texts: Discrepancy between measured and calculated value for capacitive divider

texts:
The circuit above was given and I am supposed to measure the voltage across the last capacitor. Without C1 initially, knowing that this is a capacitive divider, I am expecting 1/10 of 5V, i.e. 0.5V to be measured.
To my surprise, the measured value is 0.0521V.
The digital multimeter used is a Fluke 179 and I suspect that the discrepancy might have something to do with it but I was not able to find any reasonable explanation.
Can anyone explain what happened here?
Measuring the voltage across the first capacitor gives 450.2 mV, which is somewhat close to 0.5V but I couldn't explain why there's a 0.05V discrepancy.
Also interesting is that I observed the voltage across the 1M resistor is 4.58V, which was not expected. Are there any explanations for the two phenomena here?
Edit
Say a capacitor C1 is added across the circuit, will it help to solve the issue of the measured capacitor discharge to the DMM and allow me to measure 0.5V?


texts: How is the shaft of a motor fixed in its position?

texts:
Consider for example a brushed DC motor.
1- Is the shaft of the motor (which is rotor in this case), actually floating mid-air because of magnetic field of stator? Why doesn't it fall down due to gravity?
And what about other types of motors?
I mean, How can we fix a rotating bar inside a cylinder without somehow mechanically coupling them?

2- For outrunner BLDC motors, shaft is mechanically attached to the surrounding magnets around stator. How is stator and all its windings fixed in its position and not falling down?


texts:
Why I should us a transistor to drive an IR LED?

I see many schematics which use the following circuitry:

If I connect the IR LED directly to an Arduino digital pin, it works. But with the transistor circuit, it works better.

Why is that?

(my value of R2 is just for show)


texts: Connecting/disconnecting AC signal via uC

texts:
I want to mix up to four AC signals, that may or may not be DC biased, but will always be between -5.6 and +5.6.  For that I was going to use a summing amp. (If anyone wants to talk me out of that in a comment, feel free, but that's not the main focus of the question.)

I also want to be able to connect/disconnect the signals to the mixer via a microcontroller.  I'm not THAT concerned with a little distortion or delay, since the signals are monotone and mostly for testing purposes.  I have read that a relay is probably my best bet, but I don't have any around at the moment.  Therefore, I tried to design one using the discrete components I have, which are BJTs, MOSFETs, and the normal passives. I read this post, but I'm not really sure how to apply SCRs or TRIACs. The TRIAC's wiki page lost me when it started talking about quadrants, haha.  I just want to pass the signal, or block it.

For instance, I drew up and simulated the following BJT schematic.  Since it's my own creation, I of course don't trust it, but it seems to work, with only 10nA pulled from the control pin.  Could anyone give me a reason why a relay is preferable?

Output is OFF when VCONT=5. Current leakage also shown.

Output is ON when Vcon=0

In reference to Russell's comment, I tried to simulate this circuit:

But the control (shown here as voltage source) cannot be grounded.  In this pic it works, because the control is isolated.  I tried adding a resistor between ground and sources, but that does not allow for full cutoff.

At Russell's behest, I built the NMOS version and it worked even though the simulations show only a dampening for the positive swing:

This was the circuit that was simulated and built/tested:

Simulation result:

Oscilloscope measurement (when forgetting to ground the Source, or having very high R to ground):

Oscilloscope measurement with the 6.8k resistor from S to GND:

Voltmeter measurements:

When Vcon=HIGH: 0 uA from Vcon, 12 uA from signal into input, 9 uA from Source to GND.

When Vcon=LOW:0 uA from Vcon, 0 uA from signal to input, 0 uA from Source to GND.


texts: Thyristor leaking AC? Reading thyristor code?

texts:
I'm refurbishing an automotive battery charger. It uses a full-wave rectifier in combination with a thyristor (which I think is acting as output cutoff). The charger output has is the correct DC voltage, but it has an unusually high AC reading (>3V AC in 12V charge mode, >4V AC in 12V charge mode). The rectifier section has ~1V AC output (typical in the other chargers I've tested), so the AC is coming from the thyristor. Is this abnormal behavior?

How do I properly interpret this thyristor code:

BTW69200NS
7SAFW VU
PHL 7S 232
I'm able to decode the first line, aside from the "S." What's conveyed in the second and third lines?


texts: LTSpice: How to convert netlist to .asc?

texts:
I have LTSpice on macOS.
Is it possible to automatically convert a .cir netlist to .asc file?
In other words, I would like to obtain the schematic file from the netlist. How could I do it?
(I know that I can do the opposite, so from .asc to .cir)


texts:
I'm trying to create a air pump system with a rechargeable battery pack. My question is:

Because my air pump is a positive desplacement pump, which task is to create a vacuum in a container, will its voltage increase above 12V when the workload increase (because vacuum) and will I need a overvoltage protection system for the DC motor?
If so, is it possible to get a overvoltage system that will cut off the current to the momentary ON/OFF switch?

I would also appreciate any comments on the schematics below.

Thanks for any help!


texts:
I know what are logic gates and how to deal with them, and how they are so important in computer architecture. I learnt logic gates combinations and how they work.

Now I would like to know how are those gates designed?

What are the electronic components used to make a logic gate?

I just know some electricity basics!


texts: Driving 3ft (long) ribbon cable from an IC

texts:
I've run into a problem with one of the designs recently.

I need to drive several GPIO pins over a long-ish ribbon cable. I have used a buffer chip between my micro and the ribbon (SN74Abt162244) which is also a level shifter from 3.3V to 5V. Everything worked well until I connected the ribbon. One by one the outputs of the buffer chip started to give up.

The buffer should be able to give 12 mA so I am wondering if maybe ribbon capacitance was a bit too much and overloaded the outputs.

Maybe there is an IC capable of driving such a long ribbon?

Any suggestions are very welcome.


texts: Using the VO2223A to switch a 230Vac LED lamp

texts:
I'm looking for something that can switch on and off a 230 Vac, 26mA LED lamp, under microcontroller control.  Would a VO2223A, driven by (say) a PIC or Arduino, work as a low-current SSR? The load isn't inductive, so I'd hope not to have to use any form of snubber (but perhaps for safety's sake...)  The power consumption of the lamp is just under 8W.

Since I'm looking to run 70 or so lamps (and assuming that such an opto-coupler can be used as a cheap SSR), are there multi-channel variants of the chip?


texts:
Spartan 6 clocking resources. The link here refers to the clocking resources of spartan-6 FPGA. I am using the DCM-CLKGEN primitive described in the link, to generate a 8x clock based on an input clock. It works fine as long as the input clock is stable.

But now i sweep the input clock at every 90 us by ±5%. I see that although the DCM does not lose lock, it takes very long (15 to 20 us) to change the output freq after changing the input frequency. This is for me undesirable. Any suggestions?

This question was posted on the xilinx forum and the suggestion was to reset the DCM everytime it loses lock. But the problem is that the DCM is not losing lock

Also, this was earlier posted on stackoverflow and now has been reposted here.


texts: I am looking for a cheap way to get +24V DC max 3A from computer power supply. I prefer easy soldering solution like DIP, and standard components that do not need to be purchased over internet. Any ideas, please?


texts: Current relationships across a voltage step down convertor

texts:
This question arose from a conversation over the weekend and we tied ourselves in knots trying to get to the bottom of it. I didn’t have time to put a simple circuit together so it would be great to get some expert thoughts on this.

Given a circuit as follows:

With a 12v supply attached we get the following readings:
V1 - 12v
A1 - 50mA
V2 - 5v

(1) With SW1 open, assuming the buck convertor is 80% efficient, what is the expected value of A2?

(2) With SW1 closed, same question/assumptions.

(3) Why?

(4) What is the correct way to talk about the difference between measurements at A1 and A2. Is it correct to say that the excess current (46mA) flows into the negative terminals of the buck converter?

Thanks in advance!

Edits/Clarifications

This is a simplified version of a real circuit that promoted some discussion. The original components were as follows:

Buck converter module: https://www.amazon.co.uk/gp/product/B01MQGMOKI

The module shorts the In- and Out- terminals internally (making SW1 irrelevant as folks have pointed out).

Mini Ammeter (A1): https://www.amazon.co.uk/gp/product/B00PGOUX0W

This module forced me to place the ammeter on the return side of the circuit since it effectively shorts the -ve power and test terminals.


texts:
While going through datasheet of IS31FL3235 (LED driver), I came across this:

So there is AD pin which when connected to GND, VCC, SCL and SDA gives four possible i2c addresses, thereby allowing me to use four ICs on same i2c line.

Connecting to GND and VCC makes sense to me. How does it work with SCL and SDA? When there is no transaction on i2c lines, SCL and SDA will be pulled up thereby making them same as VCC. How will the chip differentiate between SCL, SDA and VCC?


texts: Electromagnet flux density calculation knowing specs of coil, core and applied voltage?

texts:
Seems to be almost a textbook task from a freshmen class. But I am truly puzzled.

Electromagnet has a coil of tightly wound 100 turns of copper wire around a cylinder core with relative permeability of 600. Size of the core is : width (diameter) 30mm, length 10mm (wire wound around it's wide diameter, it is wider than long). Voltage applied 12v resulting in measured current 0.2A - this should make the wire fully defined for the purpose of solving this problem. For simplicity sake number of the wire layers can be ignored.

How to go about finding field intensity and flux density ?


texts: PIC24F programmed but it isn't executing

texts:
I'm new in PIC MCU. I wrote program for PIC24FJ256JA106 with TFT-320QVT and all were good, but I decided try option "Code protect". I enabled it and at that time I done mistake. I connected programmer VPP/MCLR pin to PIC VDD and ENVREG pins. Also I connected programmer VDD pin to PIC VPP/MCLR pin. After it I tried write a program to PIC but I couldn't. When I connect VDD and VPP pins correct I can write a program to PIC. Nothing happens when I turn on PIC. Before it my program works without any problem.

What's the problem? Code protect or the mistake with VDD, VPP/MCLR pins connect?
I tried disabled code protect but it didn't help.

Pleas, help me!
Yuriy.


texts: What is relation between power deposition and frequency?

texts:
1. What is relation between power deposition  and  frequency in electromagnetic waves?
2. Is it true that even very low power elec.mag.waves can be "dangerous" for long time health if  frequency is high enough?(microwave spectrum)


texts: How to guess voltage ratings and current ratings in capacitor and inductor?

texts:
I have a list of values of capacitors and i also know their material types! But i don't know how to figure out their voltage rating? "Ratings have been removed in the capacitors for this purpose"

Also for my inductors, i have their value.But i have no idea how i can find their current ratings? "Ratings have been removed from the inductor for this purpose"

I have a RCL-METER if that can help me out. I used it to find the capacitance and inductance value!

