texts: Easier-to-machine alternative to pogo pins?

texts:
My project has a rectangular 5 x 6 grid, 1mm pitch pin header. Unfortunately, it needs to be cycled by the user over 300 times!

We've looked at pogo pins, because of the high cycle count, but the three moving parts per pin and the tiny size of the precision spring makes pogo pins understandably costly to manufacture!

What are some alternative high-cycle, <= 1mm pitch pin array shapes we can consider? Some ideas:

Micro "flat springs" -- like this, but each .6 mm long:

Contacts independently seated on a springy / cushiony foam.
"Grid of triangles" where each female contact is a set of three soft metal balls forming a triangle whose area is < 1mm sq, and where each male contact is a larget soft metal ball that contacts the center of the triangle -- hopefully touching all three corners of the corresponding female triangle pad.
Some kind of liquid or gel conductive medium between pad array connectors, with some way to insulate adjacent lines.


texts: Strain Gages Measurment Error and Saturation

texts:
I have an experiment composed of 16 strain gages, mounted on a steal beam. The steal beam is horizontally placed under a compression cylinder for a stress test. the test took around two hours to complete and composed of different stages and levels, the maximum load achieved on the was of 160KN. The stress machine is a YLE compression machine with National instruments PXI modules for data acquisition

After retrieving the measurement results, most of the gages have stopped changing in value and become somehow saturated as shown in figure 1
while the remaining strain gages did not preserve a linear variation, the installation used a quarter bridge and the results were calibrated at the start.

The strain gages used in this experiment is the Vishay strain gages general purpose linear module 125BT

http://www.vishaypg.com/doc?11196

So the questions are:
- How did the strain gages get saturated? and how to choose the best strain gage?
-what are the causing errors/noise which can cause such behavior? Does the amplifier gain limits affects the resulting values? if so why didn't it affect all of them?
-what are the most common errors and noise generated when installing and using strain gages (the strain gages where soldered to a 10m shielded cable and connected to the machines inputs)

Thank you


texts: Two-quadrant sinusoidal (3-phase) PWM generation

texts:
I have a true sinusoidal BLDC driver, PWM of which works in Bi-polar, Complementary mode.

I have to make it Uni-polar independent or Bi-polar independent, so the operation to become two-quadrant instead of four-quadrant as it is now.

And just can't understand how to do it in case of sinusoidal drive, where all three phases are permanently "on" with some values.

So it must be something like

but for sinusoidal control and not 6-step like in this example.

Thanks.


texts:
I have been trying to implement an open drain Serial output using a Arduino Nano. In the following example I have used 2 Arduino Nanos (both operating at 5V Vcc), using one Arduino as the transmitter and the other as the reciever.

The Transmitter is programmed to send the following series of bytes:

fe
fe
68
60
39
12
11
81
16
68
c1
1
35
1a
16
fe
fe

The receiver is obviously expected to receive the same. But instead this is what the receiver seems to be receiving:

0
0
9
2
63
3b
77
3f
3a
9
1f
7f
65
39
3a
0
0

The following is the circuit I am using to interface between the two Arduinos:

I apologize if the terminology I have used here isn't totally accurate, since I am only a beginner in the field. Am I missing something in the circuit? Is the N-Channel MOSFET I'm using here appropriate for this application? Any insight would be greatly appreciated, thanks in advance.


texts:
I have started work on a new project of mine of building a simple 8-bit computer. Everything I have put together (clock, registers) has worked so far, until I needed to build RAM. For reference I have been using this site.

First, I'm using the 74LS189AN as a 64-bit random access memory, and I will use two of them to make a total of 16 bytes in my machine. I have hooked up one of the chips with the required 5V power supply and had the address data pins connected to ground along with the four digital inputs. The four outputs were connected to a hex inverter (74LS04) since the output on the 74LS189AN is inverted.

Then, the outputs of the 74LS04 are connected to four LEDs which connect to ground. The last few pins are the select and read/write pins. I connected the select to ground and the R/W pin to either high or low but had it set to low at the moment.

My problem is when I power on the chip as soon as I remove the R/W wire to Low then back to high the LEDs just keep on HIGH even though the digital inputs are LOW. After a few minutes, the chip itself begins to heat up so badly that it burns at the touch. What could be the problem; defective chip or am I reading the pin-out wrong?


texts:
Does anyone have chart(s) for Mullard "tropical fish" capacitors?

I have a chart for the 5 color polyester parts but there may be 4 color parts out there.  Plus, I have seen what seems to be 6 color parts.  Any help would be welcome.

There also may have been a later system for non-polyester capacitors like polypropylene.


texts:
I'm designing a resistance measurement device using an LT3092 current source. I've used a DIP switch to select different current ranges, which switches in different sense resistors.

The LT3092 uses a 10uA reference to set the output current, and the datasheet recommends a guard ring (tied to the output pin) around the set pin, on all board layers. This gives me two issues:

The DIP switch means that there's more traces than usual connected to the set pin, meaning the guard ring has to be large.
The set pin (5) and power in (+24V, pins 7,8) are next to each other, separated by an NC pin (6). This leaves the power pins inside the guard ring, which seems less than ideal.

I've attached screenshots of the PCB layout and render (for context). What's the best way to proceed here? Thanks!


texts: Developing PCB for STM32F765 with 16 MHz crystal oscillator, ground plane isolation and 3.3 V plane

texts:
I have developed a PCB in Kicad for the STM32F765 microcontroller. I am using a 16 MHz crystal oscillator for the application. But I am having some confusion regarding the GND and 3.3 plane.

As shown in the image, there is a 16Mhz crystal. I want to make a 2-layer PCB since the budget is very tight.
And for the first layer, which is red if I do ground isolation.
Can I make the second whole plane 3V3, even under the crystal? or I have to avoid a 3V3 plane going under the crystal.
Thank you. I don't know how to achieve this.


texts: Is a transfer function with a denominator of one with V_o/V_i as the definition of the function?

texts:
I've been given this question for my electronics course and have gone through it. The question asks we construct a circuit with transfer function: $$G(\omega) = 11 + j\omega 330 \times 10^{-6}$$The only way I can think this question has a solution is if a current source is used as opposed to a voltage source when you take the voltage over the output.

The answers to it say a the circuit should be a RC LPF with: $$R=33k\Omega \\C=10nF$$So I went through, drew this circuit and derived the transfer function but I can't find anyway that this configuration could have the aforementioned transfer function. Is there something I'm missing in this?


texts: Incorrect output from the voltage regulator

texts:
Hello,
I have a circuit that I designed myself. In summary, I feed the circuit with 2 CR2032 type batteries and try to get 3.3 V output from the LD1117 type regulator. However, I get 4.7 V output from the regulator. I also observe a drop in battery voltage, interestingly when I feed it on battery.
By voltage drop, I mean it happens instantaneously, maybe it would be more correct to specify it as voltage loss.
Let me share with you the situations I have examined.
There was no change of state when I first connected parallel capacitors to the circuit. edit: I mean 10uf and 100nF(capacitors on the datasheet)
I tested the battery packs and batteries also out of circuit. There is no problem with them either.
When I set the same regulator up to the bluepill supply in the breadbord and tried to supply it without capacitor, I got a constant 3.3V output. However, when I supply the circuit with DC supply 6V from the outside, I constantly get 4.7V from the regulator output. And when I feed it with the battery, it initially comes to 4.7 in the same way, then the voltage of the batteries starts to decrease in a short time. When I deactivate, their voltage comes back to 3V.
I haven't had the opportunity to test it yet, but I'm thinking about the question of whether reverse current is coming from somewhere. Do you think putting a diode on the regulator output can solve it? I am open to your suggestions, thanks in advance.


texts: resistor drift via temp messing with ADC readings in voltage divider

texts:
I am voltage dividing 0 to 64 VDC down to 0 to 1.8 volts via a simple voltage divider.

I am using 1% resistors.

The problem is that the readings from the ADC in my beaglebone black seems to be drifting over time in that say 48 volts is not consistently reported as the same ADC reading day to day.

The attached chart shows the drift.  Each day should look identical and does via a Fluke meter.

My circuit is

Vin -> 4700ohm -> 120ohm -> gnd

The ADC sense pin attaches between the 4700ohm and the 120ohm resistors.  The ADC reference gnd is attached to gnd.

The +5vdc  power supply that supplies the microprocessor and ADC is isolated from the above circuit except for a common gnd.

Should I expect so much drift via the voltage divider (presumedly due to temperature)?


texts: Schmitt trigger issues... lumpy outputs and wrong switching voltages

texts:
I'm trying to implement the Schmitt trigger found in "CMOS" by J. Baker. Here's what the circuit should look like:

And this is how the transistors should be dimensioned to achieve switching voltages of 0.7V and 0.4V:

And here's what the output should look like:

This is what my circuit and simulation results look like:

As you can see, my Schmitt trigger doesn't switch at the correct voltages and the output is all lumpy.

In terms of troubleshooting, I have double-checked the connections and transistor dimensions. Also, I played around with the voltage source Vdc to see if I needed a larger voltage. Adjusting the voltage higher than 1Vdc breaks the circuit entirely.

Where have I gone wrong?


texts: Correct way to calibrate SDR RX into a measuring receiver

texts:
While playing with my SDR (Software Defined Radio) Board, I was interested in performing a TX output power table at different center frequencies and TX antenna gains.

However, unfortunately, I do not have a spectrum analyzer for direct TX power measurements, but I do have an RF frequency generator. Therefore, my intentions are to generate signals with well known RF power and measure them with the RX of the SDR, somehow converting it into a calibrated measuring receiver. From this, I would just repeat the setup but now with a direct TX-RX connection. This way, I would know what power I'm transmitting with TX as well.

The problem is that I'm not really sure what should be the quantities that I measure in RX in order to make it into a measuring receiver and I don't know what the digital words measured in RX correspond to voltage neither. Also, I have to assume that RX does not have a 50 ohm impedance neither does TX. Therefore, I can't just convert the power from the 50 ohm frequency generator into Vpk and then use this result to calculate the digital Vpk of the IQ data in RX, since there would be a reflection in the wave and the result would be wrong... right? Or is there a way to measure the impedance of the RX (and then of the TX)?

Can someone please clarify me the methods? I'm not familiar with RF at all.

Thanks in advance!


texts:
No heat from nichrome wire. I have tried various experiments on YouTube regarding foam cutters using nichrome wire or steel wire with 9V batteries with an on/off switch or no on/off switch.

