texts: Interpreting a voltage requirement given both as a range and as a percentage?

texts:
The following table contains the input power specifications for a laser printer:

(Source page 1-9)

As you can see, the volts listing is given both as a range, "100-127" and also as a percentage "±10%".  What is the meaning of this?

i.e., does it mean the actual range is 90 - 139.7 VAC? Something else?

Why would they choose a seemingly ambiguous format for this information?

Note, I don't think they have just copied this from national standards. e.g., Wikipedia says

  "In the United States and Canada, national standards specify that the
  nominal voltage at the source should be 120 V and allow a range of 114
  V to 126 V (RMS) (−5% to +5%)."

I'm pretty sure this printer was designed for sale in that market. This doesn't seem to match the range given in the documentation.


texts: How to determine the gain of this OP AMP circuit?

texts:
I need to calculate the gain of this op amp circuit. It look like a differential op amp circuit, but i only have one resistor in the feedback loop, R3.

This circuit functions as a Voltage level shifter by adding 2.5V DC offset to the AC input.

UPDATE:
After making changes, (removing the 1K across the inputs and replacing the 47K by 100k all over), this is the result.


texts: Calculate total impedance in RLC circuit with L and C parallel

texts:
I am trying to find the total impedance of this circuit but im not getting the right answer. According to my notes the total impedance is 1002 Ω, -86.6°.

This is the method i tried:
I got

Xc = 111.1, -90° => 0-j111.1

Xl= 125, 90° => 0+j125

R = 60+j0

then from here ive tried multiple different methods. ive done ((Xc*Xl)/(Xc+Xl))+R. Just adding Xc+Xl+R then converting them back to polar form. Nothing i try give me the right answer. What am i doing wrong here?


texts: Help deriving the transfer function of an LC circuit?

texts:
I have the LC circuit below. I believe (but I'm not certain) that this is a 3rd order filter. Since there are two capacitors and 1 inductor.

The circuit is a passive low pass pi filter. The component values have been chosen so that the cutoff frequency is 15kHz. The input is from a signal generator with a source impedance of 50ohms (the resistor shown).

I need to derive a transfer function for the circuit but I'm not sure how, since I don't know the order of the system. The Bode plots of the system are below:

Can anyone help me derive the transfer function of the system using these Bode plots?


texts:
If I charge a electrolytic capacitor outside of a circuit and let it sit on my bench top, it drains over time.   I found this question on S.E. but that capacitor is in-circuit.

Where does that charge go?
Does it get transformed into some type of energy and then lost over time?


texts: Simple rig to measure current drawn in very short bursts?

texts:
I have a microcontroller based circuit that sleeps most of the time and works in short bursts of less than 1 milisecond and I don't have access to a digital osciloscope so I could record this. I only have a simple one channel analog scope.

So, how did they do that in old times? Is there a way to set up some external circuitry to measure current that is drawn in short bursts?

What I'm thinking is a small low side resistor with a capacitor in parallel, but I'm not sure...


texts: Instrument amplifier output continuing drifting

texts:
I'm using AD8226 to amplifier differential signal coming out of a load cell, the output of the AD8226 goes straight into the AD7190. My load cell is full bridge with output impedance of 350 Ohm, excited by 5V.
Here is my schematic for the AD8226.

The IN1- and IN1+ is connected to the load cell. Here is just one channel, there are four channels of these. All share the same 5V with four load cells. The 5V is generated by MIC5205-5.
The schematic of Vbias is down below. All four channel share the same Vbias.

The simulation in LTSpice seems fine. However, as I receive the PCB and test it, I found that the output of the AD8226 is continuing drifting.
The output of the AD8226 is continuing rising, about 0.1mV per second. I test another channel, the output of that channel is continuing falling by the same rate. And I leave it there for a while and one channel just broken. Why is that happened?
All the component in the board is SMT except for the AD8226 and 249ohm gain setting resistor. And all the resistor is 1% and all the capacitor is 10%.
The load cell is connected to the board by a screw terminal, and some channels are not always connected to a load cell.


texts: Dolby HX PRO implementation on existing tape recording deck

texts:
I'm experimenting the implementation of Dolby HX PRO's IC into an old stereo Fostex tape deck to improve high frequency and headroom capabilities.

HX PRO works as a dynamic processor with the BIAS current of the deck (without it this would have always the same intensity).

The small circuit analyzes the HF content going from the output amp to the heads and attenuates the BIAS accordingly, preventing saturation.

