm trying to simulate noise in my circuit, and ideally want to get a histogram of a certain parameter affected by that noise over many runs. However, when I use the white() command in LTspice, or variations of rand(), I get the same result from run-to-run. Is there a way to randomize the seed so that I get different white noise every iteration?

Thanks!


texts:
1) QAM's signal formula is

$$s(t) = I(t)sin(2\pi f t) + Q(t)cos(2\pi f t)$$

The I axis and Q axis are orthogonal to each other, but its angle is 45 degrees, or 30 degrees. At how many degrees does the performance or the evaluation toward noise goes down compared to the orthogonal?

2) 16QAM and 256QAM both exist. Why doesn't 36 QAM exist?


texts: How to find places to add power indicator light in simple DC circuits?

texts:
I build a lot of little hobby circuits and I usually place them inside of some kind of project box. Right now I'm working on the "Atari Punk Consol" by Forrest Mimms. It looks like this:

I tried adding an LED to this circuit coming in from the voltage source but that had some detrimental effects on the sounds that this thing produces.

I like to add power indicator LEDs but I'm not skilled yet at circuit design. I realize every circuit is different, so I'm not asking about where to put it on this circuit specifically, but can someone give me some guidance on how to find good places in my circuits to add a power indicator light? What should I look for and what additional components would I need? Any information pointing me in the right direction is appreciated. Thanks in advance.


texts: Strange footprint labeled PJ## on laptop's motherboard

texts:
Today I came across a picture of a laptop motherboar (below).
I noticed three strange looking small footprints, labelled PJ12, PJ36 and PJ37.
The J may stand for jumper, and on the top left corner there is a PJ8 that appears to be covered with a blob of solder.

If that's the case, why are they using that weird shape?
Two adjacent plain square pads wouldn't also do the job?
Why bother taking so much space?


texts: USB Descriptor: iInterface and iFunction - is there a point?

texts:
In a USB Configuration Descriptor you have the option of providing iFunction and iInterface string descriptor indexes to Function Descriptors and Interface Descriptors respectively.

Is there any point to implementing these descriptors? Adding them, I can see the strings I assign in lsusb -v -d vid:pid for the device, but that is the only place I seem to be able to see them at the moment.

Are these string descriptors used anywhere else? Maybe in another operating system?

Yes, I guess I could get at them with libusb in my own software, but that's besides the point - I'm looking at the OS level - is there anything (besides the odd diagnostic tool) that would make use of them?

BTW: this is for a composite device with a number of interfaces of different types.


texts: Why use difference amplifiers over instrumentation amplifiers?

texts: I know that instrumentation amplifiers are difference amplifiers with buffered inputs, and I understand why one would select an instrumentation amplifier over a difference amplifier circuit. But is the only reason one would use a difference amplifier over an instrumentation amplifier cost, or are there some other good reasons/use cases much better suited to difference amps?


texts: Alternative wireless technology for passive RFID tags

texts:
I am working on a project where I have 3 boxes and a RFID reader (mfrc522) attached at the bottom of each box. I keep my wallet/keys/etc in these boxes and a LCD screen displays what is in each box via reading the rfid tag on the wallet/keys/etc. But sometimes it has trouble detecting my keys which I assume is due to other RFID tags and keys (metal surface) as well as it simply won't detect my phone or other electronic devices. Hence, I am looking for an alternative to RFID that I can use to monitor the stuff in these boxes. I need the tags to be super thin (for RFID I was using RFID sticker)so that I can attach the tags to anything.

PS- This is just for an educational project. I am relatively new to item tracking systems and though of making something simple to learn more about it.


texts: Replacing an old 2 speed rotary cam switch with VFD

texts:
I bought an old drill press tnw super condor 30l but the motor smoked because of the rotary cam switch is broken.
The drill is old and the motor have no motor plate but few engraved numbers 380 and 20 the others can't be read, I can't find the rotary cam switch. The company that made them cannot be found "brevetti ergo italia", it was 500v/5.5hp (that's what i remembered i lost the paper that describe the rotary cam switch technical details, i remember and a number I12.07)  rated rotary cam switch.

So i was thinking if it is possible to replace the rotary cam switch with a VFD. I read on one post that say's using VFD will make the motor give half of its torque, i can live with that as long it works

Edit:
The motor is 2 speed motor


texts:
I recently started a course in applied electronics at my university and the teacher assigned us this problem:

Calculate maximum and minimum delays (tDLH max, min and tDHL max, min) in the connection of two gates with the following electrical parameters:

$$
V_{OL}=0.4V \space V_{OH}=3V \space V_{IL}=1V \space V_{IH}=2V \space C_i=50pF \space R_{OH,OL}=130 \Omega \space R_I=1M \Omega
$$

I understood, from the theory that I have to consider the charging time of the capacitor of the MOS but after that I don't know how to continue and how to find the four times.