When the steel wire didn't work, I tried using N80 30AWG nichrome wire. I connected the wires from the battery directly to the nichrome wire and no heat at all. I even tried connecting two 9V batteries. I only have a basic understanding of electricity but the simple DIY foam cutters on YouTube do not seem to be much of a challenge to create. Appreciate any help or other tests I can perform to confirm I am getting heat. Oh and the batteries are fully charged.


texts: Multi-Port RAM (1 write port, many read ports)

texts:
I have a project where I may need a 128 KB lookup RAM. I have 1 write port which writes the lookup values at the start of the application. I will have more than 2 read ports (I am assuming 4). I do not want to replicate the 128 KB RAM 4 times for the sake of space.

I wanted to know if it is possible to build a multiport RAM using Xilinx BRAMs by simply adding n RdAddr/RdDataOut ports ? Is this possible. What do I need to take care of when I try to do this ?

Is there an open-source project which has done this, so I dont have to reinvent the wheel ?

Thanks for your info.

RRS


texts: Microcontroller output pin to pull 12 volt signal low

texts:
I am working on a project at the moment which requires a microcontroller to pull a signal low for two seconds. This signal is from a break away board which will be connected to the microcontroller by a screw connector. I am using a PIC microcontroller (18f25k22) running at 5 volts. The break away runs on 12 volts and has a pull up resistor on the signal input. I have built a circuit using two transistors to control the 12 volt signal, but I don't know if setting the pin low on the microcontroller will pull the signal low on the break away board.

The driver circuit:

This circuit is on the pcb containing the MCU. Point E goes to a connector which is used to connect to the break away board. Point RC4 is connected to the MCU pin. My idea was to hold the circuit high until I needed to pull it low, in which case I would set the pin low to turn off the transistors and cut power. The MCU circuit and the break away share a common ground and the whole thing is powered by 12VDC. I have a voltage regulator to power the MCU.

So I ask; will this work and pull the output low? Or is there a better way to do it?


texts: Strange minimalist power supply, which IC?

texts:
I encountered this little gadget, wall-pluggable, and I opened it, I don't even know what is supposed to do! I can vaguely remember it being some kind of "anti-mosquito" thing.
I managed to work out a little handmade schematic, please see attached pics.
I can see kind of a snubber network but are all the expected components there? I have the feeling, that is not a very adequate nor complete design.
Also what could be the marking of the IC an its type? (Scraped off, like most chinese manufacturers seem to do nowadays).
And that strange, 2-pin only "Transformer" or "inductor"-like thing. I can't figure out.


texts: I’m using an STM32 Nucleo board connected to a Raspberry Pi. To flash the MCU I drop a binary file to a mounted drive. The problem is that it takes a random, and sometimes long time, from the moment I drop the file to the actual moment the MCU is flashed. As a contrast, I have an instantaneous result when flashing from Windows. Is there a way to expedite the process?


texts:
I'm a noob just getting my feet wet in EE, so go easy on me, please.  I bought an Arduino Uno and have been learning tons in the last couple weeks.  I took an LM35 sensor, a generic thermistor (using a 10kohm resistor), a light-dependent resistor (photoresistor?) (using a 10k resistor), a button (using internal Arduino pullup resistor), and a couple LEDs (with 220ohm resistors), and wired them all to my Uno.  I can provide a diagram, but I don't suspect that it matters much.  Basically, some are sharing the same ground, and some are sharing the same 5v.

I'm noticing that the temperature data from the LM35 and the thermistor is very erratic. It varies all by itself, plus when I press the button.  I've read many forum posts saying that these types of sensors need a voltage regulator to be accurate, so here's my question: Is it probable that the cause of my erratic sensor data is because the supply from my Arduino is not constant enough, and that it's sagging or spiking?

If so (or if not), what's the solution to this problem?  Should I buy one of those little 5v bread-board power supplies?

Update:
Ok, here's a diagram. It's a proud day for me, this is my first circuit schematic ever!

And here's a graph of the LM35 readings.  It's only read once every 9 seconds.  It's just sitting on my office desk, no furnace vent nearby or anything.  Now, the graph is not raw analog readings, but rather F temperature.  But the raw analog readings are all over the map, including 116, 107, 90, 145, 129, etc.  Don't get distracted by the analog->temperature math, I don't care about the accuracy, I just want it to be stable!

Update 2:
The photoresistor and the thermistor are reading very consistent, only the LM35 is all over the map.


texts: Are there any "general purpose" or "experimental" radio frequencies?

texts: If I were to develop my own radio device, what frequency(s) would I need to use? I can't just use any old one because they are allocated by the FCC.


texts: Is there any reason nowadays to use a neon indicator lamp instead of an LED?

texts:
I have a bunch of old neon indicator lamps recovered from old AC devices and used to indicate power status.

I wonder: is there any reason nowadays to use the neon lamps instead of LEDs? I see they are still widely available.

LEDs are cheaper even after considering the need for a diode in AC applications. They blink half as often in AC applications, but emit much more light per watt.

In what cases are neon indicator lamps still preferred?


texts: What is the type of chip commonly used in android device as internal memory? Where the operating system resides, and often show up as sdcard0 (correct me if I'm wrong)?


texts: How do I wire an op amp to measure the difference between two solar panels?

texts:
I've been trying to hook up two solar panels as the inputs to an op amp LM741. My goal is to have the output be positive and saturated when solar panel #1 has light shined on it and the other doesn't. Then I want the output to be negative and saturated when the light is on solar panel #2 and not the first. I'm having trouble figuring out how to properly wire the circuit. Also, I've been using two 9 Volt batteries for my positive and negative power supply and where they meet as ground.

The voltage of each solar panel is 3V and I'm not clear on how to wire them correctly to compare their outputs using an op amp. Can you please explain in detail where the positive and negative leads of the solar panels should go for an LM741 with two 9 Volts batteries for the power supply.


texts:
I am working in a control project in which I need to control two variables \$x\$
and \$y\$ according to their reference values.

Since I don't have an advanced knowledge in modern control theory, I usually
tackle these problems using PI, PID, lead/lag controllers.

I have simplified my problem in the following image. My system has a matrix with
time varying coefficients (and it adds coupling to the variables), and I am not
being able to write the open-loop transfer function to find the good parameters
of my PI controllers.

Do I need to use a fancier control structure than PI control or can I obtain an
approximation of the transfer function and keep the topology of this solution?


texts: How to calculate voltage divider time constant?

texts:
A cheap and easy way of interfacing a 5V device with a 3.3V device is to use a simple voltage divider.

I've read using a voltage divider to convert a fast-changing signal (such as serial lines) can result in signal distortion due to the RC filter the voltage divider creates.

How do you  determine at what speed the signal will be distorted?


texts: I was wondering about these transformers. It says it requires a DC input (I think) however don't transformers need an AC input, and if so does that mean I would need to make an oscillator circuit to pulse the DC? Or can I just input AC?


texts: Sensors to detect high speed object crossing plane

texts:
I'm looking to detect a somewhat small (5-20mm) high speed (600m/s) object crossing a stationary 0.5m x 0.5m plane.  When the object crosses the plane, I want to know the X, Y.

I apologize for the very broad nature, but I'm just trying to figure out what kind of sensors could be used to construct such a device.  I plan on using the arduino for processing, but am clueless wrt sensors. (I'm really a software guy - dont kill me!)

Thanks,
Chris


texts:
With the MMA8452, it claims that it draws 44uA when ODR = 100Hz in Normal Mode.

However, I'm measuring 1.5mA when ODR = 100Hz. Does anyone know how this could be the case? In Low Power Mode, I'm getting almost identical values. I get even higher values in High Resolution mode.

I'm using a 100R shunt and I'm getting the same values with a scope and with a DMM. I'm using a GY-45, but the I2C pull-ups wouldn't draw that much more current - right?

Any help will be appreciated.

UPDATE 1:

Here's the circuit for GY-45

I'm tried powering it by using the VCC_IN power line with 3.3V and VCC_3.3V with 3.3V. Same measurements.

I did some more measurements. The Vds across the NFETs are around 0.12V. The voltage across the two left 4.7K are around 0.08V and the voltage across the two right 4.7K are around 0.02V. Do these figure help an explanation?

UPDATE 2:

I've desoldered the LDO and have supplied 3.3V and 5V to Vin, but same measurements.


texts: Off load voltage in npn transistor as a switch

texts: There is transistor tutorial on sparkfun.com (https://learn.sparkfun.com/tutorials/transistors/all). I am wondering why there is 1.3 V drop depicted across the LED1 on the picture, since when the base is low (open switch) the collector's current is 0 (almost, 50nA or similar), and it is correctly depicted (0mA). Where does the 1.3V drop come from? Shouldn't it be 0 and 3.7V drop be 5V?


texts: What are the values of these resistors (R17 and R26) in this schematic? Or are they potentiometers?

texts:
Pin 3
Mode Setting. This is a digital input used to determine if the program will enter normal mode or the test mode. The line is read after power up, and the code runs the
mode that is selected. High=normal mode, Low=test mode.

Pin 4
Sample Rate Selection. This is a digital input used to determine whether the sample rate should be 11025 Hz or 8000 Hz. High=, Low=. This setting only has an effect
during normal operating mode, and it can be changed at any time during operation.


texts:
I'm trying to make a pair of devices which can measure their distance from each other (within 50 ft., irrespective of orientation). The basics of a robust solution are described in this comment, but I don't know what components are needed to realize it. Solution paraphrased below:

  The master device emits a radio signal at \$f\$ Hz. The slave device detects the master's signal and produces an \$f\$ Hz signal which is phase-locked with it. The master determines the phase shift \$\phi\$ between its own signal and the slave's signal to determine the distance of the slave.

Since the total phase shift \$\phi\$ depends on the round-trip time, the distance between master and host can be computed, so long as the phase shift is less than \$2\pi\$within 50 ft.
$$
D = \frac{C}{4 \pi f}\phi
$$

It seems \$f\$ = 10 MHz would be the best frequency since the half-wavelength is ~50 ft.

How does one realize the signal transmission, detection, phase-locking, and phase shift computation. I'm good with embedded systems, but know very little about producing or detecting radio signals. I assume there will be VCOs, PLLs, amplifiers, and antennas.

Also how can the master distinguish between its own signal and the slave's return signal, when determining the phase shift?


texts:
If voltage is measured relative to something. For instance, voltage-meters measure voltage differences not individual voltage levels, or by analogy altitude is measured relative to somewhere. Mount Everest is so-and-so compared to sea level. But zero compared to itself.

How come line to line voltage is not zero when both lines have the same value? For instance, a three phase three wire Y connection of 120V with an angle of 120 degrees. Line to line voltage here is $$120V \times \sqrt[]{3} \approx 208V$$ not zero.


texts: how to make thin-traces handle high current

texts:
According to The Circuit Calculator my 18 amp traces on 4 oz copper need to be about 160 mils. Only problem is I don't have room for this.