So BIAS INPUT has to be deviated from the same path going to the ERASE CURRENT head, and the INSERT POINT is the summing point where BIAS and SIGNAL OUT were mixing together - the circuit analyzes SIGNAL OUT HF content and regulates BIAS thru VCA's OUT giving it out in the same node just before the RECORD HEAD.

Each IC (uPC1297CA) manages two channels from, obviously, the same 100kHz BIAS sine wave coming from a common oscillator on the System Control Board.

Despite the circuit is pretty simple to develop, I'm reaching the issue when checking on the scope those weird, relatively high voltages on the channel amplifier board whereby I want to insert the HX PRO function.

MAIN OSC has a voltage of approx. 26V p/p and the node where I would expect to insert the compander function (the asterisk on the schematic below) will show 100V p/p, giving more than 120V p/p on the ERASE HEAD OUT.

Yes, I'm assuming these are currents but these voltages are pretty unusable with the HX PRO.

Here we have the max. voltage capability of 4Vp/p for both BIAS OSC input and SIGNAL input. The main supply is 18VDC referenced to ground and I would expect to bias these signal at a middle point thru the supply swing or use a dual +-9 supply as I see about some Technics tape decks.

I think to need some kind of transformation for the BIAS IN and the SIGNAL IN/OUT node, taking care about the 100kHz frequency involved into.

So I'm asking help from the community, appreciating their kindness in advance: How to handle these high voltages to be managed from the uPC1297CA circuit that needs no more than 4V p/p?

The first image relates to the Channel Amplifier Circuit related to the BIAS path and the SIGNAL+BIAS node (marked with asterisk) path from the SIGNAL AMP OUTPUT to the RECORDING HEAD.
The second image shows the application circuit of the Dolby HX PRO which has a very similar displacement in the majority of the HX PRO tape decks available at the time.

In the while I prepared the complete HX PRO circuit board to be implemented in my Fostex E-2 - I've found the hot nodes too - where I'm expecting to change the three heads with those of another recorder brand - so another adaptation in experiment!
The transformers I took are the original ones found on some cassette decks (the majority) and these are yet variable coils, I have some very thin copper wire and a lathe but no proper experience in winding those so small variable coils.
As yet said, the scope shows an incredibly high voltage when measuring bias from the oscillator but that tension is not there - I tried to measure with a voltmeter and to light up a led diode, we are under 2V for sure (instead of 100V I can see on the scope).
I can provide you the recording amplifier diagram only because Fostex didn't released the main board schematic nor the reproduce amplifier schematic.
There isn't so much stuff on the reproduce board, bias goes directly into the recording heads as I see from the connector bus located between the recording amplifier to the repro amp.
The bias oscillator is located on the main board and as I said no schematics :( I can just measure it empirically but my scope is giving me the fake reading of 100V.


texts: Self-oscillation in a commercial RF amplifier

texts:
I purchased several 50 ohm (in/out), 35 dB gain photomultiplier tube (PMT) amplifiers from a vendor assuming I could use them to read out the voltages on my PMTs.  The amplifiers are AC coupled with a 2k pull down resistor before the coupler.  To avoid RF interference (these PMTs are very sensitive to FM radio stations), I placed a metal box around the PMT and connected the amp via 50 ohm SMA cable through the box.  This gave me a relatively good output with only a moderate amount of 100MHz FM, so I designed a larger box for both the PMT and amplifier thinking I could shield both at once as well as cut down on cable losses.

However, when placed in the box with the PMT, the amplifier oscillates at its maximum output voltage at almost exactly its -3dB frequency (~ 1.6 GHz).  Outside the box (but with identical cabling length, power supply and load), but the PMT inside the box, its stable.  Outside the box, using an extra meter of RG58 cabling (higher source capacitance), its still stable.  If both are outside of the box however, its unstable.  This happens even when the PMT is unpowered.  I swapped amplifiers/PMTs and observed no difference.

I'm not an expert in RF, but I'm assuming this is some kind of parasitic coupling between the amplifier input and output, but I don't understand why putting a box around the the PMT prevents this.   I'm also a little surprise that the amps have so much trouble with the PMT (~20 pf, 100 MOhm).

Am I doing something foolish?


texts: Confusion with figuring out voltage regulator maximum input voltage

texts:
I will use this 12V voltage regulator which in my case marked as MC7812ABT and TO−220 package. And I want to use it for a 12V 16mA load where it will regulate 24V supply to 12V. In the datasheet there is a section which confuses me:

There is 19V, 27V and 30V ect. mentioned. In my case the output will be 12V, can the input voltage be 24V?


texts: Shematics of the BeMicro CV eval board from Arrow

texts:
Where can I find the complete schematics of the board?