I used the two, charging and discharging, capacitor's formulas but I get only two times instead of four


texts:
First time asking a question here, please excuse any failures of etiquette!
I have a number of these 5V fans that I have used for small projects. Fully aware that I might be impacting their longevity, I have run them anywhere from 4V to 8.5V to achieve the desired effect and I have so "go-to" circuits to apply these voltages to them.
I decided that I should have a single go-to circuit that applies the higher voltage of 8.5V and uses this  PWM speed controller to achieve the lower speeds.
However, I found that my fans now only work with a power supply voltage up to 5.5V and abruptly shut off above that -- they behave the same as if I was applying too low of a voltage. In addition, there is effectively no speed regulation. The fan is on at the very top end of the potentiometer (drawing about 220mA) and just suddenly cut off as I turn the knob down once I dip below about 90% of its mechanical range.
I wrote it off to getting faulty speed controllers as a lot of reviewers reported, but on a whim I hooked it up to this 12V fan that I also had around. It works as expected! With the controller turned all the way up (I assume a 100% duty cycle), the fan comes on at 3.5V (drawing 50mA) and works as expected all the way up to 15V (drawing 220mA, I didn't test it above) and at its rated 12V (drawing 170mA @ 100% duty cycle) gives me very smooth linear speed control using about 60% of the range of the knob before cutting off.
Am I missing something about the specifications of these fans that I should be looking for before purchasing them? I was under the impression that all 2-wire fans were largely the same, which is clearly not the case.
Thank you for any guidance!


texts: Connecting luma only output to composite input

texts:
In the course of troubleshooting this problem I reconnected RCA connector connected to the RCA input of my TV to the luma wire of AD725 in hope having precise and beautiful grayscale picture, but got the following instead for white chars on black background:

Interesting that white chars on blue background are displayed excellently (in grayscale), but when black chars on gray background screen flickers heavily at the top 1/3 of the screen.

Color artifacts look too strong for me. of course luma trap does nothing (as datasheets states).

Do I miss something, and pure luma signal from the S-video set of wires gets into chroma band so strongly?

Searched through internet and did not find much info if this connection is correct, and what result I would get (no pics and discussion of related issue).


texts: Is this setup proper to observe the attenuation effect of a common mode choke?

texts:
I'm trying to prepare a setup to see the effect of this torodial ferrite ring.. Even though I still didn't understand what way to wind wires to obtain a common mode choke(I saw differnt ways of winding ways), assuming I achieved it, can I use the following setup to observe the choke's effect on CM interference. I plan to use a function generator to create the CM mode voltage and a scope to observe as shown below where Rg is to limit the current across return wire:

If the model is correct, above shows the Bode plot. Lp and Ls are to model the choke made up of the wires wound around the ferrite ring.

I want to wound wires such that I can obtain a good attenuation for frequencies above 1 MegHz. Since there is nothing written about it in the datasheet I need to experimentally find out how many turns/winds I need.

Is my setup proper for such test to see the effect of the choke? If not what should it look like?

(My aim is to roughly demonstrate the effect not a professional setup)

Edit:

Above shows if I use caps to route CM currents back to the function generator instead of using a common ground.

In simulation above Scope and Scope_GND are exactly the same. So does that mean the potential difference will be zero and I will not see anything on scope regarding the attenuation? (Yes it is balanced but then I won't see any change on scope screen isnt it?)

Edit 2:

How about the following?:


texts:
Possible Duplicate:
  How to become an embedded software developer?

I'm third year undergraduate computer engineering I and I like embedded system I would like to be my specialize in engineering , but I found it a fast topic , so from your experience what is the best practice toward this target and what is the first step or books needed .thanks


texts:
Would you recommend any good book dealing with line codes (i.e. http://en.wikipedia.org/wiki/Line_code).

I mean a book that goes a little bit deeper into properties of each encoding (e.g. spectrum). I believe this topic is discussed in many digital communications text books, but there are too many of them


texts:
I have a guitar amplifier which has a ground wire on its plug:

Like picture above.
On my electric outlet there is no ground wire.
If I plug it into a power strip which has a ground wire and then plug this extension cord into my outlet, is it grounded and safe?
Power strip:

EDIT:
Thanks to everybody for your answers


texts:
Some time ago I've purchased Bestar Acoustic's F-B-P3009EPB-O1LF piezobuzzer, but only now found time to actually test it.
To my understanding, piezobuzzer should just work after voltage (in my case - 12V) is correctly applied, that is, produce tone of several KHz frequency.

At least, this is what my other KPEG272A piezo buzzer does, but with Bestar Acoustic's one I just hear single crackling, as if it were a loudspeaker.

Is my buzzer broken or my application of it is somehow wrong?


texts: Microchip SST26VF064B serial flash communication problem - JEDEC ID wrong

texts:
i'm trying to test SPI communication with Microchip SST26VF064B serial flash, and i have encountered a problem while reading JEDEC ID from the chip. According to datasheet, first three bytes should be 0xBF, 0x26, 0x41/0x42. I get entirely different data: 0x7C, 0x20, 0x7F. The chip seems to respond to read JEDEC ID command 0x9F, but always sends the same unexpected data.