Thank you!


texts: Do transmission lines induce electric or magnetic fields in towers?

texts: Transmission lines have EM fields around them due to the high amount of current. Do these fields affect transmission towers (metal or otherwise)? If so, would it be possible to estimate the current flowing through the lines by measuring EM fields at the base of a transmission tower?


texts: Working out resistance for unknown BJT circuit

texts:
First of all, excuse me if this question is trivial or common, but I'm trying to essentially self-teach for an upcoming Analog Design exam, so I'm going through older problems that the professor had handed out.
There's a problem that reads: "The voltage sources in the schematic below are +10V and -10V. Explain the use of the circuit and work out the values for resistors \$R_1,R_2,R_3.\$ so that \$V_o = -6.5 V\$"

simulate this circuit – Schematic created using CircuitLab
I've worked out a few things first. Assuming that the transistor is properly biased, then the voltage at the base node has to be \$-V + 0.7 = -9.3 V\$. With that, and the knowledge of the output voltage, all the voltage drops across the circuit are known. I've also noticed that \$R_3\$ acts as a voltage divider
I've tried multiple methods to derive some relationship that links the three resistors, but I'm unsure if my steps are correct. The first I tried was to apply KCL to the circuit, however I end up with a lot of unknown currents, and since the circuit doesn't have an emitter resistor, I can't simplify by letting \$R_e = 10R_2\$ so that \$I_b = 0\$.
I then thought about using a Thevenin equivalent for \$R_1,R_2\$, with \$V_o\$ as a 'source' since it's known, but that breaks the feedback loop that leads to the \$R_1,R_3\$ junction.
Can you provide any hints on how to approach this? I don't want a solution, I just want to understand how to approach it. Thank you.


texts:
I am given a circuit with a transistor and I have to calculate base current. To do that I am using the formula for the linear load:

$$I_c = - \frac{1}{R_c} \cdot U_{CE}+ \frac{U_{CC}}{R_C}$$

So my task:

And the given values:

current boost factor: \$ B = 400\$

\$U_{CC} = 11V\$

\$U_{BE}=0,7V\$

\$R_C=3,3k \omega = 3,3 \cdot 10 ^{3} \Omega\$

\$ R_E = 5 k \Omega = 5 \cdot 10^3\$

\$ R_1 = 55 \Omega\$

\$ R_2 = 7 \Omega\$

So I have tried to use the values to get \$U_{CE}\$.

$$I_c = - \frac{1}{R_C} \cdot U_{CE} + \frac{U_{CC}}{R_C}$$
$$0 = - \frac{1}{3,3 \cdot 10^3} \cdot U_{CE} + \frac{11V}{3,3 \cdot 10^3}$$
$$ - \frac{11V}{3,3 \cdot 10^3} = - \frac{1}{3,3 \cdot 10^3} \cdot U_{CE} $$

$$11 V = U_{CE}$$

Question: Does that make any sense? That would mean that \$U_{CE}\$ always equals \$ U_{CC}\$? What is the right way to solve that task ?


texts: DC voltage gain vs AC voltage gain, are those the same?

texts: Is the DC voltage gain the same as the AC voltage gain un a multistage amplifier? I mean, if the last stage have Vo2 as the input and Vo3 as the outout and Vo3/Vo2=1V/V is it correct to say that that's the AC gain?


texts: Considering trying Atmel SAM and have some questions

texts:
I've been designing boards with STM32 chips for the last couple of years and my curiosity keeps saying that I should try something in the Atmel SAM line of chips.
Most of the time, when someone asks about these chips the response seems to be "go with what you already know" or "neither one is better, depends on what you want to do." I'm not looking for which chip is better, but looking for people's specific experience working with the SAM line. Bonus points for comparisons to STM32 (or other chips).
Questions that stand out to me

Compatibility between chips? - As I've grown with STM32 it's been really nice that when I switch between chips (STM32L0, STM32F4, etc), the pinout and code need very few modifications.
Toolchain - I'm comfortable with C/C++. The dev environment & debugging setup took some time with STM32 since I did not want to use Eclipse. I prefer simple/portable makefiles and such, and I work on a Mac.
SDK - I've gotten used to CubeMX/HAL -- it's not great when things break, but at least I can step through the code to figure out what it's doing. How's the library with SAM? Is the code portable between chips in the SAM line?
PCB Space - The STM32 chip needs a good deal of PCB space (with 0603 parts) as the default configuration requires ~8 decoupling caps + crystal + optional bead. From what I can tell SAM chips need fewer external components to get going.
??? - What else should I be asking about? What are your favorite & least favorite parts of these chips?

My background
I'm a software engineer by trade and work with electronics as a hobby. This means that often when I'm exploring a new chip, I'm not entirely sure what questions I should be asking or what to look for in the datasheet -- besides the rough features. I usually figure these things out as I go, which can be time-consuming. But I'm getting better.
My uses
Most of my work involves battery-powered wearable electronics with LEDs. The basic sensor input is good and ample PWM outputs (I usually populate 4 dedicated PWM outs per board). These days a USB bootloader is a must over a programming cable. I'm building these in small quantities of 10-20 per batch.
Random
I've noticed that Adafruit seems to really like ATSAMD21G18 for many of their boards. Any guesses as to why?


texts:
The conditions for a negative resistance microwave oscillator are (2-port):

\$K < 1\$ (unstable device)
\$Γ_{in} \cdot Γ_g = 1\$ (condition for oscillating input port)(generator side)
\$Γ_{out} \cdot Γ_l = 1\$ (condition for oscillating output port)(load or termination side)

Where \$Γ_{in}=s_{11}\$ and \$Γ_{out}=s_{22}\$ (\$s_{11}\$ and \$s_{22}\$ are S-parameters)

Can anybody please explain the logic behind the 2nd and the 3rd condition?


texts: I have vias connected to the polygon. In the old design (left pic) the vias have annular rings. But I modified few other things in the PCB. I removed unused vias in both new and old design. But now in the new one (right picture) the vias don't have the rings showing up. I guess, it doesn't make difference for the manufacturer? But also, I don't know why is it happening.


texts: Resistor & capacitor are getting too hot

texts:
I made a transformarless power supply with capacitor. When i connect it on ac, it light the leds. But after some second the 100ohm resistor and 470uf capacitor get too hot. Its too hot that i could not touch it then. What's the
 problem . Pls help me.


texts: How do capacitors and inductors behave when they are charging in a circuit with a DC source?

texts: In an RC circuit the fully charged capacitors behave like an open circuit, the inductors, in one of type RL, are taken as short circuits.


texts: Connecting switch-mode supply negative terminal to Arduino GND

texts:
I've got a dashboard which I want to control from an Arduino. I've got the concept but I'm having issues with the power supply of the circuit.
The Arduino is connected to my PC via USB (and it's supply is the USB).

I have some lamps I want to control, as you can see on the first figure.

I've also got some gauges which need amplifiers (figure 2).

To power these I've got a switch-mode power supply (24V DC).

My problem is whether I can safely connect the negative terminal of the supply to the ground of the Arduino (which is connected to the PC). I'd need this otherwise the circuits won't work properly, but I'm not sure it's alrigth to do so.

I tried to measure the voltage between my PC USB port (GND) and the negative terminal of the supply - I got a randomly changing voltage between about -0,15V and +0,15V. But there's a spike when I touch the multimeter to the cables, maximum of ~2,5V. Though I don't know this measurement is correct or not.

I'm afraid if the ground potentials are not the same, I'll destroy my PC motherboard via the USB.

So can I connect them safely or should I try to come up with something else?


texts:
I'm trying to design a mood light system using 4 RGB LEDs which will be powered by an external 9V source and an Arduino for processing.

Link to Fritzing file

Part list:

3 x 2n2222 transistors (NPN)
4 x 5mm LEDs (Common Cathode)(http://www.jaycar.co.nz/products_uploaded/ZD0012%20-%20AL-50-30RGBC-C-004.pdf)
3 x 10k pots
3 x 1k resistors (PWM to Base)

As you can see, what I've attempted to do is:

connect each LEDs common cathode to ground
9V to each (R)(G)(B) collector
Arduino PWM output to each (R)(G)(B) base
emitter to each (R)(G)(B) anode

What I was expecting is that the PWM output of Arduino would regulate the emitters voltage between 0~9V therefore being able to dim the LED with my pots.

What I have instead got is that the voltage is 0.7V short of what the base is receiving from Arduino and the voltage supplied to the collector is being ignored. In fact, I can even disconnect the 9V battery, and the LEDs would still be lit.

From a previous question, I believe this is emitter-follower behaviour?

Is there a way I can re-wire this and get the expected behaviour? Or will I need to get some different parts. I got given the wrong LEDs (common cathode instead of anode) but the shop isn't open for another few days to go get a replacement so I'm trying to make do with what I have.

Please ignore the lack of resistors between the emitter and LED. I have omitted them for simplicity.


texts: What is the difference between 4-, 5- and 6-band resistors?

texts:
I have been buying PSU DIY kits from eBay and I am learning a lot the PSUs that I've soldered together use the LM317 and the resistors used in R1 and R2 can change the outgoing voltage. The LM317 PSU should have no problem going from 1.25V to 30V. I have tried using two different power inputs: one is 12V AC and is only outputting 10.00V DC, then I tried a 15V DC adapter and still only get 10V DC out, so I suspect that the resistor combination between R1 and R2 needs to be changed.

So at this point I am considering getting a breadboard kit so that I don't have to solder in parts; I can just use the breadboard kit to get the parts working the way I want, then solder them in.

This is is a little background information telling how I arrived at the questions I am asking about in this post. I bought a lot of 5-band resistors, the seller penned in what the values are and some are unreadable and have separated from the strip. I went to an online resistor calculator and noticed that there are also 4- and 6-band resistors. This is when the question arose of what the differences are or if the values can even be the same. For example, is there a 4- or 6-band 1k resistor, and if so, what's the difference between them?

I also have put together an LM338 3A PSU module and it is basically acting the same way as the already mentioned LM317 PSU module.

Is the breadboard a good idea for this type of thing, and if so, should I also buy lots of 4- and 6-band resistors?