Arrow sells an ultra low cost FPGA platform with a Cyclone V device on it for around 30$.
Ok, for that price it has the bear minimum: 2 buttons, 8 LEDs, several connectors, a flash memory, a DDR3, power supplies, SD card slot, etc...

This is just fine for getting started and learning basic FPGA design.

But, the only datasheet I can find is the following : official schematics link

Unfortunately, this document does not include the whole board. Some part of it, such as the MAX V CPLD, the FTDI USB chip as well as some connectors are not included. Do one of you has access to the complete schematics? If yes, is it possible to share it?

I do understand that the MAX V part is the included debugger/programmer. But what I do not understand is: why keeping this hidden?:

We have access to the full gerber files, thus it's easy BUT VERY TIME CONSUMING, to redraw the full schematics (except for the exact passive component values, but it's not rocket science here...).
The real IP that has to remain proprietary and hidden is the CPLD configuration, not the routing around it!

It would be interesting to know how the USB is connected to the FTDI, and if we can use it as a communication channel to a PC software. I know that I can use a virtual JTAG debugging channel to do this, but there might be other ways. By keeping this part hidden I just have no idea of what I can do.

A better approach would have been to keep the MAX V code secret, but disclose the complete schematics. I would still consider the MAX V as a black box with proprietary magics inside, but I would be able to use my eval board the way I want to.


texts:
It's been awhile since I've worked on editing schematics, and I can't seem to find the answer to a question I'm running into when editing my current schematic.

In Altium (or schematic software in general), there's the option to create a Port. The options are Input, Output, Bidirectional, or Unspecified.

Normally, I use Bidirectional, but I've reached a point where I'd like to specify a specific direction for clarity.

How should I be interpreting the direction? Is it:

Input: Input into the Port

Or:

Input: Output from the Port


texts: I've looked at the various simplifications that can be made for signal flaw diagrams to combine branches; however, I can't work out how one can apply a transformation to simplify the following configuration.


texts: Rat Race (Hybrid 180°) Scattering Matrix

texts: why the S matrix of a rat race is the following one? Which is the reasoning for determining it?


texts:
I am trying to increase the current available from my Adafruit DAC going to a flow controller that needs a control voltage between 0-5V at 4-40 mA, using the included op-amp, a TLV2462CP circuit.

The problem is when I drive a voltage into the IN+ the output voltage doesn't change.
Did I wire this wrong?

Additional Information:
I am using a rail to rail because I need to be able to get to lower voltages such as 0.25V and a high of at least 4.95V to step through all the points for my flow controller. I am reading in voltages using a ADS1115 ADC and a program to record all the data.
Photos of my setup:
Photo1
Photo2]5
[Photo3]6]6


texts: Is there a way to embed/group initial value and switch combinations in LTspice?

texts:
I have a circuit with several ICs and components.
But the circuit will behave differently depending on the inputs or the switches set.

Each time to simulate a combination I have to delete/modify several wires or change the power supply voltage values ect.

Is there a syntax or a way to set some conditions in a short way.

Below is an imaginary example to describe what Im looking for:

For example before running the simulation: just by typing 1 instead of 2 in a syntax, the circuit will change 10 switches and set two power supply voltages to a value which were defined by the user before.


texts:
I want to bias my pulser output which is 0 to 30V pulse train.
(Which means I want to make 30 to 60V pulses)
First, I used a bias T with 30V DC input:

I found that it works as a differentiator which gives the pulse train a negative offset so I can't get 30 to 60V pulse.
Is there any solution to make the pulse train to be biased as I want?


texts: How to efficiently compute the current at each node in a resistor network

texts:
I encountered a academic research problem to efficiently compute the current/voltage at each node of a rectangular resistor network. The rectangular resistor network that I have is defined by two things 1) the regular network topology, which you can consider it like meshgrids with one unit resistor on each edge; and 2) the knowledge of the state of each node (bad or good). For example, a 2x2 resistor network of my type (with all good node) is

simulate this circuit – Schematic created using CircuitLab

3x3 resistor networks of my type with all good nodes and one bad node(2,0) are given below.

simulate this circuit

In practice, a resistor network I might have to deal with is of size 300x500. I wonder whether there is some efficient method to compute the current/voltage at each node, when the good/bad nodes are known and the two nodes connected into the circuit is (0,0) and (299,499). I guess there should be some existing methods to this type of questions. Can anyone kindly help me?