I've tried SPI driver provided with SDK for SOC i am working with, and also simple bit banging SPI - result is the same, so i think that SPI communication works ok. I'm running out of ideas what to try next... Is there any reason i can get this data instead of expected ID?


texts: Supplying an appliance with multiple power supplies

texts:
Can I supply a single appliance using multiple power supplies?

For example if an appliance requires 100 watts of electricity, can I supply it with two power supplies, both of 50 watts?


texts: Measuring frequency of a coin vibration motor

texts:
I'm trying to determine the change in frequency with voltage of a coin vibration motor (https://solarbotics.com/product/vpm2/) using an oscilloscope. So far I have tried two different set ups.
Set up 1:
The coin vibration motor is being powered using a mosfet and an arduino to vary the voltage using PWM. I hooked up two probes to the oscilloscope, one on each of the motor's leads, and subtracted the two signals. The only signal that was picked up was the PWM.
Set up 2:
The coin vibration motor is hooked up to a power supply through a 1 ohm resistor. I used one probe from the oscilloscope to detect the voltage drop across the resistor. This set-up was one I found reading through previous replies to a similar question here. It didn't work, as the oscilloscope only showed what appeared to be noise signals.
I've read through other options such as using an accelerometer. Would something else besides an oscilloscope be a better option? Or is there a way to read the vibration using an oscilloscope and I just haven't got the right set up?


texts: Suitable replacement for 2SC2001 transistor? BC337 doesn't seem suitable

texts:
I have a circuit in which the C2001 (aka 2SC2001) transistor failed after many years.  I Googled about, and tried to replace it with a BC337.  The BC337 got kind of warm, and didn't work.  B, C, and E pins were all in the correct PCB holes, I checked and double-checked, and triple-checked.  The BC337 tested OK with my hFE meter.

So, is there something 'special' about the C2001 trannies?  I have seen them referred to as 'switching' transistors somewhere, I don't know what that specially means.  This is being used in a flyback circuit, which switches at approx ummm 140 kHz or so.

Thanks, any help appreciated!

My previous, sort-of related question is here: What type of voltage booster circuit is this?


texts: How are wires placed inside extending single-wire headphones?

texts:
I'd like to know how wires are placed inside the part that connects left and right ear pieces together that allows them to extend significantly without any problems.

Here's the type of the headphones I'm talking about:


texts:
If I have a 24V source, and then step down the voltage to 5V. Then at this 5V level I draw 1 Amp, what current draw will this be on the 24V source. My gut tells me it's 5V/V24 * 1 Amp mathematically but is this true in real life?
Edit:
DC/DC converter


texts:
I have this code for driving a seven segment display for hex.  From my understanding its logically correct, but when I try and run it on my Nexsys 3 board I never get the correct output, it seems that the segments are almost running together when I run it, (ie. the same thing appears across all or some of them and all of the segment are always at least partially illuminated while the segments pertaining to the correct display just have a higher intensity).

below is my code

    library IEEE;
    use IEEE.STD_LOGIC_1164.ALL;
    use IEEE.STD_LOGIC_unsigned.ALL;

    -- Uncomment the following library declaration if using
    -- arithmetic functions with Signed or Unsigned values
    use IEEE.NUMERIC_STD.ALL;

    -- Uncomment the following library declaration if instantiating
    -- any Xilinx primitives in this code.
    --library UNISIM;
    --use UNISIM.VComponents.all;

    entity SSD_driver is
         Port ( hex0 : in  STD_LOGIC_VECTOR (3 downto 0);
                  hex1 : in  STD_LOGIC_VECTOR (3 downto 0);
                  hex2 : in  STD_LOGIC_VECTOR (3 downto 0);
                  hex3 : in  STD_LOGIC_VECTOR (3 downto 0);
                  clock : in  STD_LOGIC;
                  reset : in  STD_LOGIC;
                  SEG : out  STD_LOGIC_VECTOR (7 downto 0);
                  AN : out  STD_LOGIC_VECTOR (3 downto 0));
    end SSD_driver;

    architecture Behavioral of SSD_driver is
    signal count : std_logic_vector(15 downto 0):=(others=>'0');
    signal mux_sel: std_logic_vector(1 downto 0):=(others=>'0');
    signal mux_out: std_logic_vector(3 downto 0):=(others=>'0');
    signal dec_out: std_logic_vector(3 downto 0):=(others=>'0');
    signal OC: std_logic_vector(3 downto 0):=(others=>'0');
    signal SS_cathode:STD_LOGIC_VECTOR(7 downto 0):=(others=>'0');

    begin
    counter:    process(clock,reset)
                    begin
                        if reset = '1' then
                            count<=(others=>'0');
                        else
                            if rising_edge(clock) then
                                count<=count+1;
                            end if;
                        end if;
                end process counter;
    mux_sel<=count(15 downto 14);