Any input is welcomed.


texts:
My textbook defines the periodic impulse train and its Fourier transform as:

\begin{align*}
  s(t) &= \sum\limits_{n=-\infty}^{\infty} \delta(t - nT) \\
  S(j\omega) &= \frac{2\pi}{T} \sum\limits_{k=-\infty}^{\infty} \delta(\omega - k\omega_s) \\
\end{align*}

How is that fourier transform calculated? When I try to calculate directly, I get:

\begin{align*}
  s(t) &= \sum\limits_{n=-\infty}^{\infty} \delta(t - nT) \\
  S(j\omega) &= \int_{-\infty}^\infty s(t) e^{-j\omega t} dt \\
  S(j\omega) &= \int_{-\infty}^\infty \sum\limits_{n=-\infty}^{\infty} \delta(t - nT) e^{-j\omega t} dt \\
  S(j\omega) &= \sum\limits_{n=-\infty}^{\infty} e^{-j\omega nT} \\
\end{align*}


texts: LOW pins on ESP32 during flashing and normal boot

texts:
I use ESP8266 in my project. Now I'm going to change to ESP32 (datasheet). For ESP8266, I know GPIO4 & GPIO5 are always LOW, during the flashing or normal boot.
Using these pins can simplify the logic of my board. What pins are always LOW on ESP32?


texts: Injection of EMI to input pins of op-amp in LTspice

texts: In order to observe variation in output from op-amp due to electromagnetic interference I need to inject EMI signal at the input of  a CMOS op-amp.I am trying to do an LTspice simulation on this. Can a voltage source be used for this? Is there any other way to simulate EMI noise in LTspice?


texts: How convert a 3.3v PWM signal to a 5v PWM signal

texts:
I want to drive an array of leds with a transistor, no more than 240mA the things is that im dimming them with PWM works fine with 5v PWM but im having problems with 3v3 uc because with full 3v the leds are not fully bright, I try to solve it using attaching the gate of another transistor to Vout like below but is not working. Any advice?

By not Working im mean that PWM dimming is not working, LED's are always fully on with this approach

Its supposed to drive around 120mA per led array, this are the led datasheet

both transistors are BC337-40 (1A collector current, cant post datasheet link due to reputation)

simulate this circuit – Schematic created using CircuitLab

Wich one can be a suitable "new NMOS"?


texts:
(Image source and more details: circuitio.io)

I am trying to build the above circuit powered by battery alone. Sparkfun HX711 is expensive and hence I am using HX711 bought on Amazon. Here is the documentation

HX711 module has Operating Voltage: 2.7V to 5VDC and Operating current: <10 mA

Sparkfun HX711 has VCC and VDD.

  VCC is the analog voltage to power the load cell. VDD is the digital supply voltage used to set the logic level.
  [...]
  In many cases, you can just short VCC and VDD together. If your microcontroller uses 3.3V logic however, you'll want to connect VCC to 5V and VDD to 3.3V.

(Source: SparkFun - Load Cell Amplifier HX711 Breakout Hookup Guide)

Amazon HX711 has only VCC and no VDD. Therefore, can I connect LoadCellHX711SF VCC to NodeMCU1 3V3 instead of connecting LoadCellHX711SF VDD to NodeMCU1 3V3?


texts:
I am working on a project and have decided that I will design the PCB so that it fits a standard enclosure size, as was suggested here. All electronics websites sell some variety of enclosures, and then there are sites like OKW (and others) which have every variety imaginable.

I don't want to get locked into a specific company or catalog for an enclosure. Just as LEDs come in 5mm and 3mm sizes, what are common standard enclosure sizes?

For example, radio shack has some excellent inexpensive boxes, like a 5"x2.5" for $4. However, Mouser doesn't have any 5x2.5 boxes. The closest box digikey has is 5x2.25. Well I don't want to depend on radio shack exclusively for these things. So what would be a "very common" dimension for a box? For "big boxes" versus "small boxes"?


texts: voice activated circuit with static burst

texts:
I would like to build a circuit that will activate when it detects a voice and when the voice stops to make a static burst sound like a voice activated radio.

What I am trying to do is make a voice amplifier for a Star Wars stormtrooper costume that will sound like a trooper from the movies.

I have an Aker MR1506 voice amplifier but it doesn't have a voice activated capability, it is always on. The microphone has a headphone jack that plugs into the amplifier. I would like to make a circuit the microphone plugs into and then plugs into the amplifier, unless someone thinks a complete amplifier circuit would be a better solution.

The circuit could either detect the voice and add the static burst once the voice stops or it could filter out anything below a certain dB, like breathing, and add the static burst after the voice stops. Anyone have any ideas how I could accomplish this?


texts: CH340G and ESP8266-12e. Doesn't work together

texts:
I've done a USB to UART programmer board. I use Arduino IDE (macOSX)to upload a sketch. If I short RX and TX on a programmer board it works as it should. All I enter in the Serial Monitor it shows me back. But when I try to upload a sketch to my ESP8266-12e it shows me this:
trying to connect
espcomm_send_command: sending command header
espcomm_send_command: sending command payload
warning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed
error: espcomm_upload_mem failed

I connect ESP as it is written in a datasheet for UART. Tried different ways to start ESP described in lots of links available online. Seems like ESP works fine itself. The led blinks as it should. But it looks like it doesn't communicate with the CH340G. If I reset it, it shows strange chars in serial monitor at all possible speeds. I've tried to connect it to Arduino to upload a sketch and it doesn't work with Arduino Nano as well. I've tried other ESPs and they are not working. I've tried connect Arduino to my programmer board and it's not working. My mac sees CH340G serial port. I used the same schematics and components as on Arduino Nano for my programmer board. When I connect my Nano board Arduino IDE uploads the sketches to Nano fine. Also I have an ESP board with a built in CH340G and it  works. But my schematics is not working. I tried to replace the CH340G by a chip from a working nano board and put my one to the board. All chips works fine on the nano board but doesn't work in my schematics. What am I doing wrong?

I've tried to put decoupling caps. But it doesn't help. I've tried esptool in terminal to check the board. It can't connect.


texts: Can't configure ZigBee SZ05-ADV module with X-CTU and can't use XBee API in Arduino

texts:
I have few ZigBee modules to work with but these are not the contemporary digi modules. It has its own firmware installed and has their own terminal program to configure it their way. But every where on the internet, all the tutorials are about digi modules and X-CTU. I can neither make this module work with Arduino XBee API not with X-CTU.

Well, I can broadcast and receive data to a single network using the SoftSerial library but can't change the pan id, or configure the modules from inside Arduino as I can't make use of the XBee API library with this ZigBee module. Anyone has any idea? Or if I try resetting the firmware with the ones available in X-CTU, will it make sense? Provided, I am new to working with XBee.


texts: BJT Constant Current LED Driver - Inverted behavior?

texts:
I'm trying to use build a constant current Led driver, using two BJTs (BC338 and BC547). The idea is to be controlled by Arduino's PWM, for dimming. I'm using the circuit bellow.

The led is a white one, 10.5 mm,  3.3V/30mA. I'm using an Android charger (5V) as PSU. From what I read, the led whould be On when the "control" is connected to VCC, and Off when "control" is connected to GND. But what is happening is the opposite: the led lights full On whenever control is connected to GND (and it glows a little if I touch R1 with my finger) and shuts Off when control is connected to VCC.

I calculated R2 as:

R2 = 0.7/0.03 = 22, where 0.7 is Q2 Vbe and 0.03 is Iled.

If I get this working correctly, I'm planing to replace qthe led with a 1W version (3.3V/300 mA), replacing the R2 for a 2.2 ohms piece.


texts: quartz crystal oscillator applied voltage

texts:
I know that in quartz watches a quartz crystal is used to keep time by counting it's vibrations, caused by the voltage applied to it.

I don't understand if this voltage is DC or AC:

If DC is used, why does the quartz oscillate instead of changing position permanently?

If AC is used, doesn't he quartz oscillator have to oscillate at the same frequency as the AC? If so, then there's no need for the mechanical transducer.


texts:
I have a nominal 5 V rated Schottky diode that I am bench testing in series with a resistance.
In the reverse mode the diode successfully pulls down to the 0.1 - 0.2 V as expected, but in forward voltage, with a 33 kOhm resistor, I am able to get the terminals up above 7 V when I expect it to clamp to the 5 V nominal value.
Why is this the expected behaviour, or is it not?


texts:
We are designing a power supply for a MCU design, which must run directly from mains 230VAC.

We have previous used a "traditional" 230VAC to 6VAC transformer, and used a simple bridge capacitor solution to generate DC supply.

The solution we are working with is the bp5048-15 from ROHM, which would do the job.

www.rohm.com/products/databook/pm/pdf/bp5048-15.pdf

But since this is a non-isolated solution, we get the mains supply to be common with the PCB ground. Which possible could be dangerous, if PCB ground is exposed.

We want to sell this product in Europe in the future, and therefore we need a CE approval.

The CE directive on high-voltage (>48V) is pretty complicated.

What are the safety demands when designing this kind of circuit?

Can it be done non-isolated, or is this a hard way to go?


texts: Delay pulse (trigger) for a variable delay respectively to 0-5V input

texts:
I have a circuit where i detect zero-crossing (Mains EU 230V 50Hz) with opto to arduino(interrupts). Then I need to delay (from 0 to 10 milliseconds) it to trigger Triac gate. but then I need another arduino to tell the first one how long the delay should be.

The variable delay should be like mapping 0-5V to delay time. so 0V no pulse(delay is indefinite) and 5V = no delay and 2,5V delay should be somewhere 5milliseconds.

I am not that good in electronics but i know that AC phase control can be done without first arduino. I have been checking 555 timers but am a bit lost.

So the end circuitry should be zero crossing triggering every 10 milliseconds (have this already with short pulses of 5V) to circuit where I would with PWM or 0-5V set the delay 0 to 10 milliseconds and send again a pulse out (DONT HAVE) to trigger Triac.
Or at least point me to direction I should look into. Is timer 555 the right way or something else?


texts: Why does the datasheet only has one input bias current value?

texts:
There should be two input bias currents, one flowing into or out of the inverting input and the other, the non-inverting input. Their difference is the input offset current. A typical datasheet only states one value for the input bias current. Is that bias current going into the inverting or the non-inverting input? Or is that an average of the two input bias currents? Or perhaps something else no specified on the datasheet?
If I assume \$ I_{B+} = 600 \text{nA} \$ and \$ I_{B-} = 400 \text{nA} \$ then I would get an average value of \$ 500 \text{nA} \$ and a difference value of \$ 200 \text{nA} \$. The calculation matches the values on the specification sheet where input bias current = 500nA and input offset current = 200nA. The leads me to assume that the single input bias current value provided on the datasheet is actually an average.
A similar question was asked here Input bias current in an opamp and its value in a datasheet but I can't find a relevant answer there or elsewhere on the web.


texts:
I would like to know what types of GNSS antennas are on the images below (patch etc.) and also which one is better from the two (if any). They are being sold as "high precision" survey grade antennas.

Photos of antenna internals were send to me by the sellers. Antenna #2 looks like a stacked patch type but I can not recognize type for antenna #1.

Antenna #1 (Buestues/High Gain HG-GOYH7151)

Datasheet #1

Antenna #2 (TOPGNSS/STOTON GN-GGB0710)

Datasheet #2 (dimensions include antenna housing)


texts:
I've been trying to identify a component on a main board for a TV that I believe to be faulty. As I haven't been able to come up with anything that I feel confident about, I'm hoping to get some guidance.

I believe the package to be a SOT23-3.

The markings look like 22P W8.

22P might indicate a JFET and W8 could be a zener diode.

It's located in the path between the +12V coming from the PSU going to 4 pins on the LVDS connector going to the 12VIN on the T-Con board.

