texts: STM32F3Discovery & LSM303DLHC magnetic field data not updating

texts:
I'm having trouble reading the 6 magnetic field data registers from the LSM303DLHC on my STM32F3Discovery board. (OUT_X_H_M, OUT_X_L_M, etc)

I used the STM32F3Discovery demo as an example for how to read from the compass sensor. I copied the Demo_CompassConfig() and Demo_CompassReadMag() functions provided in main.c of the demo. I also setup a virtual com port so I could dump text data to a terminal program on my PC and see the values I was reading.

I can read the acceleration data from same sensor just fine, but not the magnetic field data.

Like the code in the demo, I'm initializing the sensor like this:

LSM303DLHCMag_InitTypeDef LSM303DLHC_InitStructure;
LSM303DLHC_InitStructure.Temperature_Sensor = LSM303DLHC_TEMPSENSOR_DISABLE;
LSM303DLHC_InitStructure.MagOutput_DataRate = LSM303DLHC_ODR_7_5_HZ ;
LSM303DLHC_InitStructure.MagFull_Scale = LSM303DLHC_FS_8_1_GA;
LSM303DLHC_InitStructure.Working_Mode = LSM303DLHC_CONTINUOS_CONVERSION;
LSM303DLHC_MagInit(&LSM303DLHC_InitStructure);

When I try to read the X Y Z values of the magnetic field data using the demo's read function, they show the first reading measured, but then never update and always stay the same.

uint8_t buffer[3];
while (1) {
   // ...
   Demo_CompassReadMag(buffer);
   // ...
}

If I call LSM303DLHC_MagGetDataStatus() before and after the read, it's always 0x03. Bit 0 indicates a new set of measurements is available, and Bit 1 indicates that the output registers are locked.

In my searching I read that the 6 output registers are locked until they are all read, and then the next measured data is loaded for another read. The data seems to be correct if I power cycle the device in different orientations and read it, but it seems to be locking the first value and then never loading any more. So I tried reading all 6 values at once to unlock the output registers.

uint8_t buffer[6];
while (1) {
   // ...
   LSM303DLHC_Read(MAG_I2C_ADDRESS, LSM303DLHC_OUT_X_H_M, buffer, 6);
   // ...
}

Same thing, the XYZ data never changes. I even tried reading all 13 bytes (0x00 to 0x0C) from the magnetic sensor. Still does not update.

If I reconfigure the device after every read, I can get real time data out of the sensor. Obviously this is not what you're supposed to do.

uint8_t buffer[3];
while (1) {
   // ...
   Demo_CompassReadMag(buffer);
   Demo_CompassConfig();
   // ...
}

I'm guessing that I'm doing something wrong or missing something simple, and the lock is never being released, and the next set of values is never being loaded.

Can anyone tell me how you are supposed to read the 6 magnetic field data values out and reset the output register lock? I've tried a lot of things and can't get it working.


texts: In the figure shown below, why the current through 10 ohm resistor is zero?

texts:
This is a practice question from the book circuit theory by A. Chakrabarti. I didn't understand how  current through the branch C-D is zero.

Why is the current not zero?


texts:
The actual question is, "Develope the AC-equivalent circuit (Using Hybrid-Pi model for transistor), from which you can calculate the voltage gain, and the input and the output impedances"

We haven't been taught anything about Hybrid-Pi model yet, i tried going through my textbook and some youtube tutorial, but it was too broad before i could actually solve this circuit. I set capacitors to short circuit, and Vcc to 0v/ground. But the main problem is (transistor).

It would be really helpful, if i could get an explanation (with figure) about the Hybrid-Pi model of circuit above.


texts: Using my DMM and the diode selector, the SMDs 3528 in a brand new Led bulb does not light. I used this method to test the classic "round" leds but in this case it does not work. What seems to be wrong here?


texts:
For one camera, the black level of the sensor will make the output non-zero when it is covered. For example the output of the sensor is 10bit and black level is 63, if the output is reduced by black level, the range of the output will be 0~960. So the dynamic range is reduced from 0~1023 t0 0~960. Am I right?

From one document, there is one figure enter image description here

I am not a electronic engineer, so I don't understand why the analog offset is added to pixel voltage. The output of ADC is reduced by digital offset, do this will reduce dynamic range greatly?


texts: How would the total charge density of n type semiconductor formula change after applying bias?

texts:
The following formula is the total charge density of n type semiconductor. When we applied, lets say, 2 V bias to this semiconductor, how would this formula change?

(Nc: effective density of states in conduction band; Nd: n-type donor concentration; Ec: bottom of the conduction band energy; Ef: Fermi energy level; Ed: Donor ionization energy; k: Boltzmann constant; T: temperature)


texts: Choose proper grounding when using multiple LDO, buck, buck-boost and invering regulators

texts:
I'm a little stumped by how to avoid ground loops. I need to connect to a mostly analog external component that requires VCC_12V, VCC_5V, VCC_3V3, VCC_N7V (\$-7.0V\$) and GND. I assume the external component returns all supplies back to GND.

However, in order to supply these voltages, I have designed regulators providing quiet analog voltages using LDOs following buck, buck-boost and inverting switching regulators. Due to the different voltages, the ground outputs are necessarily different for each of the voltages.

Below, I've indicated why there would be a loop, if I connect the returns of the supplies.

simulate this circuit – Schematic created using CircuitLab

The sensible thing would be to connect the external components ground to the ground of my power source (as indicated), but I fear that there will be too much noise, since now the noisy traces are included in the voltage levels.


texts: How to find the equivalent resistance for YY parallel connection

texts:
I am trying to find how to break apart a Y-Y connection to find the equivalent resistance. I understand how to find the equivalent resistance for 2 Y circuits in series, but not parallel.  I understand how to transform from delta to Y and back, but am unable to find a simplified circuit for this design:

o--------o--------------------o
|         \        o        /
|          \      /\       /
|           R1   /  \     R6
|            \  R3   R4  /
|             \ /     \ /
|              o       o
PS             |       |
|              R2      R5
|              |       |
o--------------o-------o

Where "PS" is the power source and "o" is the nodes and "Rx" is the different resistors.
Please Help.


texts:
Hi, part of my project requires me to amplify an audio signal coming from an electret condenser microphone which outputs an average of 10mVpp to approximately 2.5Vpp. I Used two cascaded non-inverting TL071 OP-amps since one Op-amp doesn't have enough GBW. The output of the mic is low-pass filtered with a cut-off frequency of around 13kHz.

It works perfectly if I input a signal from the signal generator, the output is as required, however with the signal from the microphone there is no output, just a DC offset which is coupled by the capacitor at the end. I also tried buffering the output form the mic.
Any help would be much appreciated.

EDIT:
Didn't realize the error in the schematic, resistor 1k should be between mic and 5V.


texts: Microchip MCHV reference design Ic Ia IBus current waveforms

texts:
I have built a Microchip MCHV board (ACIM Inverter based driver) from the schematics on the MCHV user manual. http://ww1.microchip.com/downloads/en/DeviceDoc/dsPICDEM%20MCHV%20development%20board%20User%20Guide.pdf) I can run a motor in open loop using AN1206 demo code. I cannot get the closed loop algorithm to work. It depends on analogue signals Ia and Ib.

Attached are DMCI plots of the Ibus Ia Ib and zero crossing signals for a running average of 8 measurements and a plot of the same signals without applying a running average. Also attached are the voltage plots, running a motor with no load.

I don't think they are correct. Does anyone have sample waveforms from an actual MCHV board they can share so I can compare mine or perhaps by looking at my waveforms can comment on what may be wrong.

The peaks seem very small, and seem to be swamped by noise, I have star grounded the DC bus -, agnd and dgnd and have been very careful to separate my ground planes. Does anyone have an idea as to where the noise may be coming from?
I have invested a ton of time into this and really need some help figuring out the problem.

Thanks


texts: What is this "flip-flop-like" circuit element from the Apollo Guidance Computer?

texts:
I've been trying to condense the pure NOR-gate based Apollo Guidance Computer schematics into a more higher level view of the logic elements and came across this interesting piece:

simulate this circuit – Schematic created using CircuitLab
From this page in the AGC archives.
At first glance, it just looks like a flip flop based on the crossing feedback, but the top NOR gate has 3 inputs, not 2, so it's not a standard flip flop built from 2 input NOR gates.
So then, what exactly is it doing? I'm guessing it's still a flip flop of some sort since it's clearly storing a bit, but what is the extra input on the top NOR-gate for?


texts: Using an SSR photoelectric sensor with Arduino

texts:
I'm wondering if I can use this photoelectric sensor with an Arduino. I don't have much experience with these sensors or with relays, and I'm sometimes confused by output switch ratings, so I can use the help.

Here's my understanding. Two of the sensor's cables are for power supply. The other two are listed as "isolated AC/DC outputs" and I want to connect those to an Arduino to detect the sensor's state change. The data sheet says "Output Load:  300mA @ 240 VAC/VDC." I think that means the maximum rating. My question is, if an Arduino only sources 40mA at 5V, do I need to figure out if there is a minimum requirement for sensor's outputs? And if so, how do I do that?


texts:
I need to multiply 2 3bit numbers. I tried that:

but it does not seem to work.

In this example, the output should be 49. so that is that 77?


texts: How do you maintain a constant power supply to a place 24/7 using a generator, commercial power, or solar?

texts: Hi, I'm Sadiq. I'm doing bachelor of science in telecommunication engineering. I was given the above mentioned question which was part of an academic research project, but unfortunately I was not able to get an answer for it, so I forwarded it.


texts: UART signals connected to RJ45 connector?

texts:
I'm looking at a schematics and found something strange to me.
The schematics connects UART TX/RX signals to a RJ45 connector (leave other unused pins unconnected).
Does anyone know such application?
What's the purpose of such design?
Thanks.

David

I can't get the exactly schematics, just a block diagram like this:


texts:
I'm building an assembly that will drive some infrared LEDs.  Although the final product will use three, I'm just playing with one for testing purposes at the moment.

The spec sheet for the LEDs I'm using can be found at http://www.osram-os.com/Graphics/XPic0/00083225_0.pdf

If I'm reading that sheet correctly, the maximum current for this LED is 100mA.  The information I have found online suggests that you shouldn't run them at their maximum output except in short bursts so I was going to go with 50mA.

I used the calculator at http://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-led-series-resistor?WT.srch=1&WT.medium=cpc&WT.mc_id=IQ63967658-VQ2-g-VQ6-36682054515-VQ15-1t1-VQ16-c

I'm using a battery case that holds 2AA's so I entered 3 as my supply voltage, forward voltage of 1.5 (from the spec sheet), and 50mA as the forward current.  According to the calculator I should be using a 30Ohm, which is what I have.