    with mux_sel select
        mux_out<=hex0 when "00",
                    hex1 when "01",
                    hex2 when "10",
                    hex3 when "11",
                    "0000" when others;

    with mux_sel select
        dec_out<="0001" when "00",
                    "0010" when "01",
                    "0100" when "10",
                    "1000" when "11",
                    "0000" when others;

    with mux_out select
        SS_cathode(7 downto 0) <=   x"C0" when "0000", -- 0
                                            x"F9" when "0001", -- 1
                                            x"A4" when "0010", -- 2
                                            x"B0" when "0011", -- 3
                                            x"99" when "0100", -- 4
                                            x"92" when "0101", -- 5
                                            x"82" when "0110", -- 6
                                            x"F8" when "0111", -- 7
                                            x"80" when "1000", -- 8
                                            x"90" when "1001", -- 9
                                            x"88" when "1010", -- a
                                            x"83" when "1011", -- b
                                            x"C6" when "1100", -- c
                                            x"A1" when "1101", -- d
                                            x"86" when "1110", -- e
                                            x"8E" when others; -- f

    SEG<=SS_cathode;
    AN<=not(dec_out);

    end Behavioral;

Any help would be appreciated, thanks in advance!


texts: Groovy i2C/SPI peripherals for education?

texts:
I'm helping someone teach an embedded programming course at my university, and he's starting to cover i2C in class. SPI is next. We're trying to come up with a groovy, easy-to-interface, low-cost i2C/SPI peripheral that we could assign as a class project.

I do a lot of electronics design on the side, so I've had my fair share of interfacing with MEMS/light/temperature sensors, peripheral expanders, drivers, and everything else under the sun. I'm having a hard time coming up with a good project, though, because it seems like everything I can think of is:

Way too complicated (many peripherals tend to have dozens of registers required to get the device working)
Boring (there's nothing to get excited about when you get a temperature or barometric sensor working)
Expensive (we'd like to be able to buy a class set of 35 modules, so keeping things in the $2-5 range would be great!)
Circuit/analog-heavy (Ideally, the peripheral would be breadboardable relatively easily, without too much support circuitry; it needs to be 5V compatible)

What say you, electronics community? Bonus points for coming up with a wacky (yet straightforward) project to actually make use of said sensor.


texts: How should I go about bringing up a prototype crystal oscillator? (+ load capacitor question)

texts:
As part of a project I am working on, I need to bring up a 4060-based 32.768kHz crystal oscillator circuit and ensure it works without breaking crystals or having cold start issues.  I can build a board that has pots on it for adjusting Rs and Rp in the schematic below, but should I just pick load capacitors that match my 12.5pF/1µW 32.768kHz tuning-fork crystal (a rather generic Raltron part, if you're deathly curious), or should I add trimmers for the load capacitors as well?  Should I be focusing on only one resistor, or taking the resistor values as givens, for that matter?
Also, are there other tests I should do during the bring-up process besides making sure it starts up at cold temps and works across the supply voltage range I'm dealing with without drifting excessively or frying crystals with excessive drive?  I don't have an active or other ultra-high-Z probe, either, so processes based on direct crystal-node measurements are not useful for me.

simulate this circuit – Schematic created using CircuitLab
Bonus: the MC14060 datasheet specifies a 20pF and an 82pF load capacitor (as shown in the schematic above) for making the 4060 oscillate with a watch crystal.  Given a 12.5pF watch crystal, though, this seems like an awful lot of load capacitance to me, but my understanding of this sort of thing is somewhat limited.  What's going on with their suggestion here?


texts: How to use multiple terminal surface mount chips in amateur project?

texts:
As you can probably tell from the question I am a beginner in the embedded world. The extent of my experience is some playing around with C and assembly using the Arduino. I'd like to make the jump to the more complex embedded chips that use surface mount device package types rather than through hole device package types. How does one integrate them into an amateur project?

Are there breakout boards or CPU sockets for them? I was particularly thinking about Motorola ColdFire devices or ARM Cortex M3 devices. Apologies for the question but I'm somewhat lost by the vast array of devices on offer and just need a starting point really.


texts: Z(out) for small signal analysis with BJT for unbypassed emitter and r0 in place

texts:
from

this BJT small signal I try to solve Z(out) but I find
RC || (ro + RE)
because Z(out) is calculated with ib = 0 => beta ib = 0
from this link too V(in) was calculated
But the expression for Zo given in the book by Boylestad and Nashelsky is
Zo = RC || [ro + β (ro + re) / (1 + β re / RE)]
Can You explain how to retrieve this ?


texts: Voltage Comparator resulting in low when I would expect high output

texts:
I am playing with Voltage Comparators and finding my results are not as I would expect.

This is my circuit:

simulate this circuit – Schematic created using CircuitLab

I would expect in my circuit that my LED would light, because the voltage across the inverted input 1 - is higher than the voltage at input 1 + - because that is connected to ground.

Obviously my assumptions are either wrong, or my wiring is wrong! Please help!