I've seen boards use raised bus bar and also solder bus bar directly to the trace to increase current capability. Has anyone tried this? Is there any major issues with doing something like this? Also what type of metal should I use for the bus bar??


texts: Combined ADC scaling and offset with variable input voltage ranges

texts:
I am trying to create a circuit which will allow me to scale and offset a voltage (be it AC or DC) to within the range of the Arduino ADC.

The voltage could be anything between + and - 250V, but I also need to have good sensitivity over lower voltage ranges too.

To this end I am looking at a circuit whereby you can vary the voltage range that it expects the input to be and amplify/attenuate it accordingly.  How I will be making the decision and setting the different gains is for another topic for now.  I am only interested in the scaling and offsetting at the moment.

So far I have come up with this circuit:

Which appears to do just what I want for the +/- 250V range.  I don't know how "safe" this circuit is, and if I am endangering any of the components with the 250V or not.  The graphs at the bottom are (left to right) the input voltage, the power consumption of the bottom 10M resistor, the voltage across the 100M resistor (which is simulating the Arduino ADC input) and the power consumption of the upper 10M resistor.

Now, if I drop the input voltage to just +/- 2.5V and tweak the op-amp feedback resistor accordingly, for some reason the offset voltage the op-amp is adding jumps right up.  I don't know for sure if this is the fault of the simulator I am using, or if it is really what will happen, as I haven't yet breadboarded this circuit (I guess that's the next stage).

This is the output from the 2.5V version:

You can see how the offset has jumped up and the output is clipping massively.

If I drop the lower 10K resistor to the virtual ground offset voltage divider to just 3.3K it compensates, but that's not nice - I would like to just vary the one resistor.

The op-amp is (will be) a 5V single supply rail-to-rail I/O one.

The two diodes are to protect the input of the op-amp against over voltage - I don't know if this circuit strictly needs them, but I guess it doesn't hurt to have them there.

Also, I don't know if the resistor values are quite what I want - I chose them to keep the power consumption right down and the impedance right up.  I don't want them to impact the frequency response of the circuit more than I can help - the input waveform could be anything from DC up to around 500KHz or so, and I need that reproducing at the ADC end as faithfully as I can.  (I know the Arduino can only really sample at lower speeds than that, but the Arduino is just for experimenting - the final system will use a dsPIC with 1.1Msps ADC).

So, what can I do to A) get a more stable offset, B) allow the varying of the input sensitivity without nuking either the op-amp or the ADC, and C) make the circuit safe to connect to, for example, a European mains voltage?


texts: can i use 4 3v coin battery for a 12v grain of wheat led bulbs

texts:
I have 12v mini grain of wheat LED bulbs I want to use for street lights in my miniature Village of Wonder.  Because of the size of the street light the coin battery CR2032 3v is the right size.  The mAH is 220.  4 of these batteries would be 12v. Does this sound like it would work.  If not what battery would work?
I have the bulbs and would like to use them,  with batteries instead of electricity.
Thank You,
CjJehn


texts: Why is the gradient of Energy vs. wavenumber(k) zero at the edge of Brillouin zones?

texts:
My question relates to semiconductor physics. The relationship between energy E and wavenumber k for the Kronig-Penny model looks like this, where a is the period of the potential function:

I am referring to a statement made in the book Advanced Semiconductor Fundamentals, 2nd Edition by Robert F. Pierret, page 61. In reference to the E-k diagram of the Kronig-Penney model it says:

  ...the energy band slope dE/dk is zero at the k-zone boundaries.

and referring to the gradient:

  This is a feature common to all E-k plots, even those characterizing real materials.

Why is the gradient zero at the k-zone boundaries (i.e. edges of Brillouin zones)? What does it signify?


texts:
simulate this circuit – Schematic created using CircuitLab

The diagram above is part of my constant current circuit which function as frequency compensation circuit. I was given the time constant from square wave test which is \$7.5\mathrm{ms}\$. How do I find the values of \$R\$ and \$C\$ if I want to achieve time constant of \$0.05\mathrm{ms}\$?

the linear differential equation of the circuit would be:
$$
RC\cdot\frac{\mathrm{d}(E_{in}-E_{out})}{\mathrm{d}t} - (E_{in}-E_{out}) = E_{out}\cdot\frac{R}{R_c}
$$
Note: None of the voltage input or output is given.

So far I have tried letting \$E_{in}=0\$ and get the equation by integrating both sides, then do the same thing by letting \$E_{out}=0\$. So I am stuck with two exponential equations. I am lost as to where do I start with, do I just assign a value for \$E_{in}\$?


texts: What is the difference between "Storage Temp", "Ambient Temp" and "Operating Temp" mean?

texts:
To my understanding, ambient temperature is the temperature of the surrounding area while the unit being worked on is powered. While operating temperature is the temperature of the unit itself under heat and power.
I have seen many different explanations online, and most seem to contradict themselves. If the operating temperature of a unit has a maximum of 100°C, then does that mean the chip/components inside the unit can only operate at a max of 100°C? So that should be taken into consideration when adjusting the temperature of the oven. If so, is the only difference between ambient temperature and storage temperature that there is power being delivered to the unit?


texts: Do chips really need multiple values of decoupling capacitor in the same packages?

texts:
A similar question is asked here: "two bypass/decoupling capacitors" rule? But that question was about parallel bypass capacitors without mentioning package size (but the answers mostly assumed paralleling parts with different package sizes), while this one is specifically about parallel bypass capacitors in the same package size.

I recently attended a course on High speed digital design, where the lecturer went to some length to explain that a capacitor's performance for decoupling was limited almost entirely by its inductance, which in turn was almost entirely due to its size and placement.

His explanation seems to clash with the advice given in many datasheets, which suggest multiple values of decoupling capacitor even though they have the same package size.

I believe his recommendation would be: for each package size, choose the highest capacitance that's feasible, and place it as close as possible, with smaller packages closest.

For example, in a schematic from Lattice Semiconductor, they suggest the following:

470pF 0201
10nF 0201
1uf 0306

Q1: Is that 470pF capacitor really helping?

Q2: Wouldn't it make sense to replace all three of them with a single 1uF capacitor in an 0201 package?

Q3: When people say that a higher value capacitor is less useful at higher frequencies, how much of that is due to the capacitance, and how much is due to the increased package size usually associated with larger caps?


texts:
for the 2nd order response of $$1-\dfrac{2\zeta\omega s + \omega^{2}}{s^{2}+2\zeta\omega s + \omega^{2}}$$

I get the plot shown in blue.  How do I go about getting the plots shown in red and green that is basically frequency shifted?


texts: Help identifying this SMD component (IR sensor)

texts:
I have a mini differential IR sensor PCB that serves as the bed probe for my 3d printer.  Looking at the SMD components, there are a few items I can not find or identify.  Does anyone know the part numbers for the components outlined in red in the photo below?

Update:
The black item is definitely a sensor.  The two clear items are certainly emitters.  My question is around part numbers in case anyone recognizes them.  This is a custom part I purchased on aliexpress - not stock for my printer.  The device is fairly simple.  The two emitters produce an IR beam.  The black sensor detects the coincidence of the two beams when they bounce off an object at a fixed distance of about 2 mm.


texts:
This is my first use of the RTCC interrupt for dspic33F and P24h.
I have set the date and the alarm, when the alarm goes on, the LED attached in PIN 15 will blink. The code compiles but there is no result on the LED.

here is the code:

#include<p33Fxxxx.h>

 volatile unsigned int counter=0;

 void __attribute__((interrupt,auto_psv)) _RTCCInterrupt(void)

 {
     counter=1;

 _RTCIF = 0;     // clear flag

 } // RTCC interrupt service routine

 void initRTCC( void)
 {
    // Enables the OSCON write and set
    //_SOSCEN =1;
    asm volatile ("mov #OSCCON,W1");
    asm volatile ("mov.b    #0x46, W2");    // unlock sequence
    asm volatile ("mov.b    #0x57, W3");
    asm volatile ("mov.b    #0x02, W0");    // SOSCEN =1
    asm volatile ("mov.b    W2, [W1]");
    asm volatile ("mov.b    W3, [W1]");
    asm volatile ("mov.b    W0, [W1]");

    //_RTCWREN = 1;       // unlock setting
    asm volatile("disi  #5");
    asm volatile("mov   #0x55, w7");
    asm volatile("mov   w7, _NVMKEY");
    asm volatile("mov   #0xAA, w8");
    asm volatile("mov   w8, _NVMKEY");
        asm volatile("bset  _RCFGCAL, #13");    // RTCWREN =1;
    asm volatile("nop");
    asm volatile("nop");

    _RTCEN = 0; // disable the clock

    // set 07/11/2011 MON 23:59:30
    _RTCPTR = 3;        // start the sequence
    RTCVAL = 0x2011;    // YEAR
    RTCVAL = 0x0711;    // MONTH-1/DAY-1
    RTCVAL = 0x0159;   // WEEKDAY/HOURS
    RTCVAL = 0x5930;    // MINUTES/SECONDS

    // lock and enable
    _RTCEN = 1;         // start the clock
    _RTCWREN = 0;       // lock settings
 } // initRTCC

 void setALARM( void)
 {
    // disable alarm
    _ALRMEN = 0;

    // set the ALARM for a specific day of)
    _ALRMPTR = 2;       // start the sequence
    ALRMVAL = 0x0711;   // MONTH-1/DAY-1
    ALRMVAL = 0x0200;   // WEEKDAY/HOUR
    ALRMVAL = 0x0100;   // MINUTES/SECONDS

    // set the repeat counter
    _ARPT = 0;          // once
    _CHIME = 1;         // indefinitely

    // set the alarm mask
    _AMASK = 0;
    _ALRMEN = 1;        // enable alarm
    _RTCIF = 0;         // clear flag
    _RTCIE = 1;         // enable interrupt

 } // set ALARM

  main( void)
 {
    TRISB=0;
    initRTCC();
   setALARM();
   _RTCIF = 0;

    while( 1){

        if (counter==1) {

            PORTB = 0xffff;
            counter =0;}

    }
    // repeat the main loop

 } // main


texts: How can I improve this Ethernet differential pair?

texts:
This is my first 100 Mbit/s Ethernet project (I am doing it to learn more about differential signals).

I did two things that I don't know if are good or bad in this particular case.

One is to route under the signal transformer. It is only slightly on the border, but I didn't find any other way to route it, without using vias to swap the pair.

What do you think? It would be better to use vias (and an impedance mismatch), or route so close to the inductor?

Also, I tried the differential tools in KiCad, and I matched both pairs to the same length (otherwise, one track is about 6 mm longer). Is this a good practice for Ethernet?

This is a capture of the PCB right now:

This is the schematic that I am using. It uses the lan9512 reference schematic. To be honest, I am no idea of the impedance on my design. I am not sure if I have to use 50 ohm or 100 ohm.