I pointed the camera on my cell phone at our TV remote and verified that it does indeed "see" IR, but when I test my circuit I get nothing.  I suspect I'm interpreting something on the spec sheet wrong and sized the resistor incorrectly.  Can someone set me straight?

Here is some additional information per your requests.  First, a pic (albeit fuzzy) of the circuit...

Since it is a little fuzzy, here's a quick tour.  Battery to power rails.  Resistor from negative power rail to A9.  Negative leg of the LED (verified per spec sheet) in E9, positive leg in F9.  Jumper from H9 to positive rail.  I put some wires on the power rails on row 15 to make it easier to measure voltage across the battery.

When I measure across the battery I get 3.153v, across the resistor is 2.073, and across the LED is 1.077.  Everything is around the values I expected, I'm beginning to wonder if my assumption that my cell phone should be able to see the light is flawed.  It does see activity from multiple remote controls I have here so I would have thought it would see this as well.  Going to pick up a red LED today for testing purposes but if this new information causes any light bulbs to go on for any of you (no pun intended) I'm always happy to hear anything you have to share.  This is a learning experience for me, many thanks to the community.


texts:
I want to apply a time delay to a signal which is created from a pulse generator.

Pulse generator : T = 4e-05.
I am using a powergui with discrete time and Sample time: 4e-07.

In order to succeed this i used the "Discrete variable time delay" block  with sample time 4e-07 and the result is :

The first one is the original signal and the second one is the signal with the delay.
As you can see there is problem in the seconde signal.
One way to sovle this problem is to increase the Sample time but this with make my simulation very slow.

Do you have any suggestions ?

P.S. The delay time is an external signal with a variable value so I can not use the delay at the Pulse generator .

Thanks in advance.


texts: Having trouble deducing bandwidth for which differentiation occurs with op amp

texts:
So I had to construct this (practical differentiation) and deduce the bandwidth for which the differentiation occurs. We also had to deduce for what higher frequencies it turns into an inverting amplifier. I am very confused by what I am looking at because it doesnt look correct. The top is not anywhere near flat enough. However, I was playing around with it, and changing the capacitor to 100uF corrected this. The OP amp in question is LM324, with a unity gain of 1Mhz.

This is the frequency response of the circuit. The amplification is in DB. Am I correct in thinking that the differentiation occurs from 112.179 hz to 27.295k Hz? And that the max amplification is at 1.7507k Hz. Lastly, that the bandwidth is  27.295k - 112.179 = 27182.821 hz? It turns into an inverting amplifier at frequencies greater than 27.295k.

and without R3 ...


texts: Is there some kind of standard of modbus input register?

texts:
As the title said,
based on your experience, is there a such thing?
If no, which are the most commonly used?
for example in a sensor, the input registers as follows:

| Starting Address | Info        |
|------------------|-------------|
| 0x0              | Level       |
| 0x2              | Temperature |
| 0x26             | Total Flux  |

which is most common between manufacturers? any articles or a list about it?


texts: Whats the overrall power available from two PSUs in series?

texts:
Consider this circuit:

PSU 1 is rated at 100w, PSU 2 is rated at 200w.

How do I calculate how much power is available to the load, given the mis-matched power supplies?


texts: Driving transistor with the output of CMOS inverter

texts:
This is kind of a follow-up question to my last question (CMOS inverter configuration). I have succesfully used an Arduino digital output pin. The output pin drives IN1 and IN3 inputs of an L298N engine driver (with max 100 microA input current), as well as a CD4049 hex inverter input. The hex inverter output drives the other 2 inputs of the driver (IN2, IN4). This has worked without a problem. When I try to drive another load from the inverted output is when I get a problem.

simulate this circuit – Schematic created using CircuitLab

I tried to drive at the same time the 2 inputs (IN2 and IN4) of the L298N and the base of a NPN BJT transistor 2N2222. When the inverter input was high everything worked well, and when the inverter input was low, neither the L298N driver worked or the 2 LED's through the transistor. I then though that maybe the base current was too high, so I thought I would switch with an N-channel MOSFET BS170. I replaced it Gate-Base, Drain-Collector and Source-Emitter. If the input went low, the output would go high on the CD4049. But when the input went high again, the output stayed high as well.

What am I doing wrong here?
How do I correctly drive a NPN BJT or N-channel MOSFET from the output of a CMOS inverter like the CD4049?


texts: Middle-Tapped Transformer Full-Wave Rectifier Vs. Full-Wave Bridge Rectifier

texts:
In terms of output voltage, which one of these would be best?  Coming into this, I would have to say the center-tapped transformer full-wave rectifier would allow the most accurate output voltage (only 1 diode voltage drop).

I've always heard: Cost of the middle-tapped transformer is greater than 2 more diodes.  Is this all that it comes down to?


texts: UDP streaming over WiFi problem when operating outdoor at ground level

texts:
I am working with the following setup: I have an SBC running Ubuntu 18. The board is installed on an outdoor device. The board generates a wireless hotspot and runs a python script which streams UDP packets to the mobile devices that are connected to the hotspot, using the socket module. An Android app receives the packets and displays the contents.
Now, when I test the system indoors, everything works fine. The packets are correctly received and processed. However, when I test it outdoors, with the device operating at about 20cm from the ground, I have many timeout exceptions waiting for the UDP packets. The problem disappears if I lift the device from the ground. In any case, the WiFi signal is strong (I get the same problem even when the mobile device is very close to the board).
How can I diagnose the problem? Is there a way to fix it?


texts: Is there a mathematical proof that reactive power regulates voltage?

texts:
So after studying the power triangle and trying to conceptualize real power and reactive power, I seem to have come across a contradiction, at least in my own head. Most explanations disregard reactive power as "useless" power or power that we don't want to pay for. But then i came across the fact that reactive power is needed to control voltage. "In general terms, decreasing reactive power causes voltage to fall while increasing it causes voltage to rise." Well, aside from just believing it, i would like to see some type of mathematical proof that shows it? I know the equation for reactive power (Q)=VIsin(theta), but i don't see the relationship that shows reactive power helps control voltage.

Quote is taken from: https://electrical-engineering-portal.com/how-reactive-power-is-helpful-to-maintain-a-system-healthy


texts: Stopping flyback spark from inductor, but only some of the time

texts:
I'm currently working on a project designing an experimental engine control unit, which ignites a flammable mixture with a standard spark plug and standard ignition coil (the old style https://en.wikipedia.org/wiki/Ignition_coil). The primary is first charged to a nominal voltage (12V I think) then, to generate the spark, the primary voltage is quickly dropped to zero and the collapsing magnetic field in the secondary inductor causes a voltage spike across the spark plug. I'm controlling the primary voltage with a microprocessor and MOSFET and charge the primary when the engine is "armed" and turn off the coil when "arm" is switched off.
I'd like a way of making the spark coil fail-safe, i.e. if there is a sudden power cut, no spark will be created due to the sudden voltage drop, but be able to generate a spark by intentionally dropping the voltage whenever needed. This needs to be 100% reliable, as it could be safety-critical if there is a build up of explosive gasses and an emergency shutdown is needed. I understand usually you'd connect a flyback diode (plus Zener/resistor) in reverse bias across the coil to stop the voltage spike, but the voltage spike is needed to generate a spark...
I looked at make-before-break relays to connect the flyback diode before the primary current is switched off, but couldn't really find any available and I'm not sure how they could be connected to stop the spark in the event of a power cut or when the "arm" switch is turned off. Likewise with using solid-state switches to include a diode in the loop, I'm not sure if it could be connected quickly enough to beat the voltage spike.
Thanks in advance for any input, this has been puzzling me for months now. I'm a mechanical engineer at heart, so please be patient if I've misunderstood anything in the above!


texts:
I am working on the following system. The RPi will turn off at a low battery signal emitted by the uC (through a GPIO pin), and after a few seconds, I need to be able to turn it off completely (cutting 5V) and then be able to turn it on again. I have thought of a mosfet, controlled from the uC (3.3 logic level) but I don't know which one I can choose and how can i connect it.
any ideas?


texts: What are some good circuits for learning about capacitors?

texts: I'm looking to gain an in depth understanding of capacitors (timing constants, filtering, etc..) What are some good circuits to learn about capacitors? I've got all the equipment I think I need (oscilloscope, waveform generator, DMM, breadboards, etc)


texts: Is it possible to design a SD 3.0 controller in UHS-ii/uhs-i mode using simplified specifications?

texts:
I've been for while looking at how to store sampled data up to a rate of 30MBytes/s; an SD 3.0 host controller core in uhs-ii/uhs-i mode fits the requirements.
I'm not planning to buy the SD full spec and I think it's quite possible to make an SD 2.0 host controller core using just the simplified spec, but is it possible to make an SD 3 host controller in UHS-ii mode too? (SD Assoc offers uhs-ii simplified addendum, but is it enough?). Maybe it doesn't include some crucial details that would lead me to a dead end.


texts: How to hack a body scale to be used as digital weight measure

texts:
I am looking for help with hacking a typical digital (body) weighing scale to use in a custom application. Is there some internal digital or analog output in body scales to directly get the measured values? How might I go about reading this output?

I thought about connecting the scale with an Arduino, Tinkerbot or Raspberry Pi for further processing, for instance to weigh other stuff and for home automation. I am not looking to build my own body scale from scratch, just adapt one to be able to extract the measured values. Body fat or similar nonsense (which cannot be measured reliably anyway) is not required.


texts:
I have a bi-directional current sense opamp (INA214), where I'd like to alternate the VREF between GND and 10V. Page 22 ("9.2.2 Bidirectional Operation") in the datasheet has more information.

I also have a TL431 which I'd like to use to provide a stable 10V reference.

What would be the best way to make a circuit, that receives a 0V/5V signal, to provide a reference voltage that is stable enough to act as a voltage reference? Ideally the circuit would have low power consumption when the output reference is GND.

Option 1: NPN on opamp signal

Maybe something like this? I'm not sure about the highest value possible for R1 (to reduce power consumption), and the other resistors as well.

simulate this circuit – Schematic created using CircuitLab

Option 2: Multiplexer

Perhaps using a CD4052B multiplexer?


texts: 33V residual AC voltage in domestic circuit when switched off? Neutral switching?

texts:
I have searched Google, but get bombarded with "RCD" type answers. I read a few answers here that may have been relevant but turned out not to be, so I post my question. Being my first, I may unintentionally break some rules - hopefully not.

I was about to make a change to a domestic light circuit so tested the light socket to ensure the circuit was dead and I had pulled the correct fuse. (Yes this circuit is 50-60 years old, hence no CB!)  What I discovered with the digital multimeter (set to 700V AC, as nearest higher setting) was that 33 AC volts existed whichever direction I connected the leads. And this is with the correct fuse removed!