----------------Attempt 2 -------------------

simulate this circuit

----------------Attempt 3 -------------------

simulate this circuit

In attempt 3 - the LED is lit continuously - irrelevant of the voltage applied at Input 1 -


texts: How to properly use packed 2D arrays as input and outputs of verilog task?

texts:
In a part of my verilog project, I am assigning a data to register M[i] by reading from register N[j]. I have written and simulated the code in verilog without any problem. As this particular pattern is repeated many times in a module, I'd like to convert it into a task.
But I'm getting compilation errors when using a 2D array of registers as input and output of the task. Below is a sample code that illustrates the problem.

`timescale 1 ns/100 ps
module test(clk, rst_n);
    input clk, rst_n;
    reg [1:0] idx1;
    reg [2:0] idx2;
    reg [15:0] M[3:0];
    reg [15:0] N[7:0];

    always @(posedge clk or negedge rst_n) begin
        idx1 <= rst_n ? (idx1 + 1) : 0;
        idx2 <= rst_n ? (idx2 + 1) : 0;
    end

    always @(posedge clk or negedge rst_n) begin
        if(~rst_n) begin : reset_registers
            integer i;
            for(i = 0; i < 4; i = i+1) M[i] = 0;
            for(i = 0; i < 8; i = i+1) N[i] = i;
        end
        else begin
            M[idx1] <= N[idx2];
        end
    end
endmodule

The module compiles and simulates as expected now. I would like to convert the segment M[idx1] <= N[idx2]; to a task. So, the new code using a task is:

`timescale 1 ns/100 ps
module test(clk, rst_n);
    input clk, rst_n;
    reg [1:0] idx1;
    reg [2:0] idx2;
    reg [15:0] M[3:0];
    reg [15:0] N[7:0];

    always @(posedge clk or negedge rst_n) begin
        idx1 <= rst_n ? (idx1 + 1) : 0;
        idx2 <= rst_n ? (idx2 + 1) : 0;
    end

    always @(posedge clk or negedge rst_n) begin
        if(~rst_n) begin : reset_registers
            integer i;
            for(i = 0; i < 4; i = i+1) M[i] = 0;
            for(i = 0; i < 8; i = i+1) N[i] = i;
        end
        else begin
            copy(idx1, idx2, M, N);
        end
    end

    task copy;
        input [1:0] x1;
        input [2:0] x2;
        output reg [15:0] A[3:0];
        input [15:0] B[7:0];
        begin
            A[x1] <= B[x2];
        end
    endtask
endmodule

I am getting the following errors when trying to compile it using modelsim:

# -- Compiling module test
# ** Error: D:\projects\test.v(21): Illegal task output argument.
# ** Error: D:\projects\test.v(21): (vlog-2110) Illegal reference to memory "B".
#
# ** Error: D:\projects\test.v(21): Illegal LHS of assignment.
# ** Error: D:\projects\test.v(21): (vlog-2110) Illegal reference to memory "N".
#
# C:/modeltech64_10.2c/win64/vlog failed.

Can someone please advise how to use the registers properly in a task? Exactly what is making the statements illegal? Is it even possible to something like this using a task, or is there other way around?
Thank you.


texts: Are there link pulses when autonegotiation on ethernet is off (force speed and duplex)?

texts: I read this. Is it correct that there is no link pulse when speed and duplex are forced (autonegotiation turned off)?


texts:
I am using this circuit to detect whether or not electricity is being consumed.
There are two sensor sources (CT1 & CT2 ) where a CT coil will be installed. When electricity passes through that wire then a CT coil produces a corresponding voltage which is given to comparator IC (LM393).
The LM393 compares the input and a logical output is feed to D1. Similarly if electricity passes through AC1 & AC2 then a corresponding logical voltage is generated through Q5 and fed to D4. Using D1 & D4 an OR gate output is generated & passes through the Zener diode. The Zener is used to get lower voltage to the transistor circuit. After  that the Zener output is given to Q1 to get LED status and Q2 to get logical output.
Please guide wherever correction is required in circuit so that it can run for a long time without get faulty.


texts:
I'm using a PNP MOSFET to replace a physical button. When I ground the lead I've attached to bypass the switch, the action I need activates (a notification light comes on - it's the activator button on this barcode scanner), so I know I'm working with the right lead.

In the same test, when I insert a DMM into the loop, I see that when pressed, there's about 60uA going through it.

My circuit is as follows:

simulate this circuit – Schematic created using CircuitLab

The gate voltage goes from 5V to 0V when expected, and when I put a DMM between the drain of the MOSFET and ground, I can see ~55uA when the MOSFET is activated. However - the indicator light doesn't turn on.

Any ideas of what I should look for?

The external input is the circuit described in this question, but with a P channel instead of an N channel, as my sensor output goes high when it needs to be off, and low otherwise.

Here's the mosfet I'm using: http://www.diodes.com/datasheets/ZVP4424A.pdf


texts:
This is my first question of Electrical Engineering SE.