I include the impedance calculation for a double sided PCB, FR4 1.6 mm height and 1.6 oz copper (35 µm)

As you can see, the track with is 0.8 mm!! - way too large.

This is the final version. Track with 1.6 mm, gap 0.16 mm (minimum in my cheap PCB provider).

Thank you everybody for this valuable master class. I will read a lot about differential pairs.


texts: STM32 CAN bus receive interrupt is sometimes not fired, and CAN transmit sometimes times out

texts:
I have two STM32 boards connected via a CAN bus. They periodically transmit a message to each other.

For some transmissions however, HAL_CAN_Transmit returns with a timeout HAL_TIMEOUT. Similarly, sometimes the CAN receive interrupt does not get fired. There is not a real pattern when it works and when not. However, resetting a device seems to induce timeouts more often.

When investigating the signals with a scope, they appear to be fine. The receiving transceiver acknowledges the signal as well even when the CAN receive interrupt is not fired.

What could be the problem in this case?

This is the code to transmit a message. It is called by the main loop.

void send_can_message_handler(void* task)
{
    hcan.pTxMsg->StdId = 0x321;
    hcan.pTxMsg->ExtId = 0x01;
    hcan.pTxMsg->RTR = CAN_RTR_DATA;
    hcan.pTxMsg->IDE = CAN_ID_STD;
    hcan.pTxMsg->DLC = 2;

    hcan.pTxMsg->Data[0] = can_messages_sent;
    hcan.pTxMsg->Data[1] = 0xAD;
    HAL_StatusTypeDef status = HAL_CAN_Transmit(&hcan, 500);
    can_messages_sent = can_messages_sent + 1;

    if (status == HAL_OK) {
        uint8_t data[2] = { 79, 75 };
        HAL_UART_Transmit(&huart1, data, 2, 100);
    }
    else if (status == HAL_ERROR) {
        uint8_t data[2] = { 69, 82 };
        HAL_UART_Transmit(&huart1, data, 2, 100);
    }
    else if (status == HAL_BUSY) {
        uint8_t data[2] = { 66, 85 };
        HAL_UART_Transmit(&huart1, data, 2, 100);
    }
    else if (status == HAL_TIMEOUT) {
        uint8_t data[2] = { 84, 73 };
        HAL_UART_Transmit(&huart1, data, 2, 100);
    }

}

This is the interrupt code.

void USB_LP_CAN1_RX0_IRQHandler(void)
{
    /* USER CODE BEGIN USB_LP_CAN1_RX0_IRQn 0 */

    /* USER CODE END USB_LP_CAN1_RX0_IRQn 0 */
    HAL_CAN_IRQHandler(&hcan);
    /* USER CODE BEGIN USB_LP_CAN1_RX0_IRQn 1 */

    FillBuffer(&canBuffer1.State, hcan);

    // Enable receiving again.
    if (HAL_CAN_Receive_IT(&hcan, CAN_FIFO0) != HAL_OK)
    {
        // Handle error.
    }

    /* USER CODE END USB_LP_CAN1_RX0_IRQn 1 */
}

FillBuffer simply copies the data to a buffer.

void FillBuffer(CanBufferState* state, CAN_HandleTypeDef hcan)
{
    for (size_t i = 0; i < 1; i++)
    {
        state->Buffer[state->WriteIndex] = hcan.pRxMsg->Data[i];
        state->WriteIndex = (state->WriteIndex + 1) != BUFFER_SIZE ? state->WriteIndex + 1 : 0;
    }
}


texts: Controlling motor speed with PID how to scale PWM to RPM and back

texts:
I want to control the speed of a motor using PID controller. My problem is, the valid PWM range I can set in my microcontroller is from 0 to 199 but I measure the speed of the motor (using an encoder) in range of ~50 to 6000 RPM.

How can I meaningfully interchange these values?

Example:

I set the target speed to 6000 when motor is at 0RPM. Then the PID starts and at that moment the error is 6000...so the PID gives maximum output which will be 32767. But I only can set the timer PWM from 0~200.

I am using the code in AVR221 application note and there every variable is signed integer (no floating points). My own micro controller is stm32 that can handle floating points efficiently I beleive.


texts:
I have some signal which I have measured N different times and I want to calculate the noise power spectrum of it. Intuitively to me the way I would do this is simply calculating the power spectrum of the noise. To do this I would take the magnitude square of the fourier transform of the auto covariance of the standard deviation over my N different trials. That is a bit of a mouthful so I'll try to clarify what I mean. First I want to get the noise from my N repeated measurements, so I take the standard deviation over the N measurements and estimate this as my "noise waveform". Then to calculate the power spectrum I do the usual routine which is by taking the fourier transform of the autocovariance, and squaring the result.

This seems intuitive to me, however I can't find any text books or journal articles that confirm my intuition, so I'm left being a bit confused about whether this is really the right technique or not. Could anyone shed any light on the matter if they have experience with this?


texts: What is the simplest way or best topology for an 9v dc battery input to generate four 2.5v dc/250mA each isolated outputs?

texts:
I am looking for something simple, and what does not require difficult to solder surface-mount components.
I came across a complete push-pull solution (minus transformer) using LT3999, only to find out that it would be nearly impossible for me to solder it (msop10-0.5mm with power pad).
I would also prefer a solution without feedback from secondary, using ldo regulator instead.

Any suggestions would be appreciated.


texts:
I am again involved an RF design and I am unsure on how to connect up the Balun, minicircuits application note suggests that it is dependant on the polarity/phase of the input signals (which makes sense) but I have seen conflicting implementations of the Balun in evaluation boards from analog devices.

The app note suggests a configuration like such:

{**+** ---- [P* S] --- **Out**}

{**-** ---- [P S*] --- **Gnd**}

In order to achieve an output which is twice that of the input signal, and this is indeed my aim as I am using a frequency synthesizer with complementary RF outputs.

In the evaluation board I have seen:

{**+** ---- [P   S] --- **Out**}

{**-** ---- [P* S*] --- **Gnd**}

This is also complicated by the fact I am using a config K balun (Tri-Filar) from minicircuits, which also states in the datasheet that the primary port is/should be connected to ground.

So my question is, does the way in which I connect my signals to the Balun matter (either Primary or Primary*)?
and should I be concerned about the config K datasheet telling me to connect the primary to ground?

Many thanks


texts: What is the unit of accelerometer module output

texts: I am on a project to track the human body motion in to a 3d design and animation software. I found that acccelerometers are used for these purposes. According to my project what I will need is the path coordinates on which the human hand or other part moves. This can be done if I get the speed and integrate them i will find the path. But accelerometers by name seems that they gives the acceleration of the object they are attached, that is an object at rest will output zero and at shake time output some value and at motion time then output zero. So my question is this that does accelerometers outputs the accceleration of object or the force applied on them at a direction? If it is the force applied on a direction then it can work for me.


texts:
I have a circuit that should be protected from high voltage. Is there any component other than a fuse that I don't have to change every time? Something like a switch that activates only when high voltage is supplied, diverts the flow and grounds it, and then closes.

Sorry, I can't scan the schematic right now but I can give you information. I have a triac connected to a submersible motor via a MCU IC mounted on PCBA. The problem is sometimes there is a short circuit due to water. I want to know how to protect the circuit in this case as I already have fried it twice. Is an optocoupler or solid state relay advisable for isolation?


texts: Why is a short circuit in the secondary winding of a transformer reflected on the primary side?

texts: I was reading this answer and I would like to understand why if the secondary is short circuited the primary winding will also reflect the short circuit despite the fact that they are isolated. Would the electromagnetic flux through the core be increased with a short circuit on the secondary? If the secondary is shorted I guess it would be as if no turns were present. How would that draw more current from the supply at which the primary is connected?


texts:
Are there any disadvantages in measuring H Bridge current only via 1 shunt resistor?
Since it will be made by hand on a perf board the only disadvantage will be the possible longer wires that connect both drains of the lower N FET half bridges to the shunt resistor.
Mosfet driver will be ir2110/13 but that is a discussion for another post :) . I read application note from infineon and saw that there is a reverse current flow and ground going "below ground".
If I'm correct, current from forward biasing a diode when the bridge fets are HiZ will flow from ground to VCC and it will affect both configurations.
Output from the comparator/ OR gate goes into the classic Threshold reached -> shut off the bridge controller.
Yes, the sense resistors are huge but I don't care about the wasted power, resolution is of greater importance from DAC. And I forgot to put the ballast capacitor from VCC to Ground. Current of the bridge will max out at about 5 Amps.


texts: Oscillations in Master-Slave High Current Source

texts:
I am attempting to trouble shoot a circuit and I am a bit stumped. The circuit is high current source (10-20A) based on a master-slave configuration using OPA549 high power op-amps. There is one master and 4 slaves. A set point voltage controls the current depending on the load resistance. In this case the load is wire wound coil with 1 ohm resistance.

When the set point voltage is positive the circuit works as expected. However, when the set point is negative the circuit exhibits oscillation about the set point. From reading, I realize such configurations suffer from stability issues when driving capacitive loads, but I imagine the load in this case is predominately resistive and inductive in nature.
Maybe a variations in the op-amps lead to them fighting to regulate the output and I should increase the isolation resistance at each output. However, I am puzzled why I only see oscillations for negative voltages.  Both supply voltages also show oscillations when the set point is negative as well.  I suspect the oscillations in the supply voltages are caused from the variable current draw of the op-amps and not the other way around.  The output voltage (labelled N1) and the AC coupled supply voltage are shown below.
Any thoughts would be greatly appreciated. Thanks in advance.


texts: Sending digital sensor ouput over cable upto 30meters

texts:
Description:

This is a DIY home automation project to use a touch panel to control mains lights.

I am using a Capacitive Touch Breakout board for the AT42QT1010 touch sensor IC (see references below).
I need to send it's output over a long cable to an existing relay module. The basic circuit is shown below:

simulate this circuit – Schematic created using CircuitLab

The relay module inputs are described as:

  Principle of operation of low-voltage push-buttons: manual input
  channel is a TTL level (with +5 V and a current of several
  milliamperes), which expects a circuit to a common signal GND. Channel
  input is considered activated in a moment when button is pressed. At
  the same time, channel input is deactivated when button is released.
  So it is required to use pushbuttons without fixation and with
  normally open contacts

The above touch IC is perfect for feeding into the relay module as it has a momentary output.

I've built a breadboard implementation that works as expected but in the real world the relay module itself will be up to a max of 25-30 meters away and the touch panels with the AT42QT1010 will be in a wall in a room.

My question/problem is:

What is the best practice way to reliably transmit the touch IC output signal over cable lengths of up to 30 meters and to ensure no false triggers at the relay end from inductance and other interference from mains cables and storms (and ideally how to protect the touch sensor circuit and the relay module input from said issues)?