Wanting to be more certain I used a light bulb to verify more digitally - i.e. 0 or 1.

I proceeded with the task which used the existing light wires as pull leads to get another cable down the wall. All finished I was set to reconnect the circuit exactly as before.

My understanding was that the Live wire went to the Common connection on the switch, so I reconnected the fuse and tested for the live wire with a neon single-connecton screwdriver and connected the one that 'glowed' to the Common terminal of the switch and the other to terminal 1.

At some point; either reconnection of the fuse or flipping the switch, the fuse blew. I have not replaced it, until I get to the bottom of this problem. So my questions are;

1 - first, does the live wire go to the common terminal on a two-way switch? (being used as 1-way currently, but hopefully soon to be two way).

2 - Has the neon screwdriver led me astray for which was the live wire?

3 - Is it possible that my house has neutral switching and if so, how do I find out? It has been illegal here in NZ for at least 60 years I would have thought. If neutral switching should I put the other wire to Common and the live one to terminal 1?

4 - Is 33 volts AC a concern when the circuit is off? I did not get any form of tingle when man-handling the wires. We have 240 V AC circuits in NZ for domestic wiring.

Thank you for any answers that you care to provide.


texts: Using a 3 input AND Gate as a 2 input one

texts: Two inputs are connected already. How should you connect the third input so that you can use a 3 input AND gate as a 2 input one.


texts:
I'm currently working on the development of some measurement equipment. For conversions I use a small ARM which runs on 3V3 and to display the results I use a graphical display running on 5V. This means that I have to shift the voltage levels from 3V3 to 5V and vice versa.

I have done some research on the topic and found out that there are numerous circuits on stackexchange alone (let go on the whole internet) to do it but I'm interested in how professional developers do it and how to achieve fast switching speeds for fast interfaces.

There is always the option to use a level shifter IC1 but those are expensive and most companies may want to avoid additional component cost. People have done it bidirectional with just a 2N7002 and two resistors[2] whereas other people did it with a transistor and two resistors configured as an inverter.

How do professional developers shift the voltage level from 3V3 to 5V logic and vice versa? I have never seen level converters in a professional product (except for chargepumps for RS232 and such) - Do they just connect 3V3 and 5V logic?

1For example the SN74AVCB164245VR from TI

[2]


texts:
If you look at the diagram there is only a + after the R1 resistor.
Not a + after the R2 resistor. But I was wondering why is there an arrow to the right after the R2 resistor. If I connect a led as in the diagram (the red color), then that light does nothing. Only if I break the connection from after R2 to Vin then the 2nd led works.

Can someone explain what is going on?

In case it matters, I have 2 10K pot meters and a 9volt battery.


texts: When should I change a logic level and how long should I hold it?

texts:
I'll start out by saying I'm a total newbie to this stuff, so I apologize if this is a silly question. For context, I'm trying to bit-bang the Low Pin Count bus using a FT232H.

Here's a timing diagram from the LPC specification:

Here's a logic analyzer capture of the LPC bus:

If I'm reading it correctly, the spec diagram shows LFRAME# and LAD[3:0] being set between the rising and falling edges of the previous clock and then sampled on the next rising edge. The LA capture, however, shows the signals changing only right at the rising clock edges. I assume that, realistically, sampling occurs shortly after the edge instead of right on it, correct?

The vultureprog programmer changes LCLK, LFRAME#, and LAD[3:0] in steps, so its waveform ends up like this:

(Transcribed from the code, as I don't have a board to test it on.)

Its similar to the spec diagram, but the signals change just before the rising clock edge instead of the previous falling one.

With the FT232H in MPSSE mode, I can produce a waveform like the one in the LA capture (that is, the signals change at the rising edge and hold until the next rising edge). When I run that through Sigrok's LPC protocol decoder, it doesn't sample the expected values for the Start or CT/DIR fields and the rest of the cycle is thrown off. Looking at the decoder's code, though, there are some issues like the TAR field being out of order for write cycles. It seems the original author didn't test it very extensively.

So is the protocol decoder wrong or am I misunderstanding how digital logic works and not changing my signals at the right time?


texts: Can someone identify these cable connectors?

texts:
The cable that i have attached in the pictures below need to be replaced. I don't know the names(types) of the two connectors so i need your help.

The device i need to connect:


texts:
Supposed you are using an Isolation Transformer with 115kV primary, should you worry about the capacitive current going through it? What would happen if you touch one of the output leads? Remember an isolation transformer secondary is independent from ground.

I always used isolation transformer when diagnosting circuits so I'd not get a shock or the equipment broken by having the path to ground.

To get better understanding. I'd like to know what would happen if the ground rods in North American utility pole were say stolen and at the same time your service panel ground rods didn't work because say the contacts got molds or disconnected and contact to ground completely lost . This would make the utility tansformer secondary floating, so your appliances enclosure could become live. What would happen if you touch the appliances metal enclosure like metallic washing machine body, would you get a shock? or be electrocuted theoretically? But how can you get shock when you were isolated from ground already.


texts: Current passing through zener diode at base of NPN

texts:
I want to find current through Zener diode. correct answer is 10.3 mA.

I tried to solve it this way.

i found Ib( base current)
Ib = Vcc-Vbe-Vz/10 so 20-10-0.7/10 = 0.93 mA.
My answer is wrong. Can you correct me?


texts: Does a USB PD source supply any voltage to a non USB PD compliant USB C device? If yes, how much?

texts:
I have a 40W USB PD compliant charger from my ultrabook. I recently bought a pair of headphones (Sony WH-1000XM4) which can be charged using a USB C Plug. Sadly I can not find in the specifications of these headphones whether they support the USB PD standard. It only says they are supposed to operate at 5V and draw 1.5A, so they are potentially not compatible.
So I'm wondering, what happens when a non USB PD compliant device is charged with a USB PD source? The source can supply 5-20V. I assume the device would be fried if it were to be exposed to the full 20V, but I wonder whether the source recognize that the device is not USB PD compatible and doesn't supply any voltage at all. This would make sense to me, as it seems like USB PD compliant devices "tell" the source which voltage they want.


texts:
I was wondering if anyone can help me understand how this circuit works.

I understand covering the photo conductors increases it's resistance but I'm not sure how the transistors come into play. This is a bidirectional motor and it is activated when I cover one of the photo conductors

Thanks in advance!


texts: Does resistor placement change power dissipation in simple LED circuit?

texts:
Does the power dissipation in an LED and resistor change depending on the resistor placement?

Let's assume the following:

Supply Voltage: 3.3v (DC)
LED Forward Voltage: 2.1v
Resistor: 330 Ohm

I think my problem is that I'm thinking that the circuit "starts" at 3.3v, then goes through the resistor which restricts current and then goes through the LED which drops voltage.  Alternatively, if I place the LED before the resistor, then the LED will drop the voltage (3.3v - 2.1v = 1.2v) before it reaches the resistor so the resistor is dissipating less heat?


texts: Phase shift near saturation mitigation in input stage amplifier -- How does this work, why does this work?

texts:
I'm trying to understand how this circuit works on the input stage to the 4192A Impedance Analyzer.

Apologies for the quality... this is the best scan I could find. The design is furnished with the following explanation:

  In parallel with the basic feedback loop (R145) for the current to voltage
  function, the secondary loop, consisting of R132, C112, and the class C
  bias push-pull amplifier stage (Q30 and Q31) applies a non-linear feedback
  to suppress the output for excessive inputs. Normally, both Q30 and Q31
  are off with no base bias. Over almost the entire voltage range of the
  amplifier output, the secondary feedback loop is open, so the I-V converter
  amplifier has a linear gain characteristic. When a transient unbalance input
  approaches the saturation level of the amplifier, Q30 and Q31 turn on
  in the peak region of the output before saturation occurs. As the secondary
  feedback loop decreases the gain of the I-V converter, further increase
  in the output voltage is suppressed. It moderates the saturation of the
  amplifier and, consequently, prevents a phase shift at the output (an
  effect of saturation). [From the 4192A service manual]

First of all, I want to ask if, after eliminating Q30 and Q31, there's a way to see how the described phase shift comes about near saturation. Is this a property of op-amps in general or just the way this amplifier is designed? This circuit is a kind of high gain amplifier with feedback and acts like an op-amp, right? Finally, I don't understand how adding Q30 and Q31 would cause the output to clip in a way that has less of a phase shift than driving the amplifier into saturation without Q30 and Q31 would. The only kind of phase shifting nonlinearity I understand is slew-induced distortion. Is that what they're referring to? I guess I can understand how using feedback to reduce the gain would reduce the slew rate, but the slewing is fastest near zero volts, which is where Q30 and Q31 are not reducing the gain. I had thought maybe the answer is in the time constant from R132 and C112, but this is only 316 ohms * 4.7 pF = 1.5 ns

Thanks in advance for having a look!

EDIT: Another thought. Could the phase shift be contributed by the amplifier's recovery time once driven into saturation? As in... if some of the BJTs are driven into saturation, I suppose you have to wait to remove the stored charge from the base before they come out of saturation and the amplifier responds. When the description says "saturation," do they perhaps not just mean "not railed," but also "no transistors are driven out of the active regime"


texts: Multiple resistors in series instead of using a single resistor has any advantage: heat produced by the resistors of diffent watts are different?

texts:
I have two doubts, requesting you to answer my doubts separately. :)

1) I need a resistance of 'X', so is it better to use a single resistor of 'X' value or multiple resistance of r1+r2+r3='X'?
What  I mean is using multiple resistors in series instead of using a single resistor has any advantage? Will it reduce the resistors getting overheated?

2) Consider a 1W 2k2 resistor and a 1/4W 2k2 resistor. Is the heat produced by resistors of different watts different? Which resistor will get more heated in the same conditions (I mean the current, voltage etc given both resistors are same)

Regards,
Kiran.


texts: Control 9.6v battery line (on/off) with a 5v I/O pin?

texts: I would like to control a DC 9.6v battery line (on/off) with a 5v digital I/O pin on a little microcontroller. I think the best way to do it is using a small relay (something like this), but I'm not sure so I'm here seeking the counsel of 9000's help.


texts:
I am trying to understand how to connect an ESP32's UART pins to my raspberry pi 3B+'s I2C pins.  I see several bridge chips available for this like TI's MSP430 Datasheet. But I am not very circuit savvy so I am having a difficult time.  The pins I need to use on the ESP32 are: GPIO 9 and 10, RX and TX respectively (UART1).  On the Raspberry Pi: GPIO 2 and 3, SDA and SCL respectively.  Does anyone know answers to the questions below?

Besides connecting the RPi, ESP, Vcc, GND pins to the bridge at the correct I/O positions on the chip, what additional circuitry would be needed to make good communication?