There seem to be a crack in the package and the voltage going to the LVDS is unstable and changes when pressure is put on the component. So I don't know what use measurements of the component will be.


texts: Need a continuity LED for high voltage capacitive discharge rocket launcher

texts:
I'm designing a capacitive discharge rocket launcher. The reason for the cap discharge is to ignite a series of many devices at once. I did not want to switch the HV with the momentary pushbuttons alone so I decided to drop down to 5v and use transistors. For simplicity I only show 4 buttons. I wanted to add continuity LEDs to show a connection to the firing ignitor and I've placed them in the schematic as shown, but this will not work with the transistor. I'm stumped and need some guidance.

Please note that this is a work in progress and some areas in the circuit still need brainstorming. I'm still relatively new to designing circuits so any help or suggestions with any part of the circuit would be appreciated. If something looks wrong, please tell me.


texts:
I was reading about the series termination techniques.
I have seen many schematics with 33E series termination for clock signal. Can anybody please let me know why 33E is used & what happens if increase or decrease the resistor value & How the resistor value is calculated.
Thanks in advance.


texts: Measure leakage inductance of flyback transformer with multiple secondary windings

texts:
I have a transformer consisting of one primary winding and 3 secondary windings. Now I want to measure the leakage inductance at the primary side, so I need to short the secondary windings. Most of the literature I have read, there is only one secondary winding so it's pretty straightforward how to short the secondary side. But now, I have 3 windings at the secondary side, I am considering of 3 possible ways to measure the leakage inductance at the primary side:
1. Short 3 and 4, 5 and 6, 7 and 8
2. Short each winding one by one while leaving other windings open, e.g 3 and 4 shorted, 5 and 6 open, 7 and 8 open, etc.
3. Short 4 and 5, 6 and 7, 8 and 3.

Assume that my short circuit is perfect, what is the best method to measure? Thank you.


texts: How to determine the practical constant current rate of charging phase of a Lithium battery?

texts:
As discussed earlier, terminal voltages would never exceed the CV value (4.2V for Li-Ion cell) while charging:

If that's the case, the CC value should be the current value at the time the terminal voltages just reached to the CV value.

Could we precisely determine the exact "Constant Current" value (the Current Limit value, actually) of a given Lithium battery by the following procedure:

Determine the battery chemistry to determine the CV value (eg. Li-Ion battery, 4.2V/cell)
Use its capacity value (or make a safe assumption) and use 0.5C to start charging.
At the moment the terminal voltage of the battery is just reached to the CV value (4.2V for Li-Ion), increase current limit of the power supply to the point that the actually drawn current is not increasing anymore.
The actual current at this moment is the CC value.
To fine tune this determined CC value, repeat the steps from #2 for one or two more times.

Is above procedure correct for determining the exact practical CC value of any Lithium (based) battery?

Rationale

In order to safely use any Lithium Ion (or LiFePO4) battery for a custom application (device), charging characteristics should be determined if it is undocumented (like a cell phone battery).

If this is an appropriate procedure, then we could verify a battery follows its datasheet specs.


texts: Cannot figure out resonance of an LRC circuit

texts:
this is my first time here, nice to meet you all.

In one of my classes we are studying the resonance of an LRC Circuit where the C branch is in parallel with an RL branch.  This circuit is driven by a function generator made 1Vpp sine wave, and we are looking for the natural frequency, and two corner frequencies (where Vo/Vin = 0.707)

The setup of the circuit is like this:  the signal goes through a 1k resistor, then at the opposite side of the resistor, the node splits into 2 parallel branches, where 1 has a capacitor of 0.011uF and the other branch has a 51 ohm resistor in series with a 9.8mH inductor.  The circuit can be seen here:

http://jmp.sh/v/C8E5a0YXEAAXY2VPxwP7

I set the transfer function equal to 0.707 for Vo/Vin but I ended up getting s=jw=16060+-93637i.  I do not understand this result, mainly because we have barely even touched on transfer functions and solving for resonance this way.  How can I get from my result (if it is even correct) to the angular frequency and thus the actual frequency?

You don't need to solve it for me, just a gentle nudge in the right direction would help tons.  I asked the professor but I think I'm on my own for this one.

Thank you all

C


texts: How do I signify an off board connection in Altium?

texts:
I am designing a circuit board or hat for a raspberry pi 3 with the pinout below:

I have a schematic symbol that is defined just as the raspberry pi header is (pin locations/numbers/names). It has multiple ground pins, which are all connected to their respective pins on the footprint.
When I am routing the PCB:
I want to tell altium that the GND pins are all interconnected on the raspberry pi, and so they don't need to be connected on my PCB. How can I do this?
Another way to put this:
How can I tell altium that parts connected to net [GND] on my PCB need to be connected to pin 6 [GND] OR pin 9 [GND] OR pin 14 [GND], but not all of the [GND] pins?
I dont want to run traces between all of the separate ground pins on the raspberry pi header while routing, but at the moment that is the only work around I can think of.
EDIT:
I say not all grounds need to be connected together because not all of them are actually used. I wanted to do this because I wanted to be able to decide which pins were actually going to be used in the PCB design stage, and not have to swap between PCB and schematic to decide which pins to be connected.
An example:

the ground conected to pin 30 above is not normally connected to anything when this board is in use. It is broken out for debugging purposes. Being on the edge of the board, there is no reason to try to connect it to another ground, since it is only used when the raspberry pi is in use.
Thanks to desqa, I know the name of the characteristic I was looking for- Jumper IDs - and I was able to get it working in my design.


texts: Microwave oven with no heat, Bad design or wrong component choice?

texts:
Few days ago, my Magic Chef MCD990B microwave oven magically passed away randomly and so suddenly that I didn't even have time to say goodbye, not that I have used it heavily or considered it as my friend, but still, it was a sad day for me.

Today, I finally got off my ass (It's just an expression, stop being so sensitive), and took it apart, not trying to kill myself because I am sad or anything, although it could be deadly if done incorrectly, but trying to save the environment, and it's not like I can afford to buy another one of those thing anyway.

Since I am not an expert in microwave oven and I hardly even know how to boil a pot of water, I asked my old girl, ms.google. According to her, 3 main reasons that a microwave oven appears to work, but produces no heat are: 1, bad high voltage diode; 2, bad door switch, and 3, bad magnetron.

While I know what a diode is and how it works, the high voltage part of the description scared the hell out of me, so I decided to follow the instructions given by a random gentleman from Youtube to test that diode, and it turned out fine.

My oven comes with 3 door switches, and I tested all of them using my old meter, and they turned out fine too, so as the magnetron. I also took apart the main board and checked the 12v relay and every things looked good to me.

Finally, after 2 hours of messing with this dead microwave oven, I though I had figured out what the real problem is, and I was right. The problem for this over-priced oven is not from a 10 cents badly made capacitor, but from over-used of bad connectors. Oxidation have formed on all of those 3 latch-door switches due to the high current passing them.

Surprisingly, the microwave oven is a very simple device. While I don't have a circuit diagram for this, I can tell that the main power for the transformer go through all 3 of these switches and a relay in the main logic board, so there are actually 4x2+2(for transformer)+2 (for the power input)= 12 of those kind of haphazardly connected connectors to deliver the high current to run a high power microwave oven. To be fair, the connector for the relay is pretty tight.

Question 1, My oven is less than 1 year old. Are those switches bad design or planned obsolescence or something else?

Question 2, I know safety is very important for these kinda of oven, so they use 3 door switches, but would it make more sense to use low current switches and use the main logic board to control the power? They are using a relay to control the power anyway.

Question 3, I have used sand paper to scratch off the oxidation, but I can tell oxidation will form soon, since those connectors are very loose, and I think I can actually hear sparks coming from the oven once microwaving. Is there a way to avoid oxidation? Soldering is not an option, since the space is so tight.


texts: VGSS and Max VGS and VGD in the actual circuit - relation

texts:
I am using DMD2005 in one of our designs.
In one of the circuit,
This MOSFET is used as a simple inverter where Drain pulled up using 10K to VCC which can go up to 15V peak (rarely, typical always stays @ 13.2V),
Source is GND,
Gate will be driven either 0V or 3.3V.
In this case, sometimes we see VGD is up to -15V (worst case for short time).
Is the Max Voltage VGD = -15V will be problem for this MOSFET (Can i use VGS max specification to compare VGD worst case voltage).
But in actual circuit i see VGD can go upto +/-12V in some cases.
VGSS is Max Gate to Source voltage with Drain and source shorted. Whether we can take this VGSS spec for Max VGD in actual circuit (VGD in actual ckt < VGSS)


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

In the book, he often uses the term "origin pole". This is what I think
I understand about it so far:

When a transfer function contains an "integrating" element, that element
represents an origin pole. An integrating element is
a denominator element with an \$s\tau\$ factor on its own, one that is not
part of a \$(1 + s\tau)\$ factor. This is consistent with the idea that
the Laplace transform for an integral is \$1/s\$. \$\tau\$ is commonly an
RC time constant. This would be an example of an integrating element:

$$\frac{1}{sR_2C_2}\text{ from, say, }\frac{(1+sR_1C_1)}{sR_2C_2(1+sR_3C_3)}$$

Mathematically, an origin pole has infinite gain at DC (\$s = 0\$), from which
"point" the gain declines at 20dB/decade. In practice, this rise to infinity
is halted at some point, such as when the available gain of the op amp is
reached.
(Not completely sure about this bit): The gain curve of the origin pole, if
unaffected by other poles or zeros, crosses 0dB at \$\omega_o\$, the
frequency of the pole, \$\frac{1}{2\pi\tau}\$, which is perhaps typically
\$\frac{1}{2\pi RC}\$. This is markedly different than a "regular" pole, whose \$\omega_p\$ is the point of a downward inflection in the gain, a so-called breakpoint.

Before starting the book, I thought that all poles were located at a 3dB breakpoint and looked like this, but maybe I slept through the day origin poles were mentioned in class :) :

so this idea kind of threw me for a loop (no pun intended :) while I've been working to make sense of the book.

So here's my question:

Am I understanding this correctly so far?
Do other folks use the term origin pole or is it something Christophe has
introduced? The term doesn't seem to pull up too much on search.
Is there anything else interesting about origin poles that I and other
curious readers yearning for knowledge might like to know, particularly in the
realm of control loop transfer functions? :)


texts: What is a 3 wire type cross linked serial cable?

texts:
I'm trying to use a controller which uses Serial communication with the PC. The documentation says I need to get a 3 wire type cross link serial cable.  Is this a null modem cable?