References:

Touch IC datasheets
relay module

Edits:

1: I should have noted that this diagram is drawn from memory and just an illustration of the two distinct components and how I currently connect them - the config of the transistor switch was how I currently test the system on the breadboard and is open to be changed to handle the long cable issue.

The mains lamp is shown for illustrative purposes as that is what I expect the relays to switch in the future.

3: The relay module is an 8 channel device - the input shown doesn't directly drive the relay - there is internal circuitry that does that-the spec says the input is TTL 5v level.


texts:
I want to know if there is a simple way to take a common pc psu that takes 120/230vac as input and convert that input to 12 volt DC. Without inverters for use off-grid. This is a desktop gaming PC not a laptop with a ac/dc adapter

Also I am asking about electronics and circuitry contained in the psu not a tip or trick.


texts: THT decopling capacitor spacing from the TQFP uC's power pin

texts:
simple question - how close can the uC's power pin (TQFP pad) and a ceramic cap's PTH pin can get so the PCB fabrication process or later exploitation would not go wrong ?
Some ballpark figures for common equipment available in most fabrication houses are desired. uC is going to draw current from a 3.3V rail.


texts:
I'm trying to rig up my door to be unlockable using RFID and an Arduino. The problem is the actual mechanics of unlocking the door. There's a few limitations:

I can't actually unlock the door. It's permanently locked and can only be opened from the outside with the key.
It's a handle, not a knob
It's an incredibly stiff handle, so any mechanism that would actually turn the handle would need a significant amount of force
I'm renting the place, so I can't make any major or permanent modifications to the door or the door jamb or anything.

I tried using a motor and threaded rod to make a linear actuator, but that's slow and loud. I'm trying to consider whether it would be practical to put a tiny solenoid in the hole where the door's bolt goes when it's closed. (The hole in the strike plate in the door jamb) The hole is much larger than it needs to be (1" deep for a 1/2" bolt), so theoretically, if I had a solenoid that's 1/2" long when unpowered, it would fit in there, and could directly push the bolt so the door could be opened without turning the knob.

Unfortunately, I don't have any experience with this sort of thing, so I have no idea if this is even remotely practical. What would you recommend? Is a tiny solenoid a reasonable solution, or am I better off finding a way to physically turn the door knob?


texts: Is there an IC with a series of 2-input switches that can have all elements switch with one signal?

texts:
I want to select either input A's 4 signals, or input B's 4 signals.
So I'm more interested in using 3-pin like switch, that can short circuit from the either A or B (not open or close one input)

Is there such IC that holds a series of 2-inputs switches, that can change the state of all at once, or should I just stick to a mux or program a CPLD?


texts: What does this symbol mean on my Samsung travel adapter?

texts: The charger was bought in Austria two years ago, and I know about all symbols/labels except this one. Google reverse image search did not help.


texts:
Well I already asked some about this but now my doubts have evolved, hehe.

So, here is the thing.

If using a CV PSU in a parallel connection, V would be same and Amps would split equally between units connected right? if units are all the same.

If so, my doubts are these:

If units to be connected push 50,5V when driven at 1,15A, then, how would this PSU suit for the parallel connection:

Meanwell HLG-240H-48A

This PSU acts as CV as long as it doesn't reach current limit, once current limit is reached, it goes to CC mode. In CC mode, Voltage range is 24 - 48V. Current limit is 5A. Rated power is 240W.

In CV mode on the other hand, Current can be adjusted from 2,5A to 5A and voltage from 44,8V to 51,2V.

Units to be connected have a max current of 4120ma.

My idea is to use PSU in CV mode, adjusting Amps to 4,6A and volts to 50,5V.

So, given this config, if I connect 4 of these LED units to the PSU in parallel, those 4,6A should then be splitted en the 4 units and give 1,15A and the constant 50,5V to each? After having PSU adjusted to 4,6A and 50,5V through potentiometer??

Does this sound viable? Would current be split correctly? Do I need current limiting resistors? if so, how should I use them? What if I don't use them and just connect the 4 LED units in parallel directly to the PSU previously adjusted to 4,6A and 50,5V?

Any help will be much appreciated.

Thanks.


texts:
I am following the YouTube tutorials by Ben Eater to build a 6502 computer (https://www.youtube.com/playlist?list=PLowKtXNTBypFbtuVMUVXNR0z1mu7dp7eH). I got everything to work until the part with the interrupt handling using the W65C22 Versatile Interface Adapter.
For some reason my W65C22 chip keeps triggering interrupts. I measured the output voltage of the IRQB pin and found it is always about 1.5 V. I don't know if it keeps switching between high and low very rapidly and my multimeter just measures this value as an average, or whether it actually stays constant at this level.
I checked the datasheet and found this paragraph below, and I only understand about half of this. But it does talk about some difference between the W65C22N and W65C22S. And I realized I got the W65C22N version while Ben Eater is using the W65C22S in his videos.

The IRQB output signal is logic 0 whenever an internal Interrupt Flag bit is set to logic 1 and the
corresponding Interrupt Enable bit is logic 1. The IRQB output is a full output driver that outputs both logic 1
and logic 0 levels. The W65C22N and older NMOS and CMOS IRQB output is/was an open drain pull
down only, thus allowing the IRQB signal to be wire ORed with an external resistor for a common
microprocessor IRQB input line. The W65C22S IRQB can be wire ORed with a pull down diode that is
forward biased when IRQB is low. See Figure 3.4 IRQB for the IRQB buffer schematics for both the
W65C22N and W65C22S.
The IRQB pin on the W65C22S is a standard totem pole output. The W65C22S IRQB signal was meant for
logically ORing rather than wire ORing the IRQ’s of a system. This change was made to improve the low
power, high speed characteristics of the part. For systems that have wire ORed IRQB outputs a solution is to
place a low voltage diode (<0.5V) in series with the W65C22S totem pole IRQB output.

(Page 31, of this datasheet)
Does this explain the behavior of my chip? What do I need to do, to get it working properly?


texts: Noise cancellation for electromagnetic signals

texts:
I am working in the oil field with tools which I need to connect by cables (which "should be shielded") to computers. Most of the time when I communicate with my tools, I face grounding issues. I tried to ground the computer but it didn't always work, even when am trying to use the laptop to minimize that problem.

Does anybody know how I can reduce or cancel that noise to get better communication with my tools?


texts: Maximum USB 2 length (printer in another room)

texts: I want to run a printer in another room in my house WITHOUT networking.  My needs require a direction USB connection.  Will I have trouble running a USB beyond a certain length of cabling?


texts: What happens if there's no resistor before the ISET pin of a MAX7219 LED driver chip?

texts:
I have a bunch of spst-no buttons each with an led inside. I've just hooked them up to a MAX7219 and they are very dim (when hooked up directly to the microcontroller they're fine).
My guess is the buttons all have resistors inside, but they're all sealed up so there's no way to know without destroying them.
If they all have their own individual resistors, can I get away with removing the single resistor before the max7219 (or reduce it down from 10k to a lot less?)
Edit:
To clarify, If I remove the resistor before the MAX7219, is it likely to break the chip in some way (considering that there are resistors before each LED)?
Here's a quick and dirty simplified schematic. Is it safe to remove R1 if R2 exists? My understanding is that without a resistor, an LED is likely to burn out. If that's what happens without R1, then the MAX7219 will be fine with a lower resistor value and I can probably play around a bit to try and improve the brightness of the LED.
Voltage coming in is I think 5V (from a usb connection)

simulate this circuit – Schematic created using CircuitLab
This is the datasheet for the button: https://www.tme.eu/Document/9b8f20f491475d99dbf596e24530b068/r13_523.pdf - I'm guessing 100M Ohms "Insulation resistance" is the total of the resistor + led?


texts: Do you know any tricks/hacks to perform arithmetic operations with shift registers?

texts:
The trivial case is to use SRL to express multiplication:
val * 2^num => val sll num
val sll 2 + val sll 8 => val * 10

Do you know any other cases like for instance:
val*(2^num) + 1 => ?

How do you use SRLs?


texts: Using the emulator with Android Open Accessory hardware

texts:
I have an Arduino + USB host shield. I would like to start developing with the Android Open Accessory Framework.

Can I connect my Arduino to the Android Emulator whilst developing? Or do I need to buy a compatible handset?

Cheers,

Marcus


texts: How does program execution happen in firmware?

texts: I have heard from people working in firmware domain, that there is no Operating system controlling firmware (eg firmware in a USB drive). There is just a single thread running in a while loop waiting for an external command, and this is the start point for an interrupt to happen, followed by a ISR and the control flowing all the way till the hardware. But fundamentally what is that part of hardware that is executing the firmware code ? Is there a CPU or is it ASIC based code which is triggered as long the device is powered. I fail to understand the paradigm shift from a regular CPU-OS based system to a firmware.


texts: Why SS and MISO of sensor is permanently high?

texts:
I have a brand new acceleration/giro sensor evaluation board which I want to interface with ESP32 via SPI bus. After spending few days trying to make it work, I have discovered that sensors SS(CSB) and MISO pins are permanently HIGH (3.3V). In my code I'm implementing the required power up sequence described in the datasheet on page 23. But Chip Select and MISO of the sensor stay always HIGH, even when it is only connected to DVDD and GND.

I have contacted the technical support. But I wonder maybe there is something I'm not aware of. What could cause such an issue?

Datasheet of Murata SCC2230 sensor

Datasheet of evaluation board


texts: When are positive-sequence and negative-sequence equivalent impedance the same?

texts:
One of the topics we covered in an introduction to power systems class was using zero/positive/negative sequence networks to analyze faults in networks. For many problems, this requires setting up positive and negative sequence networks and their equivalent impedance.

My understanding is that balanced/static (?) components have equal positive/negative sequence impedance, while this can be different for generators (I think we're limiting ourselves to synchronous generators).

On to the real question: in one of the examples we are working out the fault current of a SLG fault, and a table is given with different negative/positive sequence impedance for the generator (as I would expect) but according to the solutions, the equivalent negative sequence impedance is the same as the equivalent positive sequence impedance (even though the generator impedance is used to calculate it).

So, what gives? Is this a special case for SLG faults, an approximation, or perhaps just a mistake?

(pretty much the entire faculty seems to be on vacation, and as a Physics major I don't know that many people that know this stuff... thanks in advance!)


texts: How to choose an off the shelf transformer for DC-AC inverter?

texts:
I am designing a simple Push-Pull converter to turn ~12Vdc into ~12Vac which I then want to put into a transformer to get ~170Vac (turns ratio of 25) and then rectify it back to DC.  The system will be outputting 150W at maximum.