What the ESP32 code would look like (Arduino IDE)?

What the Pi's code would look like (python)?


texts: Can I develop constant force (pressure) from piezoelectric crystal?

texts: Can I develop constant force (pressure) from piezoelectric crystal applying constant voltage?


texts:
I got to understand what a LUT actually is. The inputs of a logic function acts as drivers for address lines of a memory block (typically a RAM block) and the address lines are decoded to point to a value which is passed on to the output.

Y=A^B

We store the values[0:3]=(0,1,1,0); And based on the input which acts as address,the corresponding output is enabled.

But how is this value actually stored?

I write y<=a xor b;

How is this put into the look up table? And how is this linked with the multiplexers and D-Flipflops?


texts:
I have a level shifter that uses a transistor to control the gate of a high voltage P-channel MOSFET, like this:

simulate this circuit – Schematic created using CircuitLab

This is designed to work at a nominal 100V HV supply, and works okay between 50 and 150V or so.  The input is logic level.  It works fine, except the switching time is a few microseconds.

I'd like to speed up the switching time to tens of nanoseconds if possible.

The things that make a bit tough are that the circuit is power constrained (drawing 1mA from HV through the level shifter while it's on is already kinda a lot), and also cost and space constrained (the circuit shown here fits in 15mm^2 and each component is under $0.01).  I probably can't use a gate driver IC, optoisolator, or isolated gate power supply or anything along those lines.  I could for example add a second BJT, some dioides or a few passives.

Is there a simple topology for speeding up switching in this type of circuit without increasing the constant power draw?


texts: Clarification on what the max freq of PIC24FJ64 is?

texts:
I'm confusing myself a bit here. The following is taken from this datasheet:

High-Performance CPU:

Modified Harvard Architecture
Up to 16 MIPS Operation @ 32 MHz

Now I want 16 MIPS, which is its max speed. But that 32Mhz, is that the xtal freq or the internal clock freq?

I currently have an 8Mhz xtal selected, and by using the PLL X4, that should give me the 32Mhz, but I'm not sure if the FOSC/2 happens before or after.

What xtal would I need to get max speed out of this device ?

Edit: I believe my current configuration is correct. That an 8Mhz xtal with PLL x4 enabled will give me the 16MIPs i require and that the divide by 2 for the internal clock cycle happens after the PLL.


texts:
I'm trying to choose the right size of smd mlcc ceramic capacitor.

Two of the biggest values of my capacitors are, 4.7uF and 10uF which I first chose to be 0603 because my pcb space is very limited.

Those capacitors are output capacitor in power manager IC (battery charger with power path), and decoupling capacitors, for GPS module, MCU, etc.

The voltage on their terminals does not exceed beyond 4.2V in worst case.

I was wondering if there is any significant reason (Apart from cost) to choose larger footprints for an smd MLCC especially in my case.

EDIT: What is the main difference between two sizes considering same capacity, voltage and dielectric?


texts:
I have 0V/1.6V input signal comming to my device and I have to use it as  'Enable' signal to one of the ICs, which accepts 0V/3.3V levels.

To build such a level shifter generally I know I should connect input to transistor base, +3.3V to collector and 'Enable' to emitter.

Additional requirements are:
1) I have to take minimum current from the source as possible -> base resistor must be big enough.
2) When there is 0V on the input, in reality there will be some small signal due to capacitance -> base resistor can't be too big to discharge it.

Could you please help me with it? I don't have practical knowledge, I don't know how to build it.


texts: XL6009 Boost Converter as 8V Camera (DSLR) External Power Supply - Camera not Turning on

texts:
I need my camera Canon EOS 7D Mark II powered in terrain for a long period of time (10 + hours, mostly idling). I bought a dummy battery with 5V to 8V boost converter (camera uses 7.2 Li-ion battery), which "almost works". I can turn on the camera, switch on live-view, record video. but I can't take pictures. I suspect DC-DC converter can not handle current spike needed (it should be up to 3 A) for taking pictures. I did-not crack open it for now, so I have no idea what it consists of.  Prior power source should not be problem, as I tried powerful powerbank and also mains adapter. But that is no the issue now.
So I decided to switch the provided DC-DC converter with more powerful one. I bought DC-DC boost converter based on XL6009E1 IC (image and schematic below). Note that I am not certain with 0.1 microF capacitor values, but other should fit. It should handle input current of 4 A according to product description (it would burn without heat sink/cooling I guess, but I only need short spikes of high current).

Problem: After hooking up 5V on input od boost converter, setting 8 V on output, and delivering it to camera trough dummy battery - nothing happens. Camera won't even turn on. I measured 8.00 V while connected. There is also small current: 0.01 - 0.02 A. Measured current could be no-load current (18 mA according product description.
Polarity was correct. I suspected boost converter to be defective, so I hooked a small DC motor on output. It ran, measuring almost 1A of current.
Questions: Why the boost converter is not delivering enough current to camera? Am I doing something wrong? What should be changed? I do not believe that there is more than 1 A of current needed for turning on the camera. Smaller (and assuming also weaker) original boost module was capable of it.
Update: I measured current flowing to camera when switching on with original boost converter that came with dummy battery. It slowly rises to 0.7 A @ 8V. It was measured only with multimeter several times, this was the peak. Also, I tried to take a picture, and it spiked to 1.5 A @ 8V then error message on camera appeared. While this error message is really the most probable caused by not sufficient prior power source, it does not explain why the camera is not even turning on with XL6009 Boost Converter. It can successfully output 1.5 A @ 8V (tested od bigger DC motor).


texts: Multiple receivers in a 4-20mA current loop?

texts:
How can I design a system that would allow me to put multiple receivers on a single 4-20mA current loop? Assume that I have design control over only one of the receivers.

Sensor:

Loop powered (2-wire)
Supply voltage: 12-28VDC
Max Load: 250 Ohms @ 12VDC (500 Ohms @ 24VDC)

Current Receiver Design:

250 Ohm resistor to ground
Loop power supply ground is connected to ADC ground


texts: How can I drive a NEMA 17 stepper with a raspberry pi

texts:
I purchased a NEMA 17 stepper motor for a small home project, and I want to drive it off a Raspberry Pi.

I purchased a DRV8825 Stepper Motor Driver Carrier thinking that it would drive the stepper, but I think I got the wrong thing. The motor driver looks like it needs a higher voltage than I want to provide to the stepper, so I'm worried it would fry my stepper if I hooked it up to a higher voltage power supply.

A tutorial I found recommends using a L293D IC to drive a stepper, and I can follow these instructions, but I'm not confident that the directions will apply to my stepper.

I'm a total newb at electronics, so anyone that can point me at what the best way to drive this stepper would be my hero.


texts: From UCC28950 webench design data I have approached a vendor for making a transformer for Phase shifted Full Bridge DC -DC converter. Now before giving order to vendor, I want to gather data on how to make an SMPS transformer and How to validate it.


texts: Where are the rare earth elements in electronics?

texts:
I have really some trouble to find information about where to find rare earth elements in electronics. When I look at my electronic board, I open several datasheets, I am not able to find any rare earth elements. There is no information. Where are they?
The 17 rare-earth elements are cerium (Ce), dysprosium (Dy), erbium (Er), europium (Eu), gadolinium (Gd), holmium (Ho), lanthanum (La), lutetium (Lu), neodymium (Nd), praseodymium (Pr), promethium (Pm), samarium (Sm), scandium (Sc), terbium (Tb), thulium (Tm), ytterbium (Yb), and yttrium (Y).


texts: Can I using nichrome wire to light a candle electronicaly?

texts:
I want to be able to create a set of candles that light automatically (for a presentation) however it's almost 100 candles and I need an inexpensive solution. I know that nichrome wire get's hot when you pass current through it but can it get hot enough to start a candle. I figure that I could wrap the wick with the wire to get it started (I don't need it to out afterward).

The question is: can I heat up nichrome wire enough with less than 12 volts of electricity?


texts:
Switching regulators and LDOs are not an option, for complex reasons.

Are there any MCUs which can tolerate a 14V supply voltage?

I'm currently looking at 4000 series logic to do what I need, but I would much prefer an MCU.


texts:
I have a machine that has a circuit more complicated than this, but this to make things simple:

The voltage source is 24 VAC coming from a PLC, and it has more than 100 × (bulb + resistor + switch).

How can I insert one relay in this circuit to be able to perform a command outside this circuit when ONE or more switches is closed?

simulate this circuit – Schematic created using CircuitLab

My question is: Why this circuit didn't work?

Relay model: RMI 45

Datasheet:
http://www.farnell.com/datasheets/1430520.pdf

Update: When one of the switches closes, the lamp don't go on and the relay keeps closing and opening frequently.


texts:
I was trying to understand the non-ideality of op-amps, and specifically how the input bias current is modeled. The image was taken from a nice Youtube tutorial (Mateo Aboy - DC Offsets).
The input bias current (\$ I_{b+} \$ and \$ I_{b-} \$) are the undesired currents generated from within the op-amp (i.e. a base current or a leakage gate current heading to the first transistor). The op-amp has to have these current inside the op-amp internal circuitry. But when \$ I_{b+} \$ and \$ I_{b-} \$ are modeled with superposition, these bias currents flow through the compensation resistor \$ R_C \$ instead, and none into the op-amp as if the op-amp is ideal.
I can't make sense out of this model: the input bias currents are the currents flowing into (or out of) the inverting or non-inverting input, and there should be a (theoretically) measurable current at the input terminal. There should be a \$ I_{b+} \$ entering a non-inverting input, and a bigger current \$ I_{total} - I_{b+} \$ flowing through \$ R_C \$ into ground (i.e. current divider).
How can one assume \$ I_{b+} \$ existed internal within the op-amp but when modeling the circuit assume it all flows through \$ R_C \$?

[EDIT]
Shouldn't the input bias current shown in the above circuit (b) be modeled a bit more like the following circuit? The D1 diode is an idealized component that takes zero voltage drop and functions to restrict the direction of the current to only flow into the non-inverting input (hence, input bias current)? Otherwise, if without the diode, we'll run into the dilemma where we're modeling an input bias current that does not flow into the input - make no sense.


texts: Speed of a mosfet triggered directly from the logic pin of an Attiny85?

texts:
I have a an N-Channel Mosfet soldered to an adapter board and connected to PB4 of an ATtiny85 via a solderless breadboard. The mosfet currently switches the ground leg of some other low power components, less than 50mA.

DMG2302UK-7 N-Channel Mosfet
ATtiny85 spec sheet

From the instant the ATtiny code decides to fire an output on PB4, how long does it take for the Mosfet to be to the full on state? Reading the spec sheet it looks like the mosfet should take 3.3nS and the Attiny should take 1.5 clock cycles (150nS at 10mhz). The internet tells me gate capacitance comes into play too, but I doubt its a simple RC calc?