I have the following circuit.

I want to calculate it's transfer function, considering ideal Op amps and circuit elements. I have almost completed the analysis of the circuit. Vb = -Vinput because of R0 = Ro and i know that the second Op Amp U4 acts as a mixer, it will add two signals accordingly (based on superposition theorem). I want to ask one thing that is not clear to me. What is the voltage entering the inverting input of the second Op Amp? Not in numbers, in terms relative to the other voltages we know that are present in the circuit such as Vinput. What is not clear to me is that the capacitor (non polarized) C2 lies between Vin and Va(ground) and therefore it creates a voltage drop (or does it?). Also Va should be zero because of virtual ground of Op Amp U4. Therefore does that mean that the second signal on the inverting input of U4 is Vinput? (never mind the first signal, that one is coming from the first op amp and it's -Vinput*(other stuff)) I'm confused with this. If someone could help me out i would be very grateful. Don't consider values of capacitors or R2, R1. I want to understand the logic behind this particular thing. Thanks in advance!


texts: Should a 555 IC remain powered when a [battery powered] device is turned off?

texts:
I'm fairly new to electronics. I wasn't able to find anything addressing this on the Web but that may be because I don't know the search terms to use.

I'm trying to design a device that contains two 555 timers. When powered on, one timer will be used to generate a repeating beep every 5 seconds and the other will be used to turn the device off after 1 minute. It will be powered by a couple button cells which preferably won't be replaced for the lifetime of the device.

Should the 555s remain powered on (ie voltage applied to Vcc pin) when the device is off? This seems like the obvious choice to save battery, but I'm worried that there will be timing issues if Vcc and the input pulse (to initiate counting) arrive at roughly the same time to the 555. Should I add a delay IC to the input pulse? Or should I use 7555s, which draw less current, and leave them powered on? Are they significantly more expensive? How long could I expect the button cells to last with a 555 vs 7555?


texts:
I am extremely new to electronics and stuff, I was trying to design a water level indicator.

In Proteus, all the LED indications are working perfectly, but for some reason my buzzer won't work.


texts: Is it possible to make a multi-display adapter as an independent project?

texts:
I've been looking at the Matrox DualHead2Go, which is essentially the best/easiest way to go about using dual monitors for a MacBook Pro. Some people suggest using a USB to VGA or HDMI - but obviously that would have terrible performance.

I thought maybe it's a doable project that I could interest some of my EE friends to help me with.

I didn't want to pitch the Idea to them yet - just in case I'd look stupid for suggesting it to them if it's not possible to do as a project.

Anyways, I was just thinking I could ask some of you guys if it's possible to create a way to do dual monitors on a MacBook Pro that would be cheaper than buying one of the Matrox boxes. Is it worth trying?


texts:
I have 2 binary counter 74ls161. The first has an input clock of 80 hz. This circuit should increment by one the second counter when 9 (1001) is detected on first counter and at the same time reset the first one. The second counter should also reset when 8 (1000) is detected, but when I probe the outputs I don't see any waveform on the second counter's outputs which remain at 0 level. The most significant bit of the first counter also remains at 0 level.
Here is the schematics
Also the output of the least significant bit of the first counter
Finally there is the output of the second and third bit of the first counter. Somehow they are identical


texts:
I am creating a HDMI to CSI converter, but i dont know if the wiring is correct and if i need to add any passive component. can you guys help me out?

EasyEDA Project


texts: Connection between 3v3 and 5v I2C without have a reference voltage

texts:
I've two board that must communicate trough I2C BUS. One operates at 3v3 and the other one at 5V. I unfortunately can't use a reliable level shift IC becouse the physical connector on the board share just ground and doesn't provide 5V reference.  This doesn't allow me to use also other methods without the other board reference.

How I can modify my board I2C bus, that operates at 5v, to allow reliable communication with the other board?

I've read about Zener diode with I2C, but comments about this make appear this system not safe.


texts: Use of 230VAC overcurrent protection for 24VDC circuits

texts:
Is it right to use 230VAC overcurrent protection for 24VDC circuits? Why? Why not?
For example: http://www.tme.eu/en/details/a9f05120/circuit-breakers/schneider-electric/

I saw some machines which have this kind of overcurrent protection in 24VDC circuits. I always used dedicated 24VDC protections like https://www.phoenixcontact.com/us/products/3036547 with approperiate fuse.


texts: Is it possible to reconfigure a 48v forklift battery bank temporarily to charge with 24v charger?

texts: I have a charger that I use for my 24 volt forklift and I also have a 48 volt forklift and I don't have a working charger for it.  Is it possible to somehow use the 24 volt charger to charge the 48 volt battery bank? Someone suggested that it would work without making any changes but I tried and after several hours the charger said the charge was compete but the forklift still said the battery was dead.  I don't think the batteries would have gone completely dead, they were just working recently, but I'm aware that the fact that they were totally discharged may have killed them.  But they aren't showing any sign of a charge and I'm hoping to give it another try.  Is there any possibility of reconfiguring the bank into two 24 volt banks temporarily to be charged with the 24 volt charger? Was my friend correct in saying that the 24 volt charger should have charged the 48 volt battery bank with no changes? I suspected that he wasn't but I'm not sure.


texts: Simplifying circuit (Theveninøs theorem)

texts:
I'm trying to simplify the following circuit. In the picture, you can see 4 resistors and a voltage source. There are also two terminals at which I measure the output voltage. I suppose that I can replace these output terminals with a voltmeter since I'm measuring the voltage there.