I am incredibly stuck on what to do about the transformer.  I see pre-made configurations with specific input/output voltages, but none are close to what I want, and from what I've read they are fine-tuned to that relationship with saturation, etc.  Are those alright to use?

I've also been reading about designing custom transformers, but it seems like none of them talk about how to actually choose or find the flux density to use.  For example, say I decided to use this core.  I can see the area but I am unable to extract the other relevant information from the datasheet.

Honestly I would prefer an off-the-shelf solution but I will design my own, I just can't seem to find the information I need.


texts:
My ATmega1284 MCU appears to behave strangely in a number of ways. I know, I'm nuts, but here it goes... I'm using a usbtiny AVR pocket programmer with avrdude on Ubuntu Linux 15.10. I am wondering if the MCU is failing.

If I try to use function prototypes with a function definition (the "test2" function), the compiler doesn't complain but appears to program the MCU, and the MCU will randomly seem to apply power at different pins on PORTD (from what I've seen). I'm not being specific because it does appear to be a specific problem.
For some reason when I've tried flashing an LED using the "_delay_ms();" function with "avr/io.h" included, everything will appear to compile fine, but no matter what value I pass in as a parameter, it doesn't seem to make a difference in the flashing speed of the LED whether it's 500 or 5000000. I've also tried change the value of F_CPU several times, but that didn't change anything.
Now, what I am specifically trying to do for kicks, is light up an LED on a 7 segment LED display with a single pin on port D to start, when I have continuity between PORTB1 and ground. But, again the compiler doesn't complain and it just acts strange. It almost doesn't seem to compile the if statement at times, and will just flash the single led very quickly regardless of the continuity on PINB1. I know, my explanation is stupid, and I would hate my explanation too if I were you, but I really don't know what to think.

Here's the code:

    #define F_CPU 6000000UL  // 6 MHz

    #include "avr/io.h"

    void test2(void);

    int main(void) {
        DDRB &= ~(1 << PINB1);
        PORTB |= 1 << PINB1;

        while (1) {
            if(bit_is_clear(PINB, 1)){
                DDRD |= (1 << PIND6);
                PORTD &= ~(1 << PIND6);
            } else {
                DDRD &= ~(1 << PIND6);
                PORTD |= (1 << PIND6);
            }
        }

        return 0;
    }

    void test2(void){
    }

Here's everything I'm doing to compile and program the MCU:

avr-gcc -O -mmcu=atmega1284 -c main.c -o main.o

avr-objcopy -j .text -j .data -O ihex main.o main.hex

sudo avrdude -c usbtiny -p m1284 -U flash:w:main.hex

EDIT:
Ok, I didn't understand how F_CPU worked... Thanks... I tried looking to the datasheet to see what frequency the MCU operates at by default and I couldn't find it, so I'm just going to skip that till I figure that out... Here's an example something else I tried. I just now tried deploying with this code and the led blinks quickly as expected:

    #include <avr/io.h> // AVR IO library

    //void test(void);

    int main(void) {
        DDRD |= (1 << PIND6); // set D6 (LED) to output
        while (1) {
        PORTD ^= (1 << PIND6); // toggle D6 (LED)
        }
        return 0; // never reached
    }

    //void test(void){
    //}

Then I try with the function prototype and definition uncommented as shown below and it stays on steadily:

    #include <avr/io.h> // AVR IO library

    void test(void);

    int main(void) {
        DDRD |= (1 << PIND6); // set D6 (LED) to output
        while (1) {
        PORTD ^= (1 << PIND6); // toggle D6 (LED)
        }
        return 0; // never reached
    }

    void test(void){
    }

I just don't get why there's so much inconsistency there... It makes me think there's either a problem with the MCU or the compiler

update:
Well, I just ditched the AVR and got a TI MSP430FR6989 and it's terrific! Love texas instruments! Good documentation, everything works as expected!


texts: Is it correct to say that a smartphone cable is only a "1A" cable?

texts:
A store owner said that some lower quality smartphone charging cables are only "1A cables", so if you want 2A, those cables won't do the job.

Is it correct to say a cable is only 1A? Does the metal wire inside of a cable get so thin that it can only support 1 Ampere of current to pass through it? How thin does a cable have to get, before it limits the current that can pass through it to be 1A only? I was thinking the cable is bad only because it has higher resistance than usual (but should be still low, like 50 Ohm?). The current decreases, according to V = IR, because V stays the same but total R has increased due to the cable having additional resistance. So the current decreases, but it might still be 1.8A or 1.7A, not necessarily limited to 1A.


texts: Reading digital wafevorms via VXI11 from the LeCroy wavesurfer 510/MS-500

texts:
I automating a test with an osciloscope via VXI11 with python's vxi11 package. I am using the remote control manual given by LeCroy.

I am trying now to extract the raw Waveformdata according to page 254 with the waveform command like this:

import vxi11
instr=vxi11.Instrument(instrIP)
raw_data = instr.ask_raw(str("CHDR SHORT; C9:WF?").encode("utf-8"))

which works for analoge channels, but I want to get the recording of the MS-500 digital channels, which I already recorded.

I tried already C9:WF? (causes fatal error 1597), Digital2:WF? (error log: illegal header path for command) and don't know what else to try, if anybody has an idea :)


texts: Can a dependent voltage/current source have some impedence/admittance,respectively?

texts:
Im studying 2-port networks, for Z parameters equations, there is general equivalent circuit given, in which dependent voltage source is given, I do know about dependent voltage sources, but do these sources have some impedence? i.e Vx = Z*I, where Vx is a dependent source ?

In image, red highlighted circuit;
 "circuit"


texts: Component identification (SMD) - Beelink X55 Ultimate

texts:
Recently my NUC has decided to release some magic smoke. I found two problematic components in it. F1 fuse, which failed (?) to protect the board and U10 which has manifested a nice eruption point.

U10 seems to be marked as B3103 J1306E (or B8103 J1306E) but I cannot find a replacement component. Contacting the manufacturer has so far not yielded any results. Anyone have any ideas what it could be?

Any help on identifying the fuse would be appreciated, though I assume the problem is with U10 which malfunctioned and not the fuse?

Late edit:

Well, I finally fixed the issue. As was correctly stated by @ChrisStratton in a comment this was not the original failure. The short from 12V to ground persisted, but the replaced mosfet did not blow as I connected the device to a current limited PSU, limited to 12V@0.15A, it did get toasty warm. I finally tracked it down to a faulty ceramic capacitor (or perhaps it was promoted to a 0R bridge resistor!).

Removing that sucker fixed everything up and now it is booting back up! Seems it purpose was just a capacitor bank, but still need to replace it, for now the device runs without it. As for the value, no idea, I'll probably just add a beefy cap (1uF).

The bloody fuse still works, YOU HAD ONE JOB TO DO FUSE!

Was fun to learn to do to SMD rework, always wanted to do it but never found an excuse :) Luckily the board and components were small enough not to require PCB heater...

For posteriorities sake, in hopes it helps someone else, the faulty capacitor was found between Q168 and Q171 as shown in the bellow image (capacitor is already removed).


texts: Can double-pole breakers trip each side separately?

texts:
How many of you have used double pole breakers?
Are double-pole breakers just two single pole breakers physically joined?
Someone  stated that only one side of the double pole breaker provided short circuit protection.
Picture below is the exact GE model. Anyone familiar with it? Does only one side trip?

The person who tested the 2-pole breaker to have only 1 side tripping is an US citizen who has done many tests with it. See the middle of this blog.  http://myphilippinelife.com/philippine-electrical-wiring/comment-page-1/
Could it be a counterfeit product?
Quoting him:

"The assumption that the two halves of DP breakers can serve as SP breakers proved to be very wrong.  The double-pole breakers are NOT just two single pole breakers physically joined.  We found this out the hard way when we had a total short in one of our circuits and the 20 amp breaker did not trip, but instead melted a #12 AWG wire.  This must have been a huge overload, far beyond 20 amps.
We then tested the breakers on a test circuit.  We found that only one side of our double pole breaker provide short circuit protection. It’s unknown which side may provide over current protection.  Presumably, breakers made to be used as single-pole provide both protections in a single breaker, as do double-pole breakers used as a unit."

I need to know this because I'm powering up 240v load and there is ground wire to the enclosure. If not both can trip, what would happen if the live line that shorts to the enclosure is connected to the breaker side that doesn't have short circuit protection?


texts: Grounding house battery to vehicle chassis

texts: For a solar power installation in a van/RV, should the negative terminal of the house battery —the battery that is charged by the solar panel and used to power devices and appliances whether or not the vehicle engine is running— be grounded to the vehicle chassis?  If there are multiple batteries (connected in parallel for a 12V system), should each battery be grounded to the vehicle chassis, or should only one (or none) of the batteries be grounded to the vehicle chassis?  System capacity is fairly high, with inverters capable of putting out up to 300A @12VDC.  There will be a connection to the house batteries from the vehicle alternator/batteries to allow them to be charged from that power source.


texts: Generation of a shorter pulse based on trigger (similar to 555 as monostable)

texts:
I need to create a shorter pulse based on a trigger signal. Trigger signal has a duration between 1 to 10 ms and the desired output should be 0.5 ms.

To do the opposite (longer output pulse than input trigger) one can use a 555 as monostable (shown on the left) but what I need is the situation shown on the right. Is it possible to this with a 555 or with other monolitic IC?

Many thanks in advance!


texts: Clock domain cross and metastablilty problem

texts:
I understand the problem of metastability and understand that we can't get a stable value in a bounded time so we need unbonded time but it is not practical,

so we put another flip flop with no logic to let a complete clock period be available to the metastable state to be stable state

But the metastable state is equally probable to be '0' or '1' as the mechanical analogy of a hill

so why after the ff synchronizer the stable value dout will be exactly equal to the input din ??


texts: How do I choose a value for an X-capacitor?

texts:
I am working on designing an EMI input filter, and I was wondering how I should go about choosing a value (capacitance) for the X-capacitor. I found a post (linked below) which talked about calculating the power factor, and then choosing a cap that gave you a decent power factor (without being too greedy.)
Is this the only way to do it, or are there any other design guidelines I should be aware of?
I know that eventually we would test our board to make sure it is in compliance, but I am more so wondering about guidelines for the initial component selection.
X capacitor selection for SMPS power supply


texts: MOSFET is not turning off when the gate terminal is grounded

texts:
This figure shows a small portion of my circuit:

The maximum Vgs of the MOSFET is 20V. The MOSFET is initially turned on and now I want to turn it off. For that I am grounding the terminal A to ground through a resistor of 1k. But it is not turning off. If I do this without the 1k resistor it is turning off. What could be the possible reason?


texts:
So I recently bought a motorised pedicure set thinking it would be some amazing thing. However, I used it once and the batteries (4 AA) died after about half an hour and not before getting ridiculously hot.