texts: I'm trying to use 2 attiny85, one with an IR transmitter and one with an IR receiver (2 pins). I can't figure out how to use the attiny85 with the receiver. Help would be appreciated! If it is not possible to do it with a 2 pin IR receiver, advice for a 3 pin one would be fine too. Basically, I'm trying to let the attiny85 with the receiver do something when it senses the one with the transmitter is on. Thank you.


texts: What happens when you use internal+external pull-up resistor?

texts:
I was working with an Arduino One and this rotary encoder from SparkFun. Then, for no good reason, I put three pull-up resistors, one for each input pin (pin 2, 3 & 4) facing the encoder, like this (only pin 4 is show because small drawing space):

But then I got all kind of problems. Sometimes I could not read the encoder, sometimes I got the push-button pin firing when I just rotate the shaft, sometimes it works randomly, etc. (It's seem to me that behavior was fixed at boot time).

I eliminated the three resistors, and all returns to normal, but, as far I know, this encoder is a simple one; just three switches. I think this is the correct equivalent circuit (just for one pin, the same for the other two):

So, what I'm doing wrong? Did I misunderstand the encoder?

Notes:

My circuits/sketch is working fine. I can read the encoder & push-button.
I'm not using interrupts, just polling in a timer fired routine, at 5-10 ms intervals.
I tested it with internal pull-up on and off.


texts: Improve linearity by increasing P1dB by increasing Vds

texts:
So I am using MRF6V2150N as power stage and I was using VDS 28V and increased it to 34V.  I see that the linearity increased since the P1dB shifted upwards. And this also improved (lowered) the IMD3 cause the ACPR also got better.  I want to know if this is true, normal and make sense.  And if so, is there a reference that I can find to back it all up for a report?
THANKS!


texts: Does the resistance of EMITTER-COLLECTOR changes according to the base current? Or, let's have a constant base current, which is producing a constant (almost) current. Now is this correct to say the emitter-collector resistance is almost zero, since it's passing current? I am asking this because when I'm supplying a base current (but there is no collector supply voltage) and touching the emitter-collector with continuity checker, it beeps, so it feels like at that time the resistance is almost zero.


texts: Is there any PCB design software/extension that can do automatic components placement?

texts:
I made a lot of home made PCBs, but I have a great problem concerned about the design, I am just an electronic hobbyist at school so I don't have that mind of electrical engineer to place components in the right spot, I always place the components near to each other (in my point of view which can be sometimes wrong) use the auto router and set back waiting the computer to get the best PCB copper trace design.

well this thing works in a - 5 component - 555 blink circuit, when I started making a little bit complicated circuits (60+ components) having the auto router used, it never complete the traces. I know probably if I placed the components in the ideal spot the percentage might reach 100% but I can't do so.

All what I want is a working circuit I don't mind the shape so is there any software like EasyEDA or Eagle softcad or any extension that places such components in the nearest spot to making routing easier and much faster.

As a side note using my tools, the absolute maximum specs to any PCB board I make is single sided PCB and 0.5mm trace width 0.5mm clearance, I know if i lower these numbers i will get better routing results and I get, but I fail in making the PCB itself i.e:toner transferring, etching ...... and I know I could just use jumpers but I want a software solution.

In short I want an extension or software related to PCB design that can place the components automatically in the right spot to make routing more efficient.(i.e something that always happen to me that a copper trace just is drawn all around the whole PCB to just connect to a near node !!)


texts: R2 Arduino Uno and an R3 Ethernet Shield mismatch

texts:
I bought an R3 Ethernet shield for my R2 Arduino Uno, but I noticed that it has a few more pins than my R2 Uno has sockets. Do I need to buy a different shield?

Arduino UNO

Arduino Ethernet Shield


texts:
I'm a computer scientist, in college I had a (basic) telecommunications course. I've found it interesting, but had afterwards no opportunity to use apply it professionally, which is of course not surprising. However, once in the aftermath of a class, the professor posed a question to ponder:

"How do you think it is possible for a cell carrier to exactly deliver the signal to your phone, even when sitting in a bus with 50 other cell phones around and moving on the highway with high speed?"