The following image is from the documentation.


texts: 24v DC solenoid coil with LED indication getting failure sometimes in reverse polarity

texts: I am giving power supply to 24 v (DC) solenoid coil plug with LED, positive from pnp transistor board and negative directly from the smps. when the pnp board energise the output terminal, the coil plug gets short circuited and also it makes the transistor also failure. I think it happens when i am giving the reverse polarity. But it does not happen to all the coil plugs. some other coil plugs with LED, also reverse polarised but it is working good. so, someone help to understand what makes the LED failure?.


texts: What type of solder should be used to assemble Adafruit cobbler

texts:
I'm a complete noob at soldering. I want to assemble Adafruit's Raspberry Pi Cobbler as shown here: http://learn.adafruit.com/adafruit-pi-cobbler-kit/solder-it

These instructions fail to mention what type of solder one should buy. Any suggestions for solder for electronics?


texts: What is the difference between a Barkhausen-Kurz tube and a transmitting triode?

texts:
So I have 2 transmitting triodes in my VT collection:

GE GL-592 tube
Amperex 5868 tube

Both of these were marketed as transmitting triodes. So does a transmitting triode work as a Barkhausen oscillator? For the uninitiated, a Barkhausen oscillator is a specialized type of triode which acts as a reflex oscillator. Both the cathode and anode are held negative and the grid is held positive. I noticed that the Amperex 5868 tube is a radial beam triode with a very thick anode that completely shields the cathode. I still need to find a socket for it so I can test this effect using a DC power supply and an oscilloscope.


texts:
I am trying to understand a problem I did once with capacitors.  I am not a native English speaker so I am translating it, I hope you can understand it:

  A capacitor C2 is charged with 10V, then, it is connected with C1 and
  C3 which are discharged. After that we connect points A and B with a
  cable (resistance 0). Calculate the final charge of each capacitor.

By Kirchhoff and knowing that V = Q/C I know that:

$$V_{C1} + V_{C2} + V_{C3} = 0$$
$$\frac{Q1(initial) + q}{C1} + \frac{Q2(initial) - q}{C2} + \frac{Q3(initial) - q}{C3}$$

Here Q1(initial) and Q3(initial) is 0 because they are discharged and q is the charge which is moved when we connect A and B.

I understand this:

$$\frac{Q2(initial) - q}{C2}$$

Because C2 loses charge to charge C1 and C3, but why C3:

$$\frac{Q3(initial) - q}{C3}$$

Also loses charge if it is being charged? I know the result of q is: $$31.25\mu C$$

So the equation is correct but it doesn't makes sense to me!


texts: What specific parts of a radio receiver use power? Does receiving the signal need the battery

texts: Does a radio receiver need power from a battery in order to receive a signal, or is the power just used to amplify the signal? If you wanted to simply detect a radio signal of a certain frequency (not demodulate or amplify the signal), would an antenna and a tuner be enough?


texts: When supply fan VFD starts up it causes communication problems for my energy management controller

texts:
We have an energy management system that controls the air handlers for a building. I have one unit that when the supply fan VFD starts up it cause the unit controller to start having communication issue. The controller starts to reconfigure and drags down all the other controllers. The controller is fine, we have replaced it with a new one just to make sure. It sounds like its electrical noise causing the issue. Any ideas on how I can correct the problem?

Thanks in advance,

Henry


texts: What would I use to distribute power in my project?

texts:
I want to power 10 SG90 servos, which each operate at 4.8v or 6v and need over 1 amp in order to start and use 700ma max during operation (I think). When I look at a kit like this (https://www.amazon.com/gp/product/B073ZC68QG/) on Amazon, it says one of the questions is as follows:
Question:What is the maximum current rating on the power supply module?
Answer:The Power Supply Module Maximum Output Current: < 700ma
Does that mean each servo will only get under 700ma and not be able to start? If so, what tool should I use to distribute power to parts in my robot?


texts: Multidrop RS232 - Diode selection and doubts

texts:
i'm currently using this reference schematic to wire up 10 RS232 slaves in a "multidrop" configuration (The slaves are some ATMEGA328P with MAX232 Trancievers in order to make a real RS232 network).

I have some doubts regarding the diode to put on TX line of slaves: i've tried using LL4148 (Datasheet here) but nothing works, the slaves will not work as expected.
So, i've taken a BZX85C5V1 Zener diode and i've replaced the LL4148, now the slave works as expected: receiving and sending messages to the master.
What i'm missing? maybe i've chosen a wrong diode (LL4148)? which diode i can use in this multidrop serial network configuration? Why 5V a zener (BZX85C5V1) works?


texts: Op-amp output oscillating on one of two (virtually) identical circuits

texts:
I have a board that connects two analog sensors to an ADC via several op-amps (all MCP6042).  One circuit is behaving as expected but the second (virtually identical) circuit on the same board is showing severe oscillation on two op-amp outputs.  I don't have much experience with op-amps so I'm not sure how to approach debugging it.  Both circuits share the same power supply, ground plane, and ADC.
I've already tested for connectivity/shorts, reflowed the joints, and cleaned the board.  Any ideas what could be causing this behavior?

The yellow trace is the clean output from the first circuit, blue is the same for the second (problematic) circuit.  Both circuits were probed at the output of the final unity-gain stage (U3.1:B, pin 7); probing the output of the previous stage (U3.1:A, pin 1) gives similar results.

Trace
Measured values

I'm seeing similar oscillations on the output of the second circuit's first stage (U2.1:A, pin 1) as well; these are mostly damped though by the RC network after it (R4.1, C2.1).
Here's the schematic of the problematic circuit.  It's the reference design from the sensor's manufacturer.   The only difference between the working and wonky circuits are the values of R2.1, R6.1, the position of the two Bias +/- jumpers, and the actual sensor used.

All parts on the problematic circuit (shown) have the suffix .1 (e.g. R6.1 or U3.1:A); those on the working one have the suffix .0.
On the working circuit R2.0=2kΩ, R6.0=100kΩ, bias=-, U1.0=SPEC 110-109 (CO sensor).
On the wonky circuit R2.1=16.2kΩ, R6.1=499kΩ, bias=+, U1.1=SPEC 110-407 (O3 sensor).
The two circuits are otherwise the same.
Bias jumpers XY1.1 and XY2.1 are connected pin 1 to 2 on the working circuit and pin 3 to 2 on the troublesome one.
My understanding of the sensors' design is that when the gas is present a current flows out of the sensor's W1 and W2 terminals.  Current flows into terminal C to replenish the supply of electrons and terminal R is used to monitor the charge level within the sensor (i.e. a feedback loop).


texts: Voltage measurement at different adc ground

texts:
I'm trying to measure a voltage drop across a resistor divider with a supply from ldo. The single ended adc is connected as follows. Will the adc readings give the expected readings if the gnd1 and gnd2 are not connected?

Update added November 27:

Thanks a lot from your inputs.

So I've managed to make this work by having GND1 = GND2.


texts: Connection For simulation touch using 1ch relay

texts:
http://gameautomators.com/book/Electronics/4-simulation.html

Hi
here is a reference to make a touch simulation with rpi and 1ch relay
I can't understand how to connect gpios with relay.

There are DC+ / DC- / Ch1 / NC / NO connectors in my relay.(OMRON G3MB-202P)

PLZ SEE attached image.

Green GPIO(pin4) : DC+

Blue GND : NC

Red GND : DC-

Green Output : Ch1

is that right?


texts: Is it possible to split micro USB to USB cable so two cables (data + and data -) go to the PC with USB and two other power cables go to power brick?


texts: Compact fluorescent lighting and single phase motors

texts: I have about a dozen compact fluorescent light fixtures in a sandwich deli store kitchen area and about a dozen more in the front of the deli.  When the vent fans over the griddle are turned on the compact fluorescent lights dim quite a bit and remain that way until about a minute after the vent fans are turned off.  What would cause this and how do I correct the problem


texts: Can I use a high power (2-6 kw power supply) synchronous buck converter ( at least 85% efficiency)  to work as a welding machine that outputs around 10 -20 VDC and 100 -300 amps? If I can, what is the best kind of transistor for this application? ( igbt or a mosfet)


texts:
I am trying to run a low-power, battery powered Arduino on a breadboard. I followed these instructions exactly:

https://www.openhomeautomation.net/arduino-battery/

I uploaded the "Blink" sketch to the ATMEGA238P-PU from another Arduino then I installed the chip on the breadboard and connected all the components exactly as described. The led is off and not flashing. See the image below:

Things I already tried:

Had the ATMEGA + led + 220 ohm resistor installed on the Arduino Uno board. The led starts blinking as expected, the ATMEGA chip itself is functioning as expected.
Connected the led + 220 ohm resistor to VCC and GND. The led lights up which means both the led and the resistor are in good shape.
Swapped every component out with another identical one, one at a time. That did not help.

What else can I try to track down the problem? If anyone has any suggestions, it would be greatly appreciated!


texts: What size capacitor do I need to reliably close a 1" US Solid motorized ball valve?

texts:
I am making a water feature that will involve a stream fed by the basin of a fountain with a pump at the end sending water back into the fountain. To control the water flow rate through the stream and prevent flooding, I intend to use this valve controlled by an Arduino connected to a water level sensor. The nice thing about motorized ball valves is that they have very little head loss and can be left in a partially open position to throttle fluid flow.

For safety, I would like the valve to be able to fully shut from fully open in the event of a power loss. US Solid makes a variant of this valve with exactly this capability, unfortunately it does not have the ability to remain half open. Their documentation says the auto-return valves store energy in a capacitor that is used to shut the valve when power is cut off, but they don't give specifics on the size. I'd like to do my own custom set-up with the 3-wire version and my own capacitor, and I'm figuring out what size I need.

Their specs say it can operate in the 9 to 24 volt range, takes 3-5 seconds to close, and can draw up to 2 watts. Taking the worst case, 5 seconds at 2 watts, I need to be able to deliver 10 joules of energy between 9 and 24 volts. Taking stored energy as 1/2CV^2, I calculate that if I'm going from 24 volts to 9 volts, I need 1.3F of capacitance, or if going from 12V to 9V, I need 6.7F. A supercapacitor might work for this, but the closest I have been able to find with anything close to these specs that is not a complete beast is something like this one from Kemet. That one sells for $62, and given that the auto-return valve itself is only $45, I doubt that's what they're using.

Can anyone give me some guidance on selecting the right capacitor for this valve? Alternatively, I suppose I could use a rechargeable 9V battery as the backup power source, but then I would need to build a battery charger into my circuit, and that adds a whole other layer of complication as well.


texts: How to implement sealed line noise-proof method in this circuit?

texts:
I am trying to generate -8.5V from my 5V battery. I found a suitable IC for my purposes. The datasheet of the IC (circuit schematic is available below) says

  use sealed line noise proof method

(for pin 10). This IC will be mounted on a PCB and I'm not sure how to do what they are asking for.

Can someone guide me through this? What exactly am I suppose to do?


texts: AT89S52 switched mode IO Pin 2 not setting to ground

texts:
I am designing a simple circuit with AT89S52 micro controller. I set the I/O pins as high and when the switch is pressed will get connected to ground. And in my program I check for I/O pins as 0 and on 0 will set pin 1.5 as high and the LED will glow.