I don't need to be exact I just need to make sure im in the right ball park and dont need some sort of specialized driver circuit or a different mosfet. I am trying to send a signal at a khz speeds, and am seeing like 0.03s delay for this mosfet to trigger. I just want to determine if it is an issue with my code or with the circuit.

Thanks!


texts: Can I use full-size 64/72 bit DDR2/DDR3 memory module with CycloneV hardware controller of 24 + 24 bits?

texts:
I thinking of using Cyclone V FPGA and its hardware memory controller:

There is "Cyclone V FPGA Multiport Memory Controller" document from Altera:

http://www.altera.com/devices/fpga/cyclone-v-fpgas/overview/memory-controller/cyv-memory.html

  Configurable memory width of 8, 16, 24, 32, and 40 bits

The PDF "External Memory Interfaces in Cyclone V Devices" has more details http://www.altera.com/literature/hb/cyclone-v/cv_52006.pdf

  Hard Memory Controller

  The Cyclone V devices feature dedicated hard memory controllers. You can use the hard memory controllers for LPDDR2, DDR2, and DDR3 SDRAM interfaces. Compared to the memory controllers implemented using core logic, the hard memory controllers allow support for higher memory interface frequencies with shorter latency cycles.

  The hard memory controllers use dedicated I/O pins as data, address, command, control, clock, and ground pins for the SDRAM interface.

On the page 36 "Hard Memory Controller Width for Cyclone V E" there is the text "Table 6-16: Hard Memory Controller Width Per Side in Cyclone V E Devices" which says that in the selected 484 version of Cyclone V E there are 24 pins (top) and 24 pins (bottom) for memory data (DQ) with hardware memory controller.

So, I have two hardware memory controllers with 24 bit width each.

Can I use them to use the full-size DDR2 or DDR3 memory module (like modules used in my PC or in my notebook). According to several pdfs, the 240-pin PC modules (and 204 pin notebook modules) are usually configured as 512Mx72 or 512Mx64. I read this Module configuration as memory with 72 (ECC) or 64 (non-ECC) data pins.

I think, that count of hardware pins in my FPGA is less then data width.

Can I merge two hardware controllers of 24 pin into single 48 bit controller and use the module?

Can I use module, if I don't drive part of pins?

Can I split module into two parts, using left part independently of right part, each part with own addresses?


texts: Switchable Multiple Channel Current Sink

texts:
I want to create a multiple Channel Current Sink which is switchable. I already have 2 designs, but i am not realy happy with both of them. Maybe some of you guys have a Idea how to improve one or a totally different idea. The main idea is to trigger LED for a specific period of time with a defined current.

Number 1:

This is the one with the internal Multiplexer.I know what you will probably think about the Mux in the control loop. But my intention is to Shut down the DAC to 0 so there is no Voltage Output of the OPA. Also i want to preload the Rset to around 1 mA to shut down all errors and offsets. Later i want to out this error out by just put 1 mA more on the DAC Output.

Number 2:

This is the one with the external MUX and a dummy Load. The dummy load starts the circuit and later i switch one led channel on and take the dummy laod off. The sink is most of the time on. Here is my problem that the FET´s are floating at the beginning and if a LED fails or burns through they are not on a specific voltage level.

So to put it all together:
Problem number 1: MUX in control circuit
Problem number 2: Floating FETs


texts:
So , I found this exercise online :

I am having having a hard time finding the conducting values of the diodes . Will D1 conduct for Vin>=10 and D2 for Vin<=-10? And what will be the value of Vout when both of the diodes don't conduct? (Assume that both of the diodes are ideal ,V2=Vin and V=Vout)


texts: I want to be able to digitally switch the input of a line-level preamplifier. I was considering using relays to physically connect or disconnect each source to the input of the amp, which would be perfect in terms of fidelity. But is that sort of overkill? Would CMOS transmission gates be good enough? Am I overlooking something far simpler and more obvious? Thanks.


texts: Shield arduino for electrical interference

texts:
I have an Arduino UNO controlling two high voltage relays via a switch. It also reads out a third relay, which is controlled outside of the Arduino. My setup looks like this:

With the following representing circuit:

When I turn on the soldering station, the Arduino reads an interrupt on pin 2, where the switch is connected. This also happens when the 12V source is replaced by a car battery. The soldering station is also not grounded. Due to these facts I concluded it must be some kind of electrical interference, probably EMI. I have been looking all over the web to find a way to isolate the Arduino from the interference but I can't find a proper way.

Does anyone know how to shield the Arduino for the interference?

Thanks on forehand.


texts: Multiple power supplies for a high-current electronics project

texts:
I'm doing a project combining different electronic modules with an Arduino Uno. There are five semi-independent pre-assembled modules that I need to power, and with whom the Arduino interacts with (detecting if some inputs are on or off by tension - by "hijacking" some LED power sources, and cutting the module's power supply via a transistor).
A single module works fine while powered by an Arduino for prototyping, but I need to find a solution with sufficient current for the five modules. The modules and currents are:

4 HDMI switches (drawing around ~150mA each)
USB switch (2A max)
Arduino Uno (sources say 500mA to 2A, but I'm counting on 1A to be stable enough)

First approach
In total I'd need around 3.6A 5VDC, maybe 4, to power everything. My first approach was to look at supplying power via a voltage regulator (I have a 12VDC 5A power brick that I want to use) to convert it to 5VDC, but common voltage regulators stop at around 1/1.5A, and I know putting some regulators in parallel is a bad idea.
I've seen solutions like this one using an LM7805, so would something like this be a good approach, provided it could reach 4 or 5A?

Other (and maybe favourite right now) approach
However, I have some concerns about concentrating that much current in a PCB surface, so I though of an alternative approach, where each module would have its own voltage regulator supplying power to it. This would result in 6 "power supplies" *, each with its own voltage regulator, albeit all drawing power from the same power brick.
My concern here is whether that could lead to some "interference", given that the Arduino will have to measure tension in the modules, and that measured voltage will not be supplied by the same regulator as the Arduino's. Moreover, the Arduino will also control a transistor that cuts the module's power supply (though I could use some kind of relay or MOSFET for isolation in the later case).
So the big question is whether 6 "isolated" modules, each with its own regulator, can "interact" (for lack of a better term) with each other, namely for controlling transistors or sensing eachother's tensions, and if they share the same ground, given that the DC current comes from the same brick.
Thanks for your attention!

*: The four HDMI modules could use the same supply, bringing the total to 3 supplies, but I digress.


texts: What is the purpose of a resistor in series with a potentiometer?

texts: I assume the 100 Ohm resistor is in series with the potentiometer so that the circuit is not shorted if the potentiometer has a value of 0 ohms, however, I know that will not affect the circuit because of the Zener diode. Can someone explain thoroughly please?


texts: Using a clock to increment a counter which drives a mux?

texts:
I am trying to program this functionality onto a Xilinx FPGA; however, when I program it to do this, I get no output.

My situation is as follows:

I have 12 bits of data (in parallel): the first 6 bits are a sequence of 1s and 0s, and the remaining 6 are useful pieces of data. The goal is to send these 12 bits serially to a different FPGA (which will have a state machine programmed in order to decode the data).

The way I have been trying to send the data from the primary Xilinx FPGA is to have all twelve bits as inputs into a mux. The selector will be driven by a counter (going from 0-11) that is itself incremented by a clock pulse.

In theory, this doesn't sound too difficult for me... I have implemented it using Xilinx System Generator and, in simulation, it works fine.  However, when I actually program the FPGA, I get no output! I have the FPGA hooked up to an oscilloscope and have verified that it worked. (The verification process involved comparing a 1MHz sine wave with 0 and pulsing whenever the sine wave is greater than 0; this worked.)

I am wondering if anything I am doing sounds wrong at first listen... Thanks a lot.


texts: Ultrasonic Cleaning for RAM and CPU after water damage

texts:
After suffering water damage from a broken pipe. I would like to know if I can use Ultrasonic Cleaning in order to clean the CPU and RAM.

1 x Thread Rripper 2990WX (2000 Euros)
8 x 16GB Ballistix RAM (800 Euros)

The motherboard suffered the most. It cannot be saved. However, the CPU and the RAM could be.

Questions

What is the best solution to clean the RAM and CPU?

Is this a suitable Ultra Sonic Cleaner: 42KHZ + 50oC temp


texts: Diode letting voltage through in circuit simulator - bug or real?

texts:
I'm pretty new to electronics, and so I've been modelling my circuits in a Falstad's circuit simulator.

I noticed something which I did not expect, and am curious - is this effect real, or is this a bug in circuit simulator?

I've reduced my circuit to the smallest circuit that shows the problem - shown here

My understanding of this circuit is that the diode should block the current from flowing from the right (12v) side to the left side, so the circuit becomes a 5v power source, connected to a resistor - should be at 5v.

Note: I want to understand what's happening, more than I want a solution. I know I can put in a smaller resistor, to make the problem less.


texts: Sharing ground between two fully bridge rectified AC signals

texts:
I am designing a device which has two AC input signals. The Input signals are as follows.
A - AC Signal A
B - AC Signal B
Com - Shared Neutral for above inputs

Voltages of these signals could be anywhere between 12V-35V(rms,50Hz). These signals are used as both power and control signals for the device. The functionality of the circuit is like following.
AC signal applied between A and Com - Do Task X
AC signal applied between B and Com - Do Task Y
AC signal applied between both A,Com and B,Com - Do Task Y (Same as above)

Since it's hard to work with AC unregulated signals I wish to convert them to DC signals(and also DC power for the circuit will be drawn from the signals) and probably implement the rest of the circuit with logic gates or transistors. For this reason I need them to be rectified and share a common ground. I have designed following circuit with two bridge rectifiers and common ground, but it's no good. When AC is applied to Com and B, on the negative half cycle current conducts through the rectifier of signal A. I would be extremely grateful if someone could guide me for a better implementation.
I have also tried to create some other designs but couldn't make it to functional one.
Edit: I prefer a design without a center tap transformer

Edit:
I have modified the design with the suggestions from @Kyle B and now I have a +Vcc GND -Vcc type power supply which is absolutely fine for my design.
Edit:
With the excitement of voltage outputs I forgot to measure currents. When I measured them later it turned out to be order of hundreds which suggested an open circuit. Later I found out there is indeed and open circuit through diodes in this circuit. So this design not longer valid and I'm back to any new suggestions again :-(


texts: Simulating ADL5536 Gain Block with Ideal Amplifier

texts:
I'm trying to simulate the ADL5536 Gain Block in LTspice. A link to the datasheet can be shown below:

http://www.analog.com/media/en/technical-documentation/data-sheets/ADL5536.pdf

Analog Devices doesn't have a SPICE model for it, only the S-model parameters, but I think I found a rough workaround, and I wanted to ask here whether it was feasible or not.