Unfortunately, we never got around to obtaining the answer. I've often thought about it for the past few years, but came to no answer. Can someone help out?


texts: How to drive a single 7 segment display with I2C?

texts:
I am looking for a solution to drive a single 7 segment display with I2C. I found some websites that shows 2 or 4 digits with I2C but I didn't find a solution for driving a single digit. I'm making a big screen with 5x4 7 segment displays where I'd like to address each digit with I2C.
Any suggestions?


texts: DVOM nonstop auto ranging resistance on 1 pin of potentiometer

texts: I think this is a newbie question, but I was trying to measure a couple of pots with my new meter, and on one set of measurements (one set of pins) I'm just getting a nonstop auto ranging all over the place. What's going on here?


texts: Condition for the output and input impedance for cascading electronic circuits

texts: For cascading a system that have an output impedance of \$R_1\$ and an op amp that has an input impedance of \$R_2\$ then in order to use a isolated model we need a value for \$R_2\$ that is minimal 10 times higher than \$R_1\$. But why is that?


texts:
Hiah all,

I have a beginner question about boost converters. I would like to model a solar cell using the following equivalent circuit:

 This effectively gives me a current source (constant in the simplest cases but ultimately I want to add variability due to temperature and insolation as well). Now, when I connect a boost converter to the above circuit, I can increase the voltage but not by as much as I would like. Changing the duty cycle makes the input voltage of the converter lower and thus the output doesn't increase... Here's a schematic of the converter:

simulate this circuit – Schematic created using CircuitLab

It also doesn't really make sense (based my limited knowledge of electronics) to join a current source to the boost converter without any modifications as, when the switch is connected vertically (on state), the steady state current over the inductor doesn't change so its voltage is zero. Therefore, the longer the on state (or the greater the duty cycle D), the closer to zero the voltage to be boosted gets before the switch opens again.

How could I easily change my model to overcome this? Can I just smack a capacitor of the right size in parallel between the solar cell and the boost converter? I'm ultimately looking into creating a controller that keeps a steady output voltage with varying load so just choosing a greater resistor as load doesn't really solve the problem.

Any help is greatly appreciated.


texts:
Looking for a simple circuit which output is only active when its input is a low frequency (0.2-0.5Hz) pulse. The circuit output should be deactivated if input is unchanging.

I tried monostable 555 circuit, but its output is active as long as input is zero. I also tried a capacitor between input and pin 2, but then the circuit doesn't stay active when pulsing - it switches off and immediately activates, which is not what I want.


texts: Is the SkyRC B6 Nano charger suitable for charging single 18650's from 2.4v-2.6v

texts:
I have salvaged six 18650's from a laptop we've owned for years.  Battery voltage: four of them are ~2.63v, two are ~2.46v

I have a SkyRC B6 Nano charger (https://www.skyrc.com/Charger/B6nano).  I've wired up a single 18650 cell holder to an XT60, plugged it into the Nano's output socket.

But it doesn't want to charge them - it returns error code 2 (cell number is wrong).

I'm using the correct mode for Lithium Ion; "charge" option (i.e. not "balance charge"); set to "1" cell; I've tried various current strengths including 0.3A and 0.1A.

Is it possible to use this charger (am I doing it wrong), or will I need to try something else?

Normally I use this charger for balance charging a 5C 18650 battery pack (with an additional balance lead).


texts:
Basically, I want a minimalistic pulse generator. I guess I've always like the idea of Avalanche Breakdown to do this. I was trying to do this by using 2N2222's in reverse breakdown mode, link here, but I was largely disappointed with the non-steep turn ons. By that I mean, as the capacitor charges, the load (the LED) already gets a voltage difference. I wanted a steep turn on, as if a mechanical switch has been flicked or a hi-edge square wave from a 555 or something like that.

So now, I've fallen back to using Avalanche Diodes instead of avalanching transistors. I know that Zeners rated at 5.5V and up are generally Avalanche Diodes, so i went for them (using a 1N4735 that I have (@ 6.2V), but below I'm using a 1N4736 (@ 6.8V)). There was a marked improvement. It's almost like the 1N4735 has to have 1/2 of it's rated voltage before there was any difference in the load (R3 + D2), which grew as the capacitor charged to full.

My initial mod is as shown below and I've tried several other variations, but all it does is a delayed turn on and stays that way. Even the turn on is not very steep (grew as the capacitor charged to full). I could only guess that the current from the source dropped by R1 is feeding the load, which means the capacitor has not been fully discharged to allow cutoff to the Avalanche diode. Or, perhaps, the Avalanche Diode's cutoff current is very low, so it's keeping the transistor conducting. I'm not really sure.