The question is, how can I join these resistors together? Which ones are in parallel and which ones are in series and why? I get mostly confused by the output terminals. If I remove them, then everything is clear.

Thanks!


texts: Can't find socket for the Google Pixel 3 XL Pressure Sensor/Strain Gauge

texts:
For the past 4 days, I've been trying to locate this socket, but I'm really struggling. This is now my 3rd attempt at getting help, so I would really appreciate someone more technical, that could help locate/identify it. I've tried searching for the numbers/logos, but can't seem to find anything with google/bing.

The information on the front of the sensor reads: "PT052-N-C4-V1 (IDT?) MK 1820 20180227 142", & the back reads: "PT052-N-S8_V1 180228 (IDT?) 1820 MK".

The closest thing I could find on this topic was another question on StackExchange located here. That lead me down a deeper hole, & I think I may be really close, but I'm not sure. These are the two products I've found that look like they would work. AXT514124 | F4S(0.4mm pitch) & Molex 5024261430

The Header has two rows of 7 pins each, for a total of 14 pins. The pin pitch is 0.35mm-0.4mm. I'm fairly confident that it's 0.4mm, but I would like to find both a 0.35mm & a 0.4mm connector, just to make sure one of them works.

This is the part from iFixit It's a Google Pixel 3 XL Left Pressure Sensor.

This is a closeup of the header with a little more information on it. It looks like it says "1b" & "H?5". Not sure if that info is relevant.

This photo is the dimensions of the header. The whole size is 4.75mm x 1.25mm. The negative space inside the header measures in at 3.35mm x 0.8mm.

So after it being pointed out (Thanks, brhans & Dave Tweed) that this is a Hirose header, I've been looking at their lineup & nothing really seems to be matching up all the way. The BM23PF is closest header I could find that somewhat matches my dimensions. I strongly believe this has to be a 0.4mm pin spacing.

This is the BM23PF overplayed onto my header.


texts: Why are there only four passive elements?

texts:
I've read that there are four types of passive elements: resistances, capacitors, inductors and memristors.

The memristor was predicted 30 years before it was produced. But why couldn't you invent other type of passive element? Is there a proof?

The definition I'm using of passive elements is something with no gain, no control and linear.


texts: Atmega-328 as an alternative to the Arduino Uno

texts:
As I am building on, every day I learn something new. Today I learned that I really don't need a full-size Arduino (Uno/Nano.) All I need is an ATmega328(/p) chip microcontroller.
At this point, I started looking up basics like how to program it. I came across this tutorial on youtube which demonstrated it. The guy used this setup to simulate an Arduino UNO.

Note: My eventual goal is to get a custom PCB.
This led me to wonder

Will I have to use this whole setup for the chip (Atmega 328) to work as a replacement for the Arduino?
If the answer to the above question is yes, is there any other version of Arduino which I could/should use instead? I am considering another version of Arduino instead of including the above setup on my custom PCB because having all this on the PCB might add to the complexity of the design and push me to have a multiple layered PCB. If I use an Arduino, its components will in a way be on a different layer.


texts: Interfacing VC0706 with AVR Microcontroller

texts:
I am having trouble interfacing a VC0706 Camera with only an AVR Microcontroller. I am using simple serial communication but the camera does not respond. I tried connecting it with a computer but still no response from the camera.

Moreover I am having difficulty in understanding the following:

In What format will my image be stored in the MCU.
Will ATMEGA32 be sufficient to store one image taken from the camera.


texts:
a thermistor is commonly used in power supplies to limit inrush current. But once the thermistor is heated up the resistance is ideally 0ohms. If i switch the power supply on and off rapidly there will be no inrush current limiting anymore since the thermistor will still be hot and therefore at around 0ohms.
That defeats the purpose of a thermistor. So why is it done like this?


texts:
I am referring to the following AppNote from TI.
What is the purpose of transistors Q3 and Q2? Is it to turn the PFET "hard off" when the controller isn't turning it on?