But the pins 2.0 to 2.7 is not working as expected.  These pins are always high even the switch is pressed.  Kindly check the attached image and suggest me if anything is wrong.


texts:
How is the output of a monostable multivibrator affected if the trigger pin is kept at a negative voltage (0V)?
The upper voltage reference comparator will change its output to logic 1, while the lower reference comparator is already at logic 1. As a result the input to the RS flip flop goes into forbidden state (R=1,S=1).
What happens at the output?


texts:
We are attempting to build a coilgun with multiple coils, and each coil needs to be energized and deenergized at precise time intervals. For cost (and inexperience) reasons, we are considering using an Arduino Uno for this task. Our questions are as follows:

How quickly can the Uno toggle a pin between states?
How consistent is the timing?
Is there a better option, keeping in mind our inexperience and lack of funds?


texts: Does a battery's voltage fall to 0 V when it has run out?

texts:
So it's that time when I have to replace my mouse batteries (2 x AA, 1.5 V each). I used a voltmeter to check how much voltage there is left. Turns out it measures around 1 V each for the 2 batteries.
I assumed that when a battery runs out, there's no voltage left at all. But in this case, there's still 1 V left.
Can anyone explain why this is the case?


texts: Help in calculating resistor values for AMS1117-adj

texts:
Wish to use AMS1117-adj to create Vin 5.0V, Vout 1.6-1.8V for 1-3 LEDs drawing 80ma each.

My calculations from the datasheets resulted in R1 and R2 values so low that they pulled more current than the load.

Used on-line calculator with the result about 3.3V, even after doubling and halving values of R1 and then R2.


texts: How much power (in watts) can I get from my house outlet?

texts:
Suppose I have a PV panel. On it's peak time it produce 7 A with 14 V. So to find out how many watts I get from it I would simply apply this formula:

\$P = I \cdot V\$

So, by applying above formula:

\$ P = 7~A \cdot 14~V = 98~W\$

So, I would get 98 Watts of power, right.

Ok, here are the diagrams how I took these reading of amps and volts:

Now, If I calculated the power coming from my wall socket by this same method, I could easily measure voltage but when measuring current, the short circuit will cause (because resistance of ammeter is very low) and BOOM! (I think so, this will happen). As current from PV was pretty less than the current from outlet so I assumed it would be safe.

So, basically my question is that there are standard 220 V in my wall socket, how much maximum current can I get from it?

Mentioning of 220 V reminded me that some countries have 110 V house supply. What is the reason for it? What's the benefit of having 220 V over 110 V or 110 V over 220 V?


texts:
I have trouble understanding conversion between different data types in VHDL and needed help with conversion to `STD_LOGIC_VECTOR' type in VHDL.

I want the code below to be synthesized such that it can be used on real hardware.

For now i have the code setup as follows

signal   VREF  : real := 65536/3.3;
constant SIG   : real := 2.33;
signal TEMP    : unsigned(15 downto 0);

signal WORD_A : STD_LOGIC_VECTOR(23 downto 0) ;
signal SIG_A  : STD_LOGIC_VECTOR(15 downto 0);

BEGIN

TEMP <= to_unsigned(VREF,16)*to_unsigned(SIG,16);
SIG_A <= STD_LOGIC_VECTOR(TEMP);
WORD_A <= "00110000" & SIG_A;

I used the following libraries : IEEE_NUMERIC_STD.ALL, IEEE.MATH.REAL

I get the following error
ERROR: [VRFC 10-1471] type error near VREF ; current type real; expected type natural

Any inputs is appreciated

Thanks


texts: pBlazSim Picoblaze simulator - Trouble Getting Started

texts:
I've been trying to simulate my Picoblaze code with pBlazSim, but I'm having trouble with the lack of documentation. Am I missing something? Could someone point me in the right direction?

Edit - I've been confused as to how to add software emulation of external components - there's references to pBlazIDE, the previous software, in ug129 from Xilinx, but I'm finding a complete dearth of information on the newer software. Using pBlazIDE, single stepping the code we have works just fine, but doing multiple runs having to switch inputs on and off by clicking a box is really frustrating after a few hours - we'd like to automate that portion, using the 'newer' pBlazSIM, but are having trouble finding a community of practice.

I apologize the question wasn't more fully worded - Christmas is distracting.


texts: how to use a photodiode to count water drop

texts:
So, I am doing a project in which an IR led is emitting light and opposite to that IR led is a photodiode (conventional IR photodiode - which can be found on normal store).

Between them is a long glass tube with 2 holes on the left and right (to plug the photodiode and led)

Whenever a water drop fall throught the tube , the photodiode signal is changed of course and by detecting that change we can count how many water drops have passed through.

What i want to ask is, How to use a photodiode to do this task- I mean which type of circuit should I use for the photodiode? A transimpedance amplifier (TIA) is suitable or not?


texts: Short circuit when probing live ATX power supply primary section with voltmeter

texts:
I was probing around an old ATX PSU to inspect voltage levels in the primary section. The first 15 minutes went smooth (bridge rectifier inputs, big caps, Power IC Vcc, etc..) but as soon as I probed the solder pads of the large coil circled in red in the picture, a short happened with the usual bang, sparks and smoke.

First question: what is that large coil (Hi-Pot) connected to the primary side? Is it part of the EMI reduction circuit?

Second (probably stupid) question: my DMM has 10Mohm input impedance when used as voltmeter. How can I cause a short like that if I am careful to ensure that meter probes do not touch one another and that I do not short any PCB tracks with the probe tip?

I am extremely careful when I work on energised circuits, so I am rather annoyed by what happened as I may make the same mistake again if I do not understand exactly what I did wrong.

A last question related to general safety: is there any difference between using a 1:1 (230VAC -> 230VAC) isolation transformer vs connecting the appliance to be probed directly into the mains using a lead without the earth wire (or with such earth pin isolated/disconnected)?

Thanks to the community for your precious help.


texts: Computing "approximate" absorbed power for an AC motor of a pump from missing data

texts:
I have an year's worth of time series data for a pump: a lot of data are missing. I would like to estimate the trend of the absorbed power with time. I don't need to get an accurate estimate of power: I just need to have an idea of the power trend during the year.

I forgot how to estimate absorbed power for an AC motor. For a direct current system, clearly electric power absorbed by a system with one input and one output is equal to the product of the voltage differential between input and output, times current at input or output (they are equal). In my case (AC current) I have the following sensors measurements, at regular intervals in time:

Amps_out_A, Amps_out_B, Amps_out_C, Volts_out_AB, Volts_out_BC, Volts_out_CA, Amps_in_A, Amps_in_B, Amps_in_C, Volts_in_AB, Volts_in_BC, Volts_in_CA

I think these are currents in input & output at the three phases (A, B, C), and voltage differentials across the phases (AB, BC, CA), again for input and output. The problem is that many of these data are missing. Precisely, all measurements for Amps_in_A, Amps_in_B, Amps_in_C, Volts_out_BC, Volts_out_CA are missing. Is it still possible to estimate the absorbed power with the other measurements, and if so, how?

The sensor measurements file contains also other sensor measurements. The names of all the variables for which at least one measurement is available are:

DataKey
WellID
TimeGMT
Freq
FreqSP
Pip
Pdp
Ptbg
Tin
MTemp
Xvib
Yvib
Amps_out_A
Amps_out_B
Amps_out_C
Volts_out_AB
Volts_in_AB
Volts_in_BC
Volts_in_CA
LastSD
DataSource
XRatio


texts: Equivalent electrical model for induction motor

texts:
For those people who are looking for induction induction motor SPICE model, please follow the link LT SPICE tools and applications

I'm trying to understand the model characteristics and from the image attached, I don't understand what the terms and where they came from:

V=-Np*V(w)sdt(V(Yr))
V=NpV(w)*sdt(V(Xr))

The constants from the below parameters are hiding somewhere in the model and I couldn't find where they are.

.param N=475
+Bs=1.8 Br=0.5 Hc=40
+A=1m5 Lm=0.2 Lg=1m5

I'm designing power electronics for 3-phase 3KW SR motor and I'm trying to model an equivalent SR motor circuit that can be used in LTspice to simulate the results. For simplicity, I'm trying to first simulate only 1 phase of the motor. To do that I'm only using upper circuit model with input X and not considering the secondary phase with input Y(assuming this is right way) from the below image. But the equation V=-Np*V(w)sdt(V(Yr)) has parameters from the secondary phase. How to define the model without secondary phase?

Thanks in advance.


texts: Pinout of Audi 2008 A4 Quattro 3.2L MMI to iPod?

texts:
I have came across an Audi A4 2008 Quattro 3.2L, and in the glove compartment it an iPod dock. I took it apart and behind the iPod dock there is a PCB which connects to the ipod connector (which mounnted on another PCB) via 10 pins. This board has the following information:
DEICE42143 V2R6-3 Zold
SNZ0043525 F.-Dat 31/7

The car has a 12-pin connector (only 9 are populated) which is connecting to the above PCB. I looked all over the place for schematics/pinout of this module and did not find any information about it. I just wanted to hack in an AUX to it...

Anyone has any idea how I can figure out which pins are which on the 12 or 10 pin connectors?


texts:
I'm trying to connect a device to my laptop using a TTL to USB converter like this one

but it doesn't works

so I tried the following configuration

(USB to Serial, RS232 to TTL and then to the device)

And works perfect.

Both (USB to Serial and USB to TTL) are using the PL2303 driver.

The question is why the USB to TTL didn't work? it uses a different protocol?


texts: Regards. My question is why this regulator uses 4 mosfets (which is the role of the lower mosfet) .I do not understand why two lower mosfets are needed (because when the signal comes to the gate b++ trece is connected to ground through mosfet resistance ) the output voltage will drop


texts: Analog to Digital Converter and Negative Voltages

texts:
I'm using the ADC on an ATtiny24 to record a AC signal. The ADC has a range from 0-3.3V. I'm using a precision rectifier to get rid of the negative portion of the signal. I've attached a picture of the circuit I'm using for the rectifier. I'm using an LMC6484 as the op-amp with 3.3V to the V+ rail and 0 to the V- rail. I'm using 1N4004's as the diodes and 10k for the resistors.

My logger is able to graph the waveform of the rectifier very well. BUT the oscope shows that the output of the rectifier  varies from -0.5 to 1V. But my micro shows a signal with the same waveform that goes from 0-1.5V! If I replace the precision rectifier with a simple diode/resistor combination, I get a waveform that varies from -0.X volts to Y volts (depending on the input through the function generator). The micro follows the shape of the waveform correctly but the voltage range is from 0.X to Y volts.

I always have a little bit of a negative signal even with the precision rectifier and when I graph the results through my logger, it appears that the largest negative value has been moved up to zero, so I seem to get a larger range than the input.

Is this a result of putting in negative voltages into my ADC? Does it take the negative voltages, set that as 'ground' with respect to other voltages?