The gain was presented as roughly 20.1 dB, round it to 20 dB, and I was thinking of using an ideal op-amp to simulate the gain ideally as shown below:

simulate this circuit – Schematic created using CircuitLab

For a rough gain estimate, assuming same impedances, modeling it as an ideal non-inverting op-amp should lead to the 20 dB gain based on calculating the voltage gain in decibels. Does this seem correct based on my understanding, or am I missing something?


texts: Measuring the dampening sinusoidal wave of a simple LC Tank circuit?

texts:
I've been trying to do the simplest of things...measure the decaying sinusoidal wave of a LC Tank circuit on a breadboard.

I've created an "inductor" out of a coil of copper wire I wrapped around a pen. I have a 1uF capacitor connected in parallel with this "inductor."

I charge the capacitor with a 9V battery, then remove the positive lead which should produce a sin wave.

I have the ground of my o-scope connected to one lead of the capacitor, and the positive lead attached to the other lead of the capacitor.

On the o-scope (analog, mind you)  I just see what looks like the capacitor discharging its current over time. (I.E. I see 9v steadily decreasing to 0v.)

What could I possibly be doing wrong with such a simple circuit?


texts: I have a customer requirement to enable and disable enable pin of regulator using GPIO. We a delay circuit in between. Delay is required both for powerup and power down condition. Can someone suggest me a circuit for powerup and power down delays using transistor or mosfet.


texts: Searching for the name of a rotary switch/push button switch combination

texts:
I'm looking for a switch that combines a rotary switch and a push button switch. The only one I could find is the "Würth Elektronik WS-RPTL 481RV12172100" which is not exactly what I was hoping to find.

I am really surprised not to find more of this kind of switches, as for instance modern microwave ovens seem to use them a lot (like the Samsung MC32F604TCT, I think).

Am I only missing the correct name for this kind of switch or are they really that rare?


texts:
I got an ESP-12Q ESP8266 module and I am trying to upload Arduino firmware on it. But I can't even get any response from the module at all. No LEDs anywhere are on, I don't even know if the thing is dead or if my wiring is wrong. I get not even a single sign this thing is alive on the serial monitor. I have tried different baud rates. I don't know if it is a faulty unit because I can't tell if it is on. Absolutely nothing.

I have wired it up as follows:

I have also tried using 10k resistors to connect between the GPIOs and the VCC and ground but no luck. I also tried using the Arduino UNO to act as USB to Serial (tx-tx, rx-rx) but nothing.

I am about to toss this unit in the bin because I am completely at a loss right now. Any help would be greatly appreciated.


texts: How to make on/off switch for popcorn maker?

texts: I have a popcorn maker that when you plug it in it just starts working. Theres no on/off switch and it's kind of annoying. When you unplug it you always get a big blue spark which seems kind of dangerous to me, it might not be but it seems like it would be. It has a standard 2 prong AC power cable. How can I make an on/off switch for this without breaking it or shocking myself?


texts: Is there a way to suppress the output when compiling multiple vhd files except for errors?

texts:
I have a compilation script I run before simulating on QuestaSim 10.7:

vcom -vhdl -2008 my_lib -check_synthesis src/mux.vhd
vcom -vhdl -2008 my_lib -check_snythesis src/clockdivdeby2.vhd
...

I receive an output on terminal as follows:

vcom -vhdl -2008 my_lib -check_synthesis src/mux.vhd
-- Loading package STANDARD
-- Loading package TEXTIO
-- Loading package std_logic_1164
-- Loading package std_logic_arith
-- Loading package STD_LOGIC_UNSIGNED
-- Compiling entity eop_counter_tb
-- Compiling architecture rtl of eop_counter_tb
-- Loading entity eop_counter
End time: HH:MM:SS on Mon, DY, YEAR, Elapsed time: 0:00:00
Errors: 0, Warnings: 0
vcom -vhdl -2008 my_lib -check_synthesis src/mux2.vhd
-- Loading package STANDARD
-- Loading package TEXTIO
-- Loading package std_logic_1164
-- Loading package std_logic_arith
-- Loading package STD_LOGIC_UNSIGNED
-- Compiling entity eop_counter_tb
-- Compiling architecture rtl of eop_counter_tb
-- Loading entity eop_counter
** Error: src/mux2.vhd (LINE NUMBER): something something, bad syntax
End time: HH:MM:SS on Mon, DY, YEAR, Elapsed time: 0:00:00
Errors: 1, Warnings: 0

I was wondering, is it possible to suppress the output message of loading and compiling and timing? I would like to know the errors and warnings however. Something like this:

vcom -vhdl -2008 my_lib -check_synthesis src/mux.vhd
Errrors: 0, Warnings: 0
vcom -vhdl -2008 my_lib -check_synthesis src/badfile.vhd
** Error: src/badfile.vhd(LINE NUMBER): something something, bad synthax
Errrors: 1, Warnings: 0

I do know that the whole output can be logged. However, I wanted to know right away if there are any errors instead of opening the file and searching for it in the log file.


texts:
Why area capacitors considered ideal for systems that require excessively high current(in the magnitude \$ 10^6 \$) for short pulses? Also, how can they manage to output high current in that range without causing severe damage? High current at that magnitude would lead to massive heat. I can't imagine the system to function more that a few ms, is a second or more even possible?!

How can they manage the capacitors energy storing capacity & how they are connected(series/parallel), with respect to the resistance of all the wires & terminals connecting everything, Incredible systems.


texts: I'm a mechanical engineer so I don't know much about electric circuits and power generation to begin with. Can somebody explain what a harmonic is in the power grid and what is the reason why it is bad? I understand it comes from non-linear electric loads but what does that mean?


texts: What arguments to use to switch from graphical design entry (HDL)?

texts:
I am an experienced FPGA designer with background in Information Technology and therefore used to GIT and Test Driven development for FPGA designs. Of course flow was automated by Make scripts, so using GUI was never necessary.
I have even used a bit of goodies that MyHDL offers (like testing directly from python using Numpy, using signal classes etc).

In my current job the section is using graphical design entry for HDL.

I had a presentation where I presented my concerns about this design approach. Of which is that binary files are hard to version, inefficiency of graphical entry and lack of automated tests.
The lack of scriptability of the tool (the resulting design must be generated using GUI...) which leads to inefficiency.

But the old electrical engineers seems to be reluctant to even consider using plain VHDL with scripted Flow not speaking about allowing me to use MyHDL on new projects.

My question is therefore for seasoned EEs how they were if ever persuaded to use plain-text entry? What kind of arguments should I use?
And for younger what arguments they used to get rid of the graphical HDL atrocity?


texts: What sampling frequency do I need for a non-periodic signal?

texts:
I have a load cell attached to a crimping press (20mV Full-scale differential voltage). The press presses down on the load cell when it's crimping a terminal and the load cell outputs a differential voltage.

It doesn't explicitly state in the screenshot but the pulse lasts for about 35-40 ms. The operator can be fast enough that he is able to crimp two wires in approximately a second. I am considering using an ADC with an integrated PGA but I'm not sure what sampling frequency I should choose. I can see the benefits of sampling this as fast as I can because I can average the results to reduce noise but I don't know where to draw the line - would 2kHz be enough? 10kHz? Perhaps I haven't look hard enough but it seems there aren't many high speed ADCs with integrated PGAs.

An alternative way would be to use a PGA like PGA281 (with excellent drift and error specs) along with a 16-bit or so differential ADC and sample at, say, 200kHz and average 50 points (effective sampling frequency: 4kHz)

The peak detection itself is just a simple if statement. I start sampling as soon as the operator presses the foot pedal and continue sampling for approx. 300 ms (this is the window in which the pulse is bound to appear).


texts: how can power line 'orientation' influence electronic equipment?

texts:
Ok, long story short.
I have a new TV that occasionally switches on all by itself. In case anyone is wondering it's a Sony XH90 and this problem is documented on www. Not trying to go into details about this, makes no sense.
The thing is, someone suggested to me, try reversing the power plug. For the heck of it, I tried without any hope. But, to my surprise, it actually solved the problem!
I am an EE and know a few things about power line, electronic design, SMPS design. This TV is not grounded (double isolation design), same as all other equipment attached to it (exclusively through HDMI).
I know power line has line and neutral, but even then, how could reversing the power plug possibly make any difference. Any ideas?
Final conclusion
This issue was in fact a non-issue. What i described did happen, but not again after the TV had been rebooted by unplugging it, nor after re-reversing the power plug. It must have been a software bug that disappeared after a reboot.
Nevertheless, someone trustworthy did suggest the solution (where there's smoke, there's fire), and Andy aka did give a very likely solution in case the issue would have been real. Kudos to Andy for what he wrote, i will certainly keep his thoughts in mind whenever applicable.


texts: Trying to use MUCs to sample data from IMUs over bluetooth at a specific sampling frequency

texts:
I am designing a data collecting system and I want to be able to collect the data from both sensors at a rate of 500Hz. I was wondering if anyone could help me calculate/prove this mathematically before I actually by the parts? I want to prove my design before I can purchase the components.

I am using two Rfduinos, two MPU 6050’s and a BLE wireless dongle for the computer. The first Rfduino will recieve data from its IMU and send it to the second IMU. The second Rfduino will also receive data from its IMU and then package both its data and the first Rfduinos data and send it to the computer.

My thought process:
If every degree of freedom is 2 bytes. That means 12 bytes from each sensor. So the first RFduino needs to send 12 bytes (Plus an extra 2 bytes most likely too designate what kind of data it is and who is sending it ex. FF, 00), meaning the second Rfduino will need to send 24 bytes (Plus the extra “signature” bytes to allow the computer to interpret the data). If I estimate around 28 bytes sent just to be safe at a rate of 500Hz, that would be 14000 Bytes/s or 112000 bits/s (112000 Baud). Since the bluetooth can communicate at a max rate of 115200 Baud, does that mean I will just be shy of 500Hz sampling rate?

Also, I know the MPU 6050 has a theoretical max sampling rate of 1kHz over I2C but is there a way to determine the actual sampling rate? With fast mode I2C (400kHz), will I be able to sample the IMU’s fast enough for every degree of freedom’s raw data?

In conclusion, can anyone help me determine whether there are any factors that would limit my sampling rate and then help me calculate (or estimate through calculation) the  sampling frequency?

Thanks!

EDIT: I am using this to collect raw accelerometer and gyroscope data from different parts of the body. The faster the sampling frequency, seems to mean the more accurate the data because we use the discrete data to create a "continuous" data curve.