I decided I would take it apart to see what mad electronics have gone into it, and it turns out it is literally just a button and then wired straight into the motor. So I have decided I would like to replace the motor with one that has a higher torque (was really not very powerful so didn't have much effect) as well as possibly a higher RPM.

After taking it apart and finding the motor, I tried to find out what type of motor it currently is but it has no markings or part numbers on it at all so I couldn't find out. I wanted to know this so I could know the characteristics of it and things like that so I know how to get a better motor that would provide a better product!

Here are some pictures of the motor in various stages of assembly and I was wondering if anyone could help out with regards to what type of motor it is, and if anyone has any comments/solutions to some of the issues I mentioned they would also be greatly welcomed!

As it might not be clear from the pictures, inside the 'drum' of the motor are two magnets that the coiled wire sits in.

I have taken the voltage and current readings of it and it is as follows:
Voltage: Anywhere between 4V - 12V it seems to work, towards 12V it starts going a little bit mental.
Current: Around 500 - 600mA.


texts: USB-TTL problem connected to my UART-WIFI module help!

texts:
A question is one to regulate that there warms up very much the chip of my usb-ttl that this feeding to my module uart-wifi as sample in the figure. That can be the problem helps.

PL-2303HX

Tlg10ua03 Uart-wifi

This way connect both modules:


texts:
I'm trying to run standard Blink LED example on Atmega8A, but my LED doesn't blink.
Here is my circuit:

And here is my code:

#ifndef F_CPU
    #define 16000000UL
#endif // F_CPU

#include <avr/io.h>
#include <util/delay.h>

#define set_bit(target, num)    (   target |=   _BV(num))
#define clear_bit(target, num)  (   target &=   ~ _BV(num))
#define toggle_bit(target, num) (   target ^=   _BV(num))

#define DELAY_IN_MS 1000 /* 1 sec */

int main()
{
    set_bit(DDRD, PD7);
    set_bit(PORTD, PD7);
    while(1)
    {
        toggle_bit(PORTD, PD7);
        _delay_ms(DELAY_IN_MS);
    }

    return 0;
}

What's wrong?


texts: How can I correctly wire my switch into my USB-to-Serial adapter cable?

texts:
Referring to this question:
How can I convert a 2 prong connector to USB?

I have decided to go with this solution:
(2) You could use a cheap (from $5) serial to USB adaptor and wire the switch to eg the CTS line. This can be detected by a PC program.
(answered by Russell McMahon)

My questions are what type of wiring should i use? (links anyone?)
I've decided to go with this adaptor:

http://www.amazon.com/gp/product/B00404P0L6/ref=oh_details_o00_s00_i00

How would I connect the actual wires to the serial cable? from this video:
http://www.youtube.com/watch?v=2MlJCMdD8MU (45 seconds)

It appears I need to wire pins 1 and 4. But I can't seem to find the shown serial adapter that would let me solder the wires into a serial port.
Does anyone know where I might get such an adaptor? Or could I just connect the wires directly into the serial port pins?

Thank you all for your expertise and willingness to share.


texts: Driving Smart LEDs (integrated IC) at 24V

texts:
I need the help of someone more competent at deciphering datasheets of obscure components. I am currently building an LED indoor light installation and would like to have hundreds (400-800) of individually addressable LEDs. The most straight forward solution would be to use the common WS2812 RGB LEDs, that however would entail using copper wires as thick as garden hoses to distribute the 5V power. I know there are also 12V LEDs out there, but 24V would be much better. After several weekend nights of research I have finally found a smart LED that might be up to the task and is pretty affordable at the same time, while not drawing incredible amounts of power doing nothing:
IN-PI55TBTPRPGPB from Inolux (Datasheet)
Now the datasheet is fairly readable to me, but I am missing some critical information here. On page 4 there is a property that is named as "R/G/B port pressure - VDS,MAX" and it states 24V. Does that mean I might be able to attach VCC to a 24V rail? The ratings for VCC are not mentioned anywhere.
Every piece of advice is appreciated!


texts: Increasing SNR through sampling and coherent integration

texts:
Let's say I have simple BPSK scheme and a receiver RF stage such that I have an ideal analogue bandpass filter with bandwidth \$ f_{bw} \$ and then a down converter and finally a sampler. I am trying to use oversampling so that I can integrate the inputs through a correlator and increase the overall SNR of the received bits.

I know for sure if the input to the correlator has AWGN noise this will work. However, my friend claims the output of the sampler will have correlated noise and oversampling will not work, due to ideal analogue filter which will essentially make the AWGN noise coloured at the analogue domain. He tries to prove this through the Fourier transform of the noise power at the output of the analogue filter.

I simply cannot grasp this idea, sure the noise at the output of the analogue filter will be also bandlimited but we aren't sampling the Fourier transform of the noise, we are sampling the time domain version of it, once I sample it, the noise power should be distributed all over the frequency axis once it is sampled with oversampling. My noise power should stay the same but the noise should be redistributed to the whole frequency axis of concern after sampling.

His other claim is that my type of thinking breaks Shannon's capacity theorem since I can just oversample infinitely and integrate them to achieve infinite SNR (at least for BPSK). But shouldn't increase in the sampling rate basically means using more bandwidth hence it is consistent with Shannon's channel capacity even though transmitter sampling rate was low but receiver oversamples and then integrates the samples.

I am confident with my thought process but I am not able to find a proper source to prove or disprove them.


texts:
Lets say i have a mosfet where the drain->source voltage is 100 but the gate->source voltage is 5. Do i need a transistor rated for 100v or 5v since at that gate voltage only 5v would pass through?

Also what happens to the other 95 volts in this scenario? Will they contribute to heating the transistor?

Also why does this red box keep whining about quality standards? It would help if it said anything other than "no".

EDIT: schematic


texts: Display power consumption ratio of smartphones and smart watches

texts: What is the most power-consuming part of your smartphone or smartwatch display?  Or is it cpu?  Naturally I think that it will change depending on the situation, but general use is assumed.


texts: Risk of driving solenoid with a higher voltage pwm signal

texts: We have a solenoid which is rated to be controlled by PWM signal "Maximum 325 mA at 7.5 Vdc". The problem we have our controller sends in 12 V output voltage. There is a thought that we could still drive it using the the 12V PWM output. Is there any risk especially with power rating. At 325mA at 7.5 Vdc, the power rating could be 2.4 W. At 12 V if we restrict the max current to be 201 mA (0.201*12 = 2.4 W, can we still work with the same voltage. Is there any risk to the solenoid in doing so?


texts: Power Arduino Nano and 12V pump with DC/DC converter

texts:
First of all, I am very new into electronics.
I need to power an Arduino Nano and a 12V water pump:

I have a Voltcraft sps15-36w power supply that can convert 220AC into 12V DC:

I also have a RY 1205S DC/DC converter, that I want to use to convert the 12V into 5V to power the Arduino, the different sensors, and the relay:

I have couple of questions:

Is there any risk or extra isolation needed to connect the water pump and the electronics to the same 12V power supply?
The 12V->5V converter has internal linear regulation. Is that needed? Can I replace it with another converter without that feature? (I also have a GAPTEC 3S7A 1205S1 )
The 12V->5V converter does not have "short circuit protection". Do I need to add that? Any hints on where can I start looking into that?

Since I am very beginner and I do every possible mistake anybody can do, any extra protection is probably very useful. :)
[EDIT]
I am using a generic relay board without brand like this one.
I was thinking in connecting it directly to the 5V+GND of the arduino, and the SIG pin to one of the digital pins.
It seems to have a 1k resistor, a J3Y transistor, a M7 diode and a relay Songle SRD-05VDC-SL-C, that if I understood correctly it requires 71.4 mA to work


texts: MCU - Two power input: from PoE and DC 12V Switch between them

texts:
I'm using this MCU board that is PoE-powered and it gets out 12V from pin 20. I'm also using an LM2596 in order to get those 12V and then power out 5V to power all board peripherals.
Also, I'm using the same LM2596 to manage the DC input (8-36V).
The issue is that I need that the MCU board will output 12V or will get the 12V from the DC side, because I need also the 3.3V that comes from MCU board.
At this time, I need a sort of switch mechanism that implements this logic:

When DC Input is on, board will be powered from DC input (12V through
pin 20 and the MCU 3.3 step-down converter will power up the 3.3V
branches)
When PoE is on, board will be powered from PoE and the 12V gets through pin 20
When both PoE and DC input are there, it will be powered from the DC input.


texts: How can you split HDMI 1.4b control signals to two displays?

texts:
I have been tasked to implement an HDMI splitter on a PCB along with other interface connections. The intent would be to utilize one built in display and have the option of a second plug-in display with the same visual. I have identified PI3HDX412BDZBEX as a possible solution, but it only manages the TMDS signals, not the control lines for CEC, HPD and DDC.
I think HPD and CEC can be merged easily, but how can or should DDC be split to two displays?


texts: SN7404 inverter strange input low current

texts:
When I connect the SN7404 pin 1 to ground and measure the current, the current is nearly zero (5uA at most). I would expect the input low current (I_{IL}) is usually around 1mA magnitude. I tested to drive an LED using pin 2, the LED is on, but input pin still almost zero current. I tried different SN7404 chip, same results.

I tested 7400, 74LS245, etc the current is around 1mA magnitude when I ground the inputs pins.

any thoughts why the 7404 input low current is nearly zero? thanks!

Here is the chip:
http://www.jameco.com/z/7404-Major-Brands-IC-7404-Hex-Inverter-DIP-14_49040.html


texts: Will SN74HC245N transceiver support TTL RX when blocked?

texts:
I'm actually designing a system with:

~10 "Master" boards that transmit data from slaves boards to a RS485 network
4 "Slave" boards per master one, connected trough a 3 pin jack (5V, GND and half-duplex TTL)

Most of the time the slaves are sending data to the master (and so to the RS485 network), but each time a new slave is connected I need to send it its position (on which master board it is connected). So here's the schematic I want to use:

simulate this circuit – Schematic created using CircuitLab

SN74HC245N functional diagram: (from datasheet)

So each time the micro-controller on the master board is detecting a new slave, it toggles the DIR pin and send the position to slaves (the data sent by others slaves will be lost in this time but that's not a problem).

My questions are:

Will it work?
If, while the master is sending position to the slaves and some slaves are sending data at the same time, is there a risk to damage the SN74HC245N? As it's supposed to be a bus transceiver I think it is protected against this but I'm not sure...