I've input positive voltages into the logger through a power supply, and it reads those voltages perfectly! It follows the shape of the waveforms very well too. The only problem seems to be the range. I'm completely lost.


texts: Measuring time using an STM32F407VGT6 microcontroller

texts:
I'm using a custom board for charging and testing batteries.
Its 'brain' is an STM32F407VGT6 microcontroller.
I'm developing in Ubuntu (14.04.2 LTS), using ChibiStudio (ChibiOS/RT 3.0 development branch and Eclipse Kepler).
While in charge mode, I need to see how much time has passed since I initially started charging the battery. I'm having trouble with writing the necessary steps required for the time measurement. The microcontroller has an internal real-time clock (RTC). It also has timers. And ChibiOS has a time measurement function. However, I went through the documentation, researched online, but I still cannot make it work.


texts: Lolin32 using 6V power supply to power the board through the JST Ph-2 pin connector

texts:
I'm using the Lolin32 microcontroller board and noticed there is a JST Ph 2-pin connector which takes a lithium ion battery. I noticed a chip (MCP73831) used to automatically recharge the battery if it reaches a voltage below 4.2V.
Can I connect a 6V external power source from the wall directly into this connector to power the microcontroller? If I have my laptop plugged in at the same time, can I potentially damage my laptop or the power supply?
This chip doesn't mention non-battery external power supply use, and am wondering if this is common practice or safe to do.
Another thing I noticed is that if my power supply goes down to 4V somehow, it seems like my USB cable would pass current to the Power supply which could potentially break my laptop because it will try to push too much current or will break the power supply?
One thing to note is that I am powering a DC motor in the circuit as well with a servo motor, so these might pull my voltage down from 6V to a lower voltage.
Thank you.


texts:
So I'm playing around with an idea, but I'd like a good, compact way to power it.

In the past I've used old wall warts to provide the power. Just find one with the power output I need, solder the AC power to the plug with some heat shrink tubing to insulate it, and then take the power output and put it where I need.

The problem with that is that they are bulky and hard to fit into a project box, and I'm hoping to have something a bit more professional.

So I started to do a little research and found this: AC/DC Converter, and it looks like it would do what I want in a very small package.

To reiterate, I want to be able to run a couple AC leads in, get DC power out to power circuits and stuff.

Edit:
Some details. I'm looking for a pretty compact solution that provides ~5vdc, ~.2A

The smallest wallwart style adapter I know about is the iphone adapter, and it's a little big. Something small that could be used to power a ESP8266 or Arduino ATMega without having to have a giant enclosure.

I was hoping to find something with a form factor similar to the one in the link, but part of my question is if that's even a possibility.

Edit:

Found this.

https://www.instructables.com/id/ESP8266-Wifi-Switch/

This is very similar to what I want to do, and they use a HLK-PM01 to turn AC power into 5V DC power, and a LD1117V33 change the 5V to 3.3V.

Besides the size, another problem I have with wallwarts is that they aren't consistent. Out of the dozen wallwarts I have laying around, I don't think I have 2 that are exactly the same.
Having a solution where I can order a handful of components and get consistent results is kind of a big deal.


texts: Trigger 5V relay to turn ON OFF with voltage

texts:
Picture above shown an automatic watering timer using solenoid. The timer inside this device will turn on dc motor forward/ reverse for a short period to trigger the solenoid mechanism based on time set. Now, Im trying to using the timer from this device to trigger a relay to turn on a dc water pump instead of solenoid from the same output (black and red wire). Im guessing that this can be achieve with something that can trigger ON or OFF relay when voltage applied.

While searching on the internet, I found this PNP circuit but this circuit only turn on relay forawhile only.

So, my question is, how can I turn on dc pump by removing the motor shown in the picture and use the voltage at black/red wire to trigger a relay?

Something like this:

When voltage detected Turn ON relay. Stay relay turn ON until next detection (based on timer setting)

Voltage detect again then Turn OFF relay this time. Stay OFF until next trigger.


texts: Supply voltage in a current mirror necessary?

texts:
Consider the current mirror below (circuit taken from [Razavi]). I wonder about the \$ V_{DD} \$ in the circuit. No matter if its there or not, \$ V_{GS} \$ of M1 stays the same and therefore also \$ I_D \$ of M2, since the current charges up parasitic capacitances of M1 and causes a voltage across it. This I also verified by simulation, see the plot below (\net01 and \net02 are the \$ V_{GS} \$ of M1 with \$ V_{DD} \$ and without). Is there any reason why \$ V_{DD} \$ is connected there?

simulate this circuit – Schematic created using CircuitLab

EDIT:
I simulated the circuit until 100V, \$ V_{GS} \$ stays the same. Here is the circuit:


texts: I have a small SOT-26 (6 pins) device that is used in a MOSFET-based SMPS. It may be a PWM controller to switch the MOSFET. I need to identify it, but I can't find the component code anywhere at all. The code is 30653. Like in this image


texts: Calculating a good charge current for 3s156p 18650

texts:
I have built a 3s 156 p Samsung 22p pack to use as a house battery in my van. I'm trying to find a charger for it. Currently I am using my balance charger tenergy tb6b. Here is a screenshot with the data sheet on it. How would I use this information to calculate charge current and any recommendations on a charger. So I need to find an AC/DC charger for it when on shore power  and considering the  Genasun GV-10 for solar charging.

Thanks in advance!!!


texts: Modify LED strip from 4 AAA battery power to 12V DC

texts:
I wanted to put some light to my 3D printer. The power supply outputs 12V DC and I have this old car workshop LED torch that had it's batteries leaked. I disassembled it and cleaned the salt from the leak. I'd now want to remove the battery connectors and replace them with a cable that goes to a socket where I can plug in 12V DC from the power supply of the 3D printer.

The circuit board of the thing is quite simple. It's basically just the switch and a resistor between the (clean) battery connector and the red cable.

The LED strip has 10 white LEDs that I don't know the exact type, connected in parallel. I just know that they been running on 4x 1.5V AAA batteries (=6V).

Can I just run this on 12V or would I better replace the resistor so the LEDs don't heat up too much and lose life? Which size should the resistor be to run the strip from 12V DC?


texts: Allegro OrCAD Capture: Crashing after DRC check

texts:
Issue: The OrCAD Capture software by Cadence is continually crashing. The version I have is SPB_16.5.

Problem: I can run ONE DRC check fine, however; when I run another DRC on my schematic, the whole software crashes and I am no longer able to do any DRC checks on that project.

I even tested a completely working project from the past and ran a DRC check, it ran fine for FIRST DRC run but crashes on the second DRC run and never works again.

I have tried restarting the software, trying new projects, restarting the computer, and updating the cache on hierarchy.

It seems like there is an issue whenever I want to do more than one DRC check and something corrupts the project or something to do with the cache?

Any solutions to this issue?


texts:
is it possible that a RLC filter works as an amplifier? If it works at resonant frequency, then the output will be greater than the input.

Thank for your time.


texts:
http://www.electronicecircuits.com/electronic-circuits/cd4060-timer-circuit-1-minute-to-2-hours
I've replicated the circuit in the given link but \$D_2\$ in my circuit doesn't work at all. Also, the relay doesn't operate. I tried unplugging the relay.
LED \$D_1\$ is normally working and blinks with a time interval which I can change using \$VR_1\$.


texts:
I need a really small 2-pin connector, a cable connector on one side, and a surface-mount jack on the other.  These two items at AllElectronics are pretty close:

Small Battery Connector, 2mm spacing
Header for Small Battery Connector

What is the general name for these two items, so I can search Digikey or Molex?  And anyone know the exact part numbers of the above parts?  (AllElectronics doesn't know)

Update:

As per jluciani's awesome answer, these are definitely JST parts.  Mouser doesn't carry JST, but Digikey does as does AlliedElec.   And it looks like JST makes SMT variants of the PCB mount header as well as small pitch connectors too.


texts: Need help to explain the difference between S11 measurement and simulation of a coil antenna

texts: I am trying to characterize a small coil/spring antenna that works with a transceiver module at 433 MHz. The module size is ~15*30 mm which serves as the ground plane. The coil size is 5*20 mm, 20 turns. I use FEKO and SEMCAD for modeling and simulation, the magnitude of S11 at resonate frequency (560 MHz instead of 433 MHz) is around -2 dB (agreed in FEKO and SEMCAD). I did a measurement by soldering the coil to a piece of copper plated board with the same size as the transceiver module together with a SMA connector. The measured resonate frequency is 520 MHz(not the target one either) and the magnitude of S11 is around -15 dB. Could you please shed lights on the difference between measurement and simulation? Thanks!


texts: Why doesn't a Sallen-Key Butterworth Filter ring?

texts: I was under the impression that the differences between a Chebyshev, Butterworth, and Bessel filter was that they represented the cases of an underdamped, critically damped, and overdamped systems, respectively. However, after revisiting the transfer function for a second-order Sallen-Key filter, it seems I am mistaken as a Butterworth filter is defined with \$\mathrm{Q} = \frac{1}{\sqrt{2}}\$ or 0.707 placing it in the underdamped category. For a critically-damped filter, Q must be equal to 0.5. Why then doesn't an ideal Butterworth filter seem to exhibit ringing as can be seen with a Chebyshev filter?


texts: How do I charge a 6V, Lead Acid, 4.5 Ah battery using a 3W solar panel?

texts:
I have a solar panel with ratings: Vmp=8.8V and Imp=0.3A

Using this i have to charge a 6V Lead Acid battery whose capacity is 4500mAh.

I have searched the internet a lot and tried many circuits but haven't got any proper solution. Can you people help me out with this?


texts: Programming CC430F5137 using another microcontroller

texts: I have a CC430F5137 and the board schematic all ready for my application to that requires capturing data over bluetooth. I wish to program the CC430F5137 using another platform except the conventional programmer since I'm short of money for the project. Other platforms I have are: Tiva series Launchpad, Stellaris launchpad, MSP430 Launch pad, Arduino, Atmega 32 development board. Please help me by assisting in which to use and how.


texts: Mesh analysis - current source in one mesh?

texts:
Is it possible to use mesh analysis when there's a current source in one of the mesh? (i.e the current source is not between the two mesh to form a supermesh)

In the following circuit, I was able to get rid of the 8A and 2A sources by using source transformation to voltage sources. However, I am not sure what to do with the 4A current source in mesh 3?

What would be a good approach to this problem?

EDIT
i am looking for branch currents i1,i2,i3,i4.