Parts:

Mpu 6050
Rfduino
Ble Dongle - http://www.robotshop.com/ca/en/usb-ble-link-bluetooth-module.html


texts: Is there a 10X probe compensator BNC, but with out the probe?

texts:
Is there such thing as a compensation BNC like the ones found on 10X probes? I'm basically taking about a BNC coupler with a resistor and a adjustable cap in it. I guess it would be like a standard 10X BNC attenuator but with the variable capacitor,  so it can be used to connect a standard BNC to alligator clips cable but with the added ability of being able to reduce capacitive load and compensate for cable capacitances?

I've looked all over and I don't even know what to call such a thing, compensator?

Thanks


texts: Good LCD for clean mounting in hobby project?

texts:
I'm refurbishing an old Kenwood amplifier--- removing the old faceplate and adding a board with a microcontroller, multiplexer IC, digital pot for volume control, IR receiver, etc.

I'm also considering adding a small display of some kind, either a seven-seg, or graphical. I know there are various ways of cutting a square hole in metal or plastic, but it seems like most of the displays (example) expect to be mounted behind a cleanly-cut hole, unlike most switches and buttons and other penetrators, which are inserted from the outside and have an overlapping flange that covers any problems with the hole.

So my question is, how could one make such a flange for an arbitrary LCD? Can they be bought? Are there hobby-ready LCDs out there which include it?

What about alternatives, such as mounting dark-tinted plexiglass over the entire front-face of the device? Can anyone comment on their experience with such an approach?


texts: System Verilog seq.ended or seq.triggered

texts:
Some verification tools support the following System Verilog code:

wire s = seq.ended;

Where seq is an SVA sequence. Other tools do not support this code. Is this "standard SV"?

If not, what would be an equivalent way to define such a wire in "standard SV"?


texts:
I have a piece of code that toggles the GP2 pin on a PIC12F615 and suddenly it started producing a weird waveform, I'm not sure what I've done that could cause this. I isolated the code that toggles the pin alone in a new project to see if I'm doing something wrong but I still get the same result.

Here's the waveform:

And here's the code

void main(void)
{
    __delay_ms(10);

    TRISAbits.TRISA2 = 0;
    while(1)
    {
        PORTAbits.GP2 = 0;
        __delay_us(55);
        PORTAbits.GP2 = 1;
        __delay_us(55);
    }

    return;
}


texts: Sawtooth wave generator using 555 timer working at low frequencies

texts:
So I am trying to develop a saw tooth generator using a 555 timer however I have a couple of problems regarding the calculations.
The saw tooth generator is built in this way:

The mathematical way to describe the behavior of this is by the following formula:
 F = (Vcc-2.7) / (RCVpp)

where Vcc is the voltage from the power supply, R stands for Resistance,
C for the capacitor and Vpp for the output voltage of the wave generated.

My problem is that I need the saw tooth wave to last 60 seconds which is 0.016 Hz, a really low frequency, also it will use a 12V power supply. The voltage Vpp I have no idea how to find it and it is exactly the value that is affecting my circuit. According to my research the Vpp value comes directly from the input voltage used, this means the R and C values won't affect it, therefore I can't use the equation to Vpp's value. How can I find the Vpp value?


texts: How can I change an LTspice .model parameter during transient simulation?

texts:
I'm trying to make an idealised boost converter using current feedback. I want to simulate changes in duty cycle, which is controlled by the Vt and Vh of the switch.

I managed to use .step to see the effect of various settings, but I can't figure out how to change it during simulation. I tried to define a voltage source and do things like Vt={V(thr)}, but could not get it to work. How can I do this?


texts: I know almost nothing about electronics, but I'd like to intercept the power going to a small speaker and use a relay switch to close a speaker connection on a completely different, but more powerful device (a home outdoor sound system).  I used a multi meter to discover that the original speaker works with a voltage of 1.4 VDC but I can't figure out how to get the amperage.  Is there a generic relay switch that would work in a situation like this?


texts: Opamp outputs high DC finite voltage when input signal is low

texts:
I have in the past asked the same question, but it has not been resolved yet.
Here I will try to describe it in a better way:

We have a signal coming from a optical receptor (SFH250V broadcom). When we measure the "dark signal"(when it receives no light) it produces a mere 2-3mV. When a full light PWM light beam is produced, it emits a PWM of about 230mV of amplitude. (I measured that and checked the datasheet, everything till now is fine).

That same output signal is sent to a classic op-amp lm358.
That op-amp is powered with 5VDC on pin 8.
Pin 4 is grounded. Here is a schematic:

simulate this circuit – Schematic created using CircuitLab

The problem is the following: When we plug it that way, but we don't send a signal, the output signal of the op-amp is 420mV. When we send the signal (which was approx. 220mV) it rises up to 680mV.

How I expected it to behave:
1- the 20mV noize would double because the G = 2. so when no signal would be sent a mere 50mV should appear.
2 - The amplified signal would be of 440mV approx.

I tried to change the gain. With a gain of G = 10, the background DC becomes 2.4V and when the signal is sent is rises to 3.2V.

Anyone knows what is going on?

EDIT#1: Here are some scope traces as asked.

EDIT #2:
I've listen to @Entrepreneur and i've put a resistor, but on the ground as the "art of electronics" suggested.
Now, I get a square signal with the right duty cycle, which wasn't the case before. Plus I don't have a super high voltage noise, but this comes to the cost of a lower output signal than expected.

simulate this circuit

Here are my measures on the scope now:

WITHOUT SIGNAL INPUT

WITH SIGNAL INPUT


texts:
On what parameters does the Ic collector current of a transistor depend upon, base emitter voltage or base current?

I know that BJT is a current controlled device. But still we have graphs that show that Ic changes when Vbe changes.

Which one should I consider?


texts: Getting CPU clock signal out of computer (as to measure externally)

texts: I've been searching on the internet some clock generator module capable of reaching up to 1GHz, when I just realized that the machine I'm using to search has one CPU with its own 2.5-3.0 GHz clock...  Is there a way to extract the clock signal out from the motherboard? Something like a spot where I can nail my oscilloscope probe and say "look dude, that thing going up and down at 2.5GHz is my computer's clock!"


texts: Level shifting between SD Card and Lipo-powered microcontroller

texts:
I have an ATtiny861 microcontroller powered directly from a Lipo battery.  My circuit is designed to operate on supply voltages from 3V - 4.2V (bonus if it tolerates up to 4.6V).

I need to interface with a MicroSD card, which works around 3.3V.  I'm using this datasheet from Kingston as a reference (feel free to point me toward a more authoritative spec).

I'm looking for suggestions on sourcing (or building) a level shifter that tolerates the entire 3V-4.2V range on one side, and 3.3V on the other.  Initially I looked at the TXB0104 but it's inappropriate because it requires one side always remain lower than the other.  (I suppose I could run my SD card under-voltage, eg. at 2.9V, but I'm hoping there's a better way).

Also note I'd like to minimize part count, routing complexity and footprint (in roughly that order).

A few more details:

I only need to read the card, and am limiting myself to SPI mode.  That means three unidirectional "output" lines from the uC to the SD (CLK, CMD, CS/DAT3), and one unidirectional "input" line from the SD to the uC (DAT2).

Running the uC at 3.3V isn't an option I'm considering.  It spends most of it's time sleeping, and periodically wakes to see if activity is required.  I figure putting a linear or buck converter between the battery and uC would likely waste some power due to conversion losses during these periods.  It would also necessitate a redesign of some other parts of my circuit.

I'm powering the SD card with a 3.3 buck regulator (PAM2301CAAB330) which is shut down when I'm not reading the card (nor using other devices sharing the same enable line).

I could probably do a quick-and-dirty hack by wiring the input directly to the uC, and the three outputs through voltage dividers.  It might work at "typical" values, but would violate the min/max specs of the components.

Some helpful tidbits from the datasheets:

uC input HIGH min: 0.7 * Vcc (so down to 2.1V)
uC input LOW max: 0.2 * Vcc
uC output HIGH min (@3V Vcc): 2.5V
uC output LOW max (@5V Vcc): 0.6V

SD Vdd: 2.7V - 3.6V
SD input HIGH min: 0.625 * Vdd
SD input LOW max: 0.25 * Vdd
SD output HIGH min: 0.75 * Vdd
SD output LOW max: 0.125 * Vdd


texts: Making a neat, cost effective, efficient job of supplying 24VDC and 5VC

texts:
I'm making a device for industrial control that will internally use 5VDC (for the controller/RPi) and 24VDC (for everything else, sensors, interfacing with the industrial kit etc). The housing will be plastic, vented (passive cooling). The options I'm looking at all seem slightly sub-optimal, and it feels like this must be such a common problem with industry kit generally running higher voltages than micro controllers..

For power supply I'll need 5V/2.5A and 24V/2A. I believe I could use one of the following routes:

A dual output PSU like a Meanwell RD-65B and mount it inside the enclosure.

Pros: tidy, single AC cable into the enclosure, cost effective.
Cons: brings AC safety considerations into focus for the device, generates all its heat inside the enclosure;

Dual output brick power supply outside the enclosure

Pros: solves every problem I can think of
Cons: can't find one with the current capacity required. Could make one by separately enclosing one for step 1) but it doesn't seem cost effective when adding in the build time and extra components

A single external brick power supply providing 24v 5A+ outside the enclosure and internally a DC-DC converter providing 5V from the 24

Pros: neat, and 24v 5a bricks are common
Cons: the DC-DC regulators I've looked at have efficiencies around 80% and I presume the rest ends up as heat inside the enclosure. Means the 24V PSU needs to be larger current capacity than necessary which bumps the price up and regulators aren't so cheap either - this is the most expensive option

Two different external power supplies

Pros: Cheap, easy individual replacement if they break without opening the enclosure, cost effective
Cons: looks messy, needs 2 AC outlets

Am I missing anything?

What's the typical route chosen when different voltages are required? (I'm guessing from e.g. PC manufacture it's option 1) Is option 3 as wasteful in terms of efficiency as the specs sheets lead me to believe? 5v, 2.5A = 12.5W, divided by 0.8 is around 16W so am I right in assuming that 24VDC -> 5VDC will incur a wastage of 4 watts with an 80% efficient converter?


texts: Help me about the complex power in circuit analysis?

texts: In circuit analysis, the complex power is S = P + jQ. For the avarage power P, we can use wattmetter to measure P. But how we can measure the reactive power Q in the circuit ?


texts:
I built the below video amp & it worked nicely.But it is One in One out video amp.
http://www.learningelectronics.net/circuits/video-amplifier.html

Now I want One in TWO out Video distributor.I added the red colored capacitor coupled but did not worked.Without the capacitors it is working nicely.