Thank you,
Emerick


texts: Characteristic impedance of RF PCB when narrowing the trace width to fit pad

texts: I am working on a PCB design that should be matched at a characteristic impedance of 50 Ohms. The circuit down converts a 2.4 GHz signal to a signal in the 2 Mhz- 100 Mhz range using a VCO and a mixer. For the board I will be using, I calculated the required trace width to be 1.04 mm but the pad width of the VCO and mixer is 0.30 mm and 0.45 mm respectively. I have used the trace width of 1.04 mm and only narrowed it down to the respective width when connecting to the VCO and mixer. I wanted to know if this will affect the characteristic impedance of my trace and thereby degrade my signal or since the narrowing of the trace only happens at the end of the trace when connecting to the pad, the characteristic impedance will not affected that much by the narrowing?


texts: Vacuum cleaner charging works only with the original adapter - why?

texts:
I have this old robotic vacuum cleaner that I got cheap and was using for a while: https://www.youtube.com/watch?v=nvj8BmijDn4 (not my video)

Now however the charging adapter broke and I've been trying to replace it which seems like a straightforward task, but apparently I'm not educated enough to make it work. First off, some facts:

The old adapter is a simple AC-DC adapter designated JDA-22, outputting DC 22V 450 mA.
The battery of the vacuum cleaner is a 14.4V 3500mAh Ni-MH battery pack (something like this)
Between the adapter and the battery is the charging dock with some basic electronics and a relay that probably does some regulation and magic for charging.

My theory was that I could just order a replacement adapter so I got myself a new 22V 1A DC adapter that fits nicely. Whenever I plug it into the charging dock, the LEDs turn on and everything seems fine, but when I connect the vacuum cleaner to the dock, it charges for less than a second and then I can hear the relay click inside the charging dock and it turns off for a moment (LEDs go off, charging stops). It then comes back up again and continues in this click off, turn on, click off, turn on loop until I disconnect the vacuum cleaner from the dock. Seems weird enough.

So I measured the voltage from the old charging adapter (it's more physically broken than electronically so it's still barely usable) and it's outputting 24.x volts instead of the specified 22. I have a look inside the charging dock and the relay has a designation RWH-SH-124D. The specification tells me that the "Rated coil voltage" and the "DC contacts rating" (whatever they are... not sure. Specified working voltage I think?) are both 24 volts and the new charger is giving them 22 volts instead of 24, so maybe that's not enough to power the relay. I don't have any idea if the broken old charger is the original or someone just retrofitted it because it worked.

Alright, let's get a new 24V adapter. Done (24V 1A DC). Plug it in and get exactly the same behavior as with the 22V adapter. At this point I'm at my wits' end and come here asking for guidance on how to proceed.

What I think may be happening (and have no idea how to fix):

The battery is drawing as much current as possible and the old adapter was only giving it 450 mA which was safe, but now that the new adapters can provide 1A, there's a safety feature in the charging dock to turn off charging if too much current is withdrawn.
The charging dock itself is confused by too much current and just fails under these conditions.
There's some kind of a third parameter in this process besides voltage and current that I'm not aware of or can't think of that is different between the old and new adapters.

Will you help me make this old boy clean some more? :)

EDIT:

So what's wrong with the old one? First of all, the contacts have come loose so they can be pressed into the housing of the adapter so you can't really plug it in any more (EU type). Secondly there's a weird patch on the side of the plastic housing that looks a bit like it has melted at some point and it used to get rather hot while charging so I don't feel overly comfortable using it even though it technically works. The old adapter is similar to this I think, but not exactly, because mine is an EU type plug and mine is rated at 450 mA not 500. Here are some pics of the old adapter to give an idea of what's wrong:

I can't open it up at the moment because it screws together with some special screws and I don't have that driver at hand.

EDIT 2:

Here's a picture of all the adapters with the left one being the old adapter.


texts: Using VHDL integer_vector for a block ram type, how to restrict the integer range?

texts:
Trying to simply infer block rams in a design with varying depths and widths.  I'd like to have one ram definition since it is going to use a vendor specific attribute and it seems like a good idea to keep it confined to one module.
Using integer_vector for the array type it is simple enough to set the range of the array index.  Setting the range of the integers in the array is not so clear.  Is it possible to set the integer range in the signal declaration rather than a type declaration?
I need both the depth and width of the memory to be set by generics where it is instantiated.  Will I need to use a vector type instead of the integer type to be able to do this?


texts: What voltage rating should capacitor be in this LED driver circuit?

texts: I have a circuit that is used to rapidly turn an LED on and off. There is a capacitor in the circuit to provide some buffering (C1). What minimum voltage rating is required when selecting C1? I want C1 to be a through hole component with the smallest diameter/height possible.


texts: Help with reading a blurry circuit diagram

texts:
I read the paper "Digital sound processing using Arduino and MATLAB" and there is a circuit there, you can see it in this photo:

Can anyone please help me read it properly?

Is the 2 resistors connect to DAC or only the upper one?

What is the capacitor size in the audio in? (is it 10uf? 10 pf?)


texts: Conceptual Question About Hemholtz-Thévenin Theorem

texts:
I've been taught that for the Hemholtz-Thévenin's method I need to add an independent voltage source with a current flowing and at the same time "turn off" independent sources of voltage and current to calculate the equivalent resistance.

Then I should just calculate the open circuit voltage on the terminals with the independent sources as they were on the first place.

First, I find difficult to understand this concept, and my second question is: If I have a resistor in series with the independent current source I "turned off" on the first step, does it mean the current in that resistor is also 0 or is it another current as if it was a cable?

I'm basing my question on the following excercise and it's solution:
Find equivalent resistance (\$R_{eq}\$) seen from point A: (Don't mind the spanish).

Solution:

Thanks!


texts: How do i find Current Consumed by Circuit designed on Surface mount PCB without damaging PCB?

texts:
I have a circuit designed on PCB, and components (resistors, capacitors, diodes, Microcontrollers etc.) are all surface mount. I want to find the total current consumed by this circuit. I have traced the schematic of the circuit completely, and the circuit and MCU operate on 3.3 Vdc.
The supply 3.3Vdc is generated through AC 240rms, then half wave rectifier, then filter capacitor and finally 3.3V regulators.

There is also a port left open for the battery but no battery is attached. I want to make circuit portable so that it can work without direct supply that is why I need current consumption of circuit to estimate the battery specifications.

I can't break any connections to measure the current using DMM, because its layered PCB and I am afraid I might damage it.

Is there any other way to find the total load that circuit has or current it consumes??

Note: MCU has the normal operating current of 2.4-5.4 mA.


texts: How to connect 50 A 12AWG cable to a shunt resistor in PCB?

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I'm designing a PCB in which the current of a BLDC motor is measured through a PSG4NTEBL500F shunt resistor. The DC supply of the motor is connected to the PCB through a 12AWG cable and the circuit should handle current up to 50 A.

How can I connect the 12AWG cable to the PCB? I've thought of soldering it directly to a hole, is this approach appropriate for such high current?

How should I connect the wire to the resistor? My copper weight must be 1 oz, so a simple trace would have to have an insanely high width. The resistor will be the only component on the bottom of the PCB.


texts: Help with choosing transformer wire type and sizes for high frequency transformer

texts:
I have been using the following reference to design a HF transformer https://www.ti.com/lit/ml/slup126/slup126.pdf, which I have found very helpful and useful for the core loss section. However when it gets to the winding losses, page 4-10 onwards, the author assumes that the reader has knowledge of their winding structure, winding methods and the like. Unfortunately I do not. I know that Litz wire is used for high frequency, and that one can choose solid wire and foils etc, but I have no understanding how to continue from this point onwards.

He mentions winding breadth of 1.3cm, allowing maximum insulated wire diameter of 0.87mm, and that AWG21 - 0.72mm copper will be used. I am lost at this point. Where do I even begin to find out what thickness of copper and what type of wires I will need to use? How much insulation will my wires need? My application is high voltage also, with max output voltage being 6kV. So I know I at least will need to know how to calculate the insulation thickness that I need - but I cannot find any useful documents that walk me through the process of choosing the wiring structure for the transformer.

Can anyone help with this, or alternatively supply me with a thorough but uncomplicated reference which can do so? I am at a loss as there seems to be so many different options and I do not have the slightest clue where to start.


texts: Designing a network to fit specific amplitude and phase response curves

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If we are given a frequency response curve made up of the amplitude (magnitude) and phase (angle) responses, is it possible to design an electronic network with a transfer function identical to the given ones?

I have been thinking about this. An idea which occurred to me was that if we could design a network with constant amplitude and a specific phase response, and also another with a specific amplitude response and zero phase response, the problem would be solved. However, I still haven't found a way around the sub-problems.

Is it possible to design such a network? It could be passive or active.


texts:
I found in this teardown analysis of the Nissan Leaf drive motor that it runs up to about 10,000 RPM but is an 8-pole motor. My understanding is that the inverter cost goes up with frequency. The Leaf motor at max speed conditions requires the drive to go up to 600Hz, whereas a 2-pole motor at 10,000 RPM should only need a drive frequency of 167Hz.

Why would the design engineers use an 8-pole motor in this case?


texts:
I've been working lately on a new project.
The project is to power a simple LED with a transferred power.

The first thing that came to my mind is "Transformers".
So, I surfed the internet, I found lots of circuits that actually help in making a wirless power device.

This is the schematic:

Source 1.
Source 2.

Parts:

1- Arduino

2- Two 0.02 uf capacitors

3- 2n3904 NPN transistor

The voltage was really small as I used the arduino to generate a 147.7 kHz square wave AC signal.

I tried changing frequency, cpacitors with the same coild.
I had different results.
By different results I mean different deficiency of power transfer.

My questions:

1- Is there a direct relation between them? Is there a clear mathematical equation between them?

My attempt to answer the question: Based of an internet search, I need to calculate the inductance of the wires  the values of the capacitors are set based on the inductor in order to calculate the capacitor required for the frequency that you plan to use.

2- How is the LED turned on? it should be switching between forward and reverse bias so (On-OFF) because I have an AC signal output.

My attempt to answer the question: It is actually tuning on and off really quickly that I see it to be turned on all the time.

3- Are there any parameters I have to keep an eye on that will help in increasing the efficiency?

I looked for gap materials, but let's say that is fixed (air).


texts: What component is this (not a capacitor but looks like it)?

texts:
This component I think I got it from a CRT television (but also might come from a VGA card, sorry for not remembering).

It looks like a capacitor, but it does not have any Fahrad mentioning.


texts: So I want to modify this board in order to add a 40 pins tft connector to drive a 5" LCD 800x480 display so the user can "flip" between HDMI and TFT. I have no idea where to start, could you give me a clue?


texts: arduino due build-in interrupt debouncing

texts: According to the SAM3X handbook it can do debouncing of interrupts "automatically", how would I enable that on an arduino due? The doc http://www.atmel.com/Images/doc11057.pdf states something about setting it directly in the PIO.