EDIT2
After source transformation, this is what i get but I am still not able to deal with 4A current source.


texts: MCP23017 IO expander not properly pulling up signal

texts:
I'm writing firmware on a particle argon board that needs to use the MCP23017 IO expander to detect if two pins are grounded or not for a valve actuator.
The two pins are configured as
signals[SIGNAL_VLV_1_OPEN].ioExpander->pinMode(signals[SIGNAL_VLV_1_OPEN].ioExpanderPin, INPUT);
signals[SIGNAL_VLV_1_CLOSE].ioExpander->pinMode(signals[SIGNAL_VLV_1_CLOSE].ioExpanderPin, INPUT);
I have also pulled up both pins with the IO expander.
signals[SIGNAL_VLV_1_OPEN].ioExpander->pullUp(signals[SIGNAL_VLV_1_OPEN].ioExpanderPin, HIGH);
signals[SIGNAL_VLV_1_CLOSE].ioExpander->pullUp(signals[SIGNAL_VLV_1_CLOSE].ioExpanderPin, HIGH);
I have verified both pins were mapped correctly.
When the valve actuator fully closes it grounds SIGNAL_VLV_1_CLOSE, and un-grounds SIGNAL_VLV_1_OPEN, and vice versa when the valve actuator fully opens. However when I'm testing the device, after one command of open or close the IO expander no longer properly pulls up the signal instead the signal floats around 30mV to 200mV which is not enough for the particle board to recognize it as a digital high. I also have buttons on the command module that were configured in the same way as the pins shown above, but they don't experience the same issues. What could be the possible reasons causing the IO expander to not properly pull up the signal?


texts: Logic Level MOSFET IRLZ44N - under Wemos mini

texts:
I used IRLZ44N with Arduino Nano in order to dimm a 12v LED strip.

When tried to use it with Wemos Mini - I get only 7.6v max ( when controlling a 12v source ).

Probing the output pin (D3 ) - voltage is 3.3v, meaning it is at its max.

Is it due to different Logic Level ( 5v for Arduino ) ?

If so - is there a way to use this MOSFET for same application ?

** EDIT 1 ** Adding Schematic pic

Schematic is same, except:

1) Wemos Mini instead of Arduino

2) Load is LED strip , not a motor.


texts: Using a A22680 psu to power a 1000w induction coil

texts: Hoping for some help with my project im struggleing with my A22680 Psu the plan is to use it to power a 1000w induction coil for use in a waste oil heater to keep my workshop warm. I have shorted out the relevant pins to ground and have 48v on the contacts great I thought ,however when I connect my inductor to it the psu shuts off and the warning light is illuminated. Am I missing something? I hoped it was a simple thing to do but it's proving difficult. Thanks In advance


texts: Angel Eyes RGB LED Ring Light Wiring Extension

texts:
the cables aren't long enough and I want them to be black. Can anyone please tell me what this type of wire is called? It has four very small cores and runs on DC12V to supply power to four of these lights.
https://imgur.com/a/au98DS2
LED RGB 0.52mm Cable 4-Core? How about the connectors? Are they micro JST? I can't find connectors that will fit 0.52mm cable nor can I locate the crimps that must be added to the cable before inserting into the connectors.
The cables appear to be connected to the PCB using super glue (it's solid, unlike hot glue). I was hoping to attach new cables from the PCB but think I will have to attach to the existing cables.


texts: How does my breadboard circuit diagram look? Is my circuit going to explode?

texts:
I'm working on my first Arduino project and I thought I picked something simple enough. But before I set my breadboard on fire or ruin any of my components, I wanted to make sure my plan made since because I'm synthesizing several tutorials and data sources.
I am mostly confident I have selected the right components, but want to be sure I am connecting everything in the right order.
The goal of this project is to press a button which will activate an LED (internal to the button) and activate a solenoid valve. The button/LED and Arduino Uno board require 5V power and the solenoid valve requires 12V power.
Below is a diagram of my planned circuitry and here is a quick description of it:
Right Side of Breadboard (12V power circuit):

Power Arduino board with 12V power source
Pass 12V power to one row on the breadboard through the VIN pin
Pass power from the 12V row to a 12V solenoid valve
Connect the other solenoid wire to an empty row on the breadboard
Attach a diode from the row with the negative solenoid wire to the row with the row used to pass a 12V current through the positive solenoid wire to restrict the flow in that direction
Attach one ground pin on the Arduino board to another row on the breadboard
Attach a darlington transistor with the base pin connected to the ground row from the Arduino board
Connect the collector pin from the transistor to the row with the negative solenoid wire
Attach a 1K Ohm resistor to the emitter in of the transistor and attach the other end of the resistor to a new row
Finally, attach that row containing the other end of the resistor to a digital I/O pin on the Arduino

Left Side of Breadboard (5V power circuit):

Connect 5V pin on Arduino to new row on breadboard
Connect one positive wire to button switch contact and one to LED contact (integrated with button)
Connect another ground pin on Arduino to a new row on breadboard
Connect 10K Ohm resistor from ground row to new row on breadboard
From that row, connect one wire to the positive button switch contact and another wire to a new Arduino I/O pin
Connect 220 Ohm resistor from ground row to new row on breadboard
From that row, connect one wire to the positive LED contact and another wire to a new Arduino I/O pin

Some of the resources I referenced:

https://www.bc-robotics.com/tutorials/controlling-a-solenoid-valve-with-arduino/
https://core-electronics.com.au/tutorials/solenoid-control-with-arduino.html
https://www.arduino.cc/en/tutorial/button
https://www.instructables.com/id/Plug-and-Play-Arcade-Buttons/

Some of my components:

Arduino 12V Power Supply (https://thepihut.com/products/arduino-universal-power-supply-12v-2a-high-voltage)
12V Solenoid Valve (https://ussolid.com/u-s-solid-electric-solenoid-valve-1-4-12v-dc-solenoid-valve-brass-body-normally-closed-viton-seal.html)
Arcade Button (https://www.adafruit.com/product/3491)
Arduino Uno REV3
Tiny breadboard, breadboard wires, quick connect wires
1N4001 Rectifier Diode
TIP120 Power Darlington Transistor
Resistors of various values

EDIT 6-21-20
Below is my second attempt at a circuit schematic.

The first "half" of my project is complete, with the button and LEDs working as expected (obviously this part was easier). I don't have the 12V power supply yet so I can't test the other "half."

EDIT
I'd love to hear any feedback on my circuit schematic (first time making a diagram like this as well):


texts:
I have a main board with a 10/100 MAC and PHY.
This board also includes a discrete magnetics.
The board is connected via a suitable high speed board-to-board connector to another board, that contains the RJ-45 port. This port also contains magnetics.

Is there a problem with the signal being "magnetized" twice?
The RJ-45 port on the second board is preferred to be with magnetics, because it will be used with other projects that won't necessarily have a discrete magnetic element.

Thanks,
Gabriel


texts: How to differentiate between load and short circuit

texts:
I am working on a project. The goal is to differentiate between short circuit and load. I am trying to use differential amplifier. At load there are 2 to 3 millivolts. I need to compare them with zero volt and get a reasonable volt at output of this opamp.

How do I differentiate between a load and short circuit on the output of a differential amplifier?


texts:
Is there any standard or common numbering system for PCB layer numbers? I'm using Altium.
I imported a few different components from a couple of libraries and found that they put things like designators, 3d bodies etc. all over different layers.
I'd like to settle on a standard 'put designator on layer XX, put 3d body on layer YY, put board outline on layer ZZ' standard for my designs, so that I can export assembly guides and other manufacturing drawings easily.


texts: multiplexing control signal on speaker cable

texts:
I need to put an alarm siren close to the location of one of my audio speakers. But I don't have a dedicated cable towards this siren. Because the alarm control unit is close to my speaker amplifier I want to use the speaker cable for transmitting a trigger signal for the siren as well.

At the alarm-control-unit/amplifier side I can use an audio relay to connect the speaker cable either with the amplifier or with the siren signal based on whether the alarm is armed or not. (When armed, I don't need audio.)

But on the speaker/siren side I also need to drive a relay to switch between siren and speaker connection. I was thinking on using an Arduino to detect a DC signal on the speaker cable for this purpose, via one of its analog input pins.

Any suggestion for the electronics to use, in particular on the speaker/siren side? Or other cheap and simple mechanisms to multiplex the siren trigger signal on the audio signal?

My first thoughts:
Reduce the siren signal level via a voltage divider to a lower level that still can be detected by the Arduino but does not cause a "plop" on the speaker.
And a diode in series with a zener diode in order to clip the AC audio signal between 0 and 5V, before feeding it to an analog input pin of the Arduino?


texts: Will there be any effects on a signal in a long wire?

texts: I am going to need a large length of wire from my microcontroller analogue input to a LDR or similar sensor. The length of wire is likely to be about 100m so will it have any affects on the reading the ADC? Is there anyway I can reduce the effects?


texts: 1-wire interfacing with motor (design suggestion and review)

texts:
For my application, I need to deploy many sensors and a motor. So I chose the 1-wire bus protocol from Dallas/Maxim. Also, I am using temperature sensors which support one-wire protocol. So I thought to design a custom PCB - block diagram below.

But then I am not sure if it is a good option. I have a few questions:

Should I use this protocol even though it is slower than I2C?
Is it reliable?
How do I interface a normal device (motor) to the 1-wire bus? Are there any modules I can use for it?
Is it possible for any other protocol to be used, like CAN protocol?

Here is my design consideration.
It receives the duty cycle in percentage and the frequency and saves it until a new duty cycle input is given. A DAC converts this data to an analog value, supplies it to a PWM generator (duty cycle and frequency) and these signals are used to drive the motor.

I am seeking suggestions about this protocol, design and modules I could use.


texts:
How is it that slotless stators yield torque, on par with slotted stators, with less amount of copper windings, and no teeth to concentrate the flux towards the permanent magnets, and be efficient too. I understand the air gap losses are minimised by the use of rare earth magnets(NdFeB), and increase in rotor diameter maybe compensates for the less number of turns per coil. But even so, how could the absence of teeth be compensated with.

The stator still has laminated backing for the windings. How important is their role. Sorry if i am deviating.

source: http://www.techbriefs.com/component/content/article/moco/features/22932


texts: using mesh analysis with capacitors and impedances

texts:
My circuit analysis skills are a bit rusty; since, I been coding for a long time now. I'm analyzing a switching circuit's on and off cycle. I am solving for Vc2 in terms of D and ( 1 - D).

here is the circuit below :

On D, the SW2 and SW3 conduct. so, I made the following simplified circuit

Would the easiest approach be to use mesh analysis and treat the cap / inductance as impedance?


texts:
I am going to route Ethernet differential par in a four layer PCB which contains Top, PWR planes, GND plane and Bottom stackup. These diff pair are going to be routed in the top layer.
In order to maintain the impedance, I would like to use a power plane as reference beneath the signals, instead of the GND plane, as it provides better dimensions for routing (width and spacing) in the PCB toolkit calculator. But I am afraid that, even an continuous power plane will not provide a proper reference for those Eth differential pairs.
This is because, the supply voltages of the Ethernet Phy is not the same as the board I am designing, they are two different PCBs. But they share the GND net
So my question is: is there any chance that a 3v3/1v8/5v power plane could provide a valid reference for those Ethernet MDI signals?