Thanks
AJ


texts: confusing with tl494 application circuit

texts:
According to tl494 datasheet on application section.
For  buck converter, they use error amplifier with 101x gain to control swithching duty cycle and then for curent limit, they use high gain error amp (70 dB, internal, about 3162x gain) to control current (seem like it shut down immedietly when detected over current). Then I got very confusing

It's look like close-loop propotional control will it got steadt-state error with high load?
can it regurate current as CC?
Why it don't need compensater as shone in Loop Stability Analysis of Voltage Mode Buck Regulator

Note also Designing Switching Voltage Regulators With the TL494 don't mention to compensator at all.


texts: Replacing trim pots with potentiometers?

texts:
I have been looking at and considering building the following circuit from Beavis Audio Research.  Their explanation of the circuit:

  Around 1965, Marshall introduced a few amps built around an 18 Watt
  EL84 powered circuit. While these models were intended for practice,
  the sound was much better than other small amps. Unfortunately, only a
  few hundred of these combos were manufactured over the next three
  years. These rare amps were given the model numbers 1958 for the 2X10"
  combo, 1973 for the 2X12" combo, and 1974 for the 1X12" version.
  After hearing the sound samples there, we decided to give this circuit
  a try as a distortion stompbox with FETs in place of the tubes.  We
  opted to recreate the normal channel. The circuit consists of only one
  preamp stage, a volume and unique tone control setup, the phase
  splitter and a single power stage. There is no negative feedback, so
  distortion will be much easier to achieve. You may notice we used 8k2
  as the value of R17 on the 18watt.com schematic. The reason for this
  is to scale the voltages of the associated JFET to the voltages of the
  amp. We did find that the sound was closer to the amp when we did
  this, instead of arbitrarily choosing a value. Please feel free to
  experiment with this resistor on your own.

In the schematic, there are 2 trim pots...  One for the preamp stage and one for the phase splitter stage.  I understand these are for 'set-and-forget' tuning for the circuit.

My questions are:

Should there be any issues if these trim pots were broken out off the board and replaced with potentiometers to enable adjusting from a front panel ?

What effects and/or sound changes could result from this ?

Thanks in advance for any insight.


texts:
I managed to pick up a few cheap VFDs (Vacuum Fluoro Displays), but the information about them is scarce. What makes matters worse is that I am a post vacuum tube era child, so my knowledge in the area of using and driving vacuum tubes is limited.

The display is labelled Futaba 11-ST-26ZA and a (joke) of a datasheet can be found here: Datasheet

The specifications from the datasheet are:

Ei: 4V

If: 18mA-100mA

Ek: 4.5 VDC

Duty: 1/15

Idigit = 1.3 mA

Vgrid: 12 VDC

Vseg: 12 VDC

So my understanding is that I need to do the following to drive the VFD with a micrcontroller of some sort:

Apply 4V signal between filament +'ve and -'ve terminals, limit the current to 18-100mA with a inline resistor appropriately sized, and use PWM at frequency of 15Hz and duty cycle 1/15. I was planning on switching 4V at required frequency and duty cycle through a MOSFET to the filament.
Apply 12 VDC to each segment I want to turn on (again, for instance via MOSFET switch).
Apply 12 VDC to the grid (digit) I want to turn on, as in 2.

Once I get the VFD working, I can implement multiplexing and driving the segments in the MCU properly.

Questions:
Is my above plan reasonable?
Do I need to somehow limit the current to the grid and to the segments (inline resistor - as with filament) or is this not necessary?

Thanks for feedback in advance!
-Igor


texts: I'm new to this site so sorry if this is not in the right place. I need to design a narrow band 10MHz bandpass filter for an RF application. The -3db bandwidth should be about 10khz or narrower. Do you think it is possible to design and build one that is passive, maybe of seventh order, like a chebychev, I have been trying to design one using a tonne software program called Elsie. Most of you probably wouldn't have heard of it. The problem is that it only goes up to seventh order and I think I need more than a seventh order passive filter to do this, could someone please inform me wether they think it's possible to do this using a seventh order passive filter. With inductors over course that are of reasonable Q values, not with Q's of infinity, etc. if not could some please suggest a good program for designing filters that goes to more than 7th order. Also I would like to do this passively. A this is what I have been trying to do for a while but would it be better it I tried to make an active solution?? I would prefer a passive one however. Any help would be greatly appreciated. Thanks


texts: What equation should I use to calculate inductance of wire coil?

texts:
I've been working on a project recently which requires me to build an inductor, however in my research I found many different equations (with a range of variables used and giving very different results to the same coil specifications) and I was wondering what equation I should use. I have attached some links below to sites with different equations on them.
https://sciencing.com/calculate-inductance-coil-6026538.html
https://www.allaboutcircuits.com/tools/coil-inductance-calculator/
https://en.m.wikipedia.org/wiki/Inductance


texts: How to electronically generate exponentially growing sinusoidal signal

texts:
How can we generate exponentially growing sinusoidal signal (further describes below equation and ) using a simple analogue circuit (e.g. op-amps, transistors, or oscillator)?
Mathematically, \$v(t)=C_0e^{rt}\cos(\frac{2\pi}{T} t ),\$ where \$ r>0,\$ and \$ t<n_0 T\$
or, visually something like this (amplitude can be very small)

I already read this question, but I am looking for generating an oscillating signal.