Any Ideas?


texts: How to make a simple manual gengerator that can produce a 9 volts of electricity?

texts:
I have a project from my subject which that project was to create a manual generator that can produce up to 9 volts of electricity. I've been searching some samples that is homemade manual generators, but I've found they are powered only by batteries, and using a dc motor..

Is there any other samples of manual generator which is not powered by batteries or with the help of dc motor or should I say manually operated?
   And it can produce electricity up to 9 volts? and also can you give me the materials to be used in creating the generator?


texts: GPIO on base of transistor not scaling linearly

texts:
This is really a followup to a previous question to provide an updated schematic and photograph at the request of a commenter on that question.  I'm not sure if there is a better way to provide such an update to a question but here it is anyway...

I have the following circuit:

simulate this circuit – Schematic created using CircuitLab

When I measure the voltage across R2 I don't see the 18V being supplied into the collector of transistor scaling linearly with the value of the PWM GPIO of the NodeMCU.  It ranges from 9.35V with the GPIO at 0 (i.e. off) and 17.14V with the GPIO at 1023 (on "full").  With a GPIO value of 512 it reads 13.16V.

I tried my best a photograph of my set up:

About the only thing that is not clear in the photo I think is that the resistor "above" the transistor is between the GPIO with an orange wire and connects to the base (middle pin) of the transistor.


texts: Altium Designer: How do I scale the output gerber file generated by Smart PDF into 1:1 ratio?

texts:
I'm trying to export a PCB layout PDF from Altium Designer 13.2.5.

When my PCB design is open, I click
Menu > File > Smart PDF...
to open the PDF generation wizard. Throughout the wizard, I do the design output settings, and at the end of the wizard a one page PDF containing the PCB tracks, pads and holes is generated, as you see in the image below.

However, the page of this PDF is in standard A4 size (210mm x 297mm), my PCB layout is stretched to entire page and the original scaling of my PCB is lost. My PCB manufacturer requires it to be in unit size. I couldn't find a setting for this in the Smart PDF wizard or anywhere else.

How do I print the PCB layout of my design on an A4 paper in 1:1 scale?


texts: What tool can make a nice 3D image of a via?

texts:
I found this graphic somewhere on the web, but now I need to create a similar illustration for some training, but with a 16 layer board having traces coming in on other layers etc.

What is the easiest/fastest/cheapest tool to do this? What tool was used for this graphic?


texts:
Total beginner here,

I'm trying to build an "LED Chaser" circuit using an IC (CD4022BE) that counts to eight (from zero to seven, and then it wraps around and goes back to zero).

Before trying to fit all eight LEDs onto a breadboard, I figured I would try it with two LEDs first. The datasheet labels the eight relevant outputs as "0" through "7", so my LED "0" is connected to pin 2, and my LED "1" is connected to pin 1. The idea was that I start at "0", then send in one CLOCK pulse to jump to "1". Then, since I have only two LEDs connected, I would have to send in seven more CLOCK pulses before the cycle repeats and my LED "0" lights up again.

I came up with the following circuit:

I'm powering the whole thing with 9 Volts, just because it seems convenient.
I've tried to implement this circuit on my breadboard but I'm getting behavior I don't understand and didn't expect (Hint, I have no idea what I'm doing). When I connect my battery, my LED "0" lights up as expected, but when I connect a jumper wire from +9V to pin 14 (CLOCK), nothing happens (I was expecting it to turn off LED "0" and turn on LED "1").

Across the terminals of my battery I measured 8.79V (OK). I measured 8.79V across VDD and VSS (Don't know if it's supposed to do that. I guess ICs don't have voltage drop? Does that sentence even make sense?). I measured 2V across LED "0". To my surprise, I measured 4V across LED "1" (Oops), and finally, I measured 4.04V across the potentiometer.

I don't really understand where these numbers are coming from. I have absolutely no intuition when it comes to electronics, so any help is appreciated.


texts: Is there any passive component holder similar to a fuse holder?

texts:
Below is a fuse holder from Keystone. As far as I know, it allows the user to replace the fuse inside easily when it is needed.

My question is, is there similar holder for regular SMD passive components, such as 0603 holder, 1206 holder and so on?

For example, If I would like to test a part of my board with different capacitors, I could simply plug out the capacitor and replace with a new one, instead of soldering and unsoldering it. I know soldering a component is really not much of work, but i am imaging with such holder, it is much faster for testing, it saves time to replace components without any extra eletrical equipments.

I tried to search it on Digikey but only found fuse holders and LED holders. I guess there must be a reason why this is not popular (or it does exist with some special names?), thus I hope someone can maybe give me a explanation or insight of this idea?


texts: can you power a load and charge a battery with a votage source 2x the battery voltage?

texts: I'm sorry, I am very new and green to circuitry, and probably frustrating to read. I have a hypothetical question about a circuit with a 6.6 v charging source that is both charging a 3.3 v 100 ah lithium battery and powering a 3.3 v 100 amp load. I have read that chargers with more power output than their circuit batteries will power the load and charge the battery with its excess. I also know that charging lithium batteries must be charged at its stated voltage for safety reasons. My question is concerned with safety and feasibility. Is it possible for this 6.6 v charging source to feasibly power the load at 3.3 v and safely charge the battery at 3.3 v? Thank you for your time and help.


texts: Asynchronous induction motor, current in stator

texts:
My question is, how was \$ I_{stator} \$ found out?

Y -connected 3-phase 4-pole induction motor has \$ R_r = 0.5\$  Ohm , and is supplied from a 480V l - l, 60Hz source. It is connected to a load that has load torque \$ T_L   = 3 + 1.3 \cdot 10^{-3} w^2 \$, with \$ w \$ the rotor mechanical speed in rad/s.

Here's full problem with data and solution with no explanations:

I know the general idea of how asynchronous induction motor works, but I don't quite know about equivalent circuits and how everything connects to make proper calculations.

For instance, is this the equivalent circuit model for stator?

If yes, then is it simply \$V_s (\frac{480}{\sqrt(3)})\$ divided by the equivalent impedance of the whole circuit shown?

In the problem, impedances need to be re-calculated to look like \$ X_m \$ and \$ X_{ls}\$, the way it is done is by formula: \$ L_m \cdot f_{stator}\$  (in rad/s). But in my case, can I just use given 60Hz?

So \$X_m\$  would be \$L_m\$  \$\cdot f_s  = 250mH \cdot (60 \cdot 2\pi)  = 94.25\$ ?

What's the difference between \$w_m\$ (mechanical) and \$w_r\$ (rotor speed?) in this very similar problem? I thought it meant the same thing, yet in formula for calculating \$w_s\$ (speed of stator), both of these properties are used, as if they're two different things. So what is mechanical speed then?


texts: What are the important considerations when choosing a pass transistor and bias resistor for a buck regulator?

texts:
The MC34063 datasheet shows this diagram for a buck configuration with an external (NPN) transistor (in order to be able to handle higher loads than 750mA):

Neither the datasheet nor the application note provide any guidance in choosing the transistor or the bias resistor connected to it. What are the important criteria when choosing a pass transistor, other than current capacity, and how should the bias resistor on the base of the transistor be sized?


texts:
I'm trying to drive a motor for an academic project, using the circuit in the image.
The STM32F4 Discovery board that I'm using in this phase of the project produces a 30Khz PWM at 3V, that is correct (checked with an oscilloscope) but the motor does not turn on.
Anyone can suggest me some motivation for this behaviour?
Thanks,
Daniel


texts:
is it safe to add an activity LED to an USB charging cable in parallel?

full story:
I've recently bought one of these glowing USB charging cables, but it died after a few months of use so now i am thinking to make myself a replacement with a single activity led.

Here it is my plan:

take an USB extension cable and cut a bit of insulation in the middle of it
cut the power and data wires and strip both ends
solder a 330ohm resistor and a led in series with the power and ground wires like this:

simulate this circuit – Schematic created using CircuitLab

The cable will be used only to charge mobile phones, because i think the increased current usage may cause issues to USB controllers.

EDIT: still looking for an alternative design providing some form of current-passing indication using discrete components only.


texts: CSR8645 3.2 bluetooth module audio output merge negative pins

texts: I want to use this module with my car aux in which is has 3.5mm 3 pole jack. This module has separate negative pins as LN and RN. I need to merge and connect these pins to aux in common negative pin.


texts:
I am using EM18 RFID module. When I connect Module alone to 12v supply it works great but when I connect raspberrypi also to the same 12v supply to power (12v to 5v using buck converter) then EM18 module dosent work as good as it worked when connected alone to the supply(range decreases, read in every attempt is not guaranteed).
What could be the possible issue ?

And please don't tell me to repost this question on Raspberrypi stack exchange :)


texts: Darlington Transistor TIP142 same type but different values

texts:
I have a bunch of Darlington NPN Transistors TIP142 that are removed from two separate identical boards. The 1st one have the TO−218 CASE (left side of the image) and the 2nd the TO−247 CASE (right side of the image)

https://www.onsemi.com/pub/Collateral/TIP140-D.PDF

With the Diode Test when I measure the Base-Emiter with N-Probe to Base and P-Probe to Emmiter with the TO−247 I get about 1.368V for all of them, but the same measurement for the TO−218 is OL for all of them (Please note that the multimeter with no probes connected is also indicate OL).

The resistance between them is for the TO−247 about 3.56KOhm and for the TO−218  about 15KOhm.

The other measurements seems to be identical.

So I am really confused and I wonder if some of them are faulty.

  Edit: In my opinion since there are two resistors in series between
  Base and Emitter there should be a voltage drop. In the TO-247 case my
  multimeters show OL maybe because there is no much current to draw to
  show any measurements. Note that the resistance in that case is about
  ~15KOhm instead of the 3.56Kohm of the TO-247. The datasheet referes
  that the 1st resistor is ~8K but for the 2nd just ~40 ???? what ?


texts: Refrigerator noise mysteriously stops when someone stands close to it

texts:
So there is this rattling noise that a refrigerator makes from time to time. That wouldn't be weird, that's what refrigerators do.

What is spooky about this is that when you walk close to the refrigerator about 30 cm or 1 foot of distance, the noise stops. As soon as you move further back it starts again. If you move back again it stops and so on. This works with 100% consistency.

It seems to me that it has something to do with EM field, but what and how and why, answers to those are a complete mystery to me.

Does anyone here have any idea, what could be the source of the noise and how it could be potentially fixed? It sounds kind of unusual, not like the typical sounds it and other refrig. make.

To supply some information, it is a fridge with a freezer in the top part and there is a microwave resting on top of it. Next to it is television and espresso machine. (That probably isn't relevant at all, but who knows! Better to include information)