I then noticed that there are TVS Diodes that can avalanche at relatively low voltages (3V or so), much lower than the normal Avalanche Diode's 5.5V, labeled as Zeners. I also hope it avalanches steeply. I'm also hoping the "Reverse Standoff Voltage" parameter will act as an effective cutoff when the voltage falls a certain level...

So can I use TVS Diodes like these?

Or maybe there is just a fundamental mistake in my mod??

simulate this circuit – Schematic created using CircuitLab

EDIT: As mentioned below, the diagram above is wrong. The Avalanche Diode is supposed to be in reverse bias.


texts: measuring resistance in a wire with a short

texts:
A couple of questions:  I have a camper trailer that apparently has a dead short in either the positive or ground wires between the battery and the fuse panel.  Someone told me to measure the resistance of the hot wire and ground wire from the fuse panel back to the battery.  He said if the wires are good the resistance will measure zero ohms.  I measured the resistance in both wires and they measured zero ohms.  If the wire did have a short, what happens to the ohms reading when I measure the resistance?  Is there no reading on the ohm meter or does the number of ohms measured rise dramatically?

The fuse panel:  When I removed all of the fuses and add them back in one fuse at a time I found one fuse in the panel that when I replace it, it causes the main fuse to blow.  Yet when I measure ohms across the fuse panel from the positive terminal to the negative terminal I get a reading of zero ohms.  If the fuse panel is bad why would I get a reading of zero ohms?


texts: In common collector amplifier, we know that the collector is commons since it is connected to AC ground. Now, the characteristics of a common collector amplifier is that it has unity voltage gain, to be exact, it is less than 1 due to internal resistance of the transistor, and has high input impedance and low output impedance. Now, the problem is, whenever i try to add a 8 ohm load (my speaker), the voltage gain drops drastically. I thought common collector amplifier is immune to loading effects since it is use as a buffer. What is happening? (It appears to me that it is suffering the same fate as common emitter (which drops voltage when a load is connected to it directly))


texts:
I want to implement phase angle control for a single phase ac fan. To achieve that we need a ZCD circuit interfaced with a microcontroller to get a pulse at zero crossing. As our circuit has some space constraints, we have implemented the same  using PIC 18LF45k40 which has built-in ZCD circuitry which generates pulses at Zero Crossing.
Below is the circuit for implementing zcd-

The above circuit is referenced from Technical Brief document - Link here

As you can see, the circuit has a common ground with the AC Neutral which makes the circuit bit questionable as the whole circuit has to be treated as live and raises safety concerns. (Please correct me if I'm wrong)

Putting the above concern apart, the problem I'm facing is the pulses generated from microcontroller is not stable. It swings in the x-axis(time) in the oscilloscope. The code for generating pulse is as follows -

void __interrupt() ZCD(void)
{
   if(ZCDIE && ZCDIF)
   {
        LATA1 = 1;
        enableTimerInterrupt();
        ZCDIF = 0;
   }

    if(TMR0IF)
    {
        TMR0IF = 0;
        counter++;
        if(counter==switchingValue)
        {
        counter=0;
        disableTimerInterrupt();
        LATA1 = 0;
        __delay_us(200);
        LATA1 = 1;
        }
    }

}

The ZCD Input when the ground is not connected with neutral is a plain DC line. When the ground is connected with Neutral, sine wave superimposes on the DC line as shown below-

The ZCD in pin gets the following waveform when neutral and dc ground are common -

Following are my questions -

1 - Is the ZCD waveform expected this way? There is a very limited resource available on this issue.

2 - The below is the circuit which I've implemented for Zero Crossing. Is this circuit safe and practical?

Triac circuit -

3 - Please go through the code and let me know the issue.

4 - Please suggest any circuit or app note which implements the zcd.


texts: What is this thing called "LCD interface" found in MCU datasheets?

texts:
When browsing ARM MCU datasheets I often find a thing called an "LCD Controller" or "LCD Interface" and I'm wondering what it is and how it works.
It's present on the LPC3130[link|datasheet] and referred to as "Integrated 4/8/16-bit 6800/8080 compatible LCD interface"
I think it's a sort of controller for common bus used in Displays.
Questions:
1.What is the "pinout" of the bus? What do the lines transmit? I want to now how this works.
2.What sort of LCD is this able to control? Graphic? Alphanumeric?
3.Does this mean the MCU has an built in GPU inside to control the Graphics?


texts: Why microcontroller takes many clock cycles to start up with PLL clock source?

texts:
I was looking over the ATTiny85 datasheet and noticed on page 26 that with a PLL clock source, the fastest startup time is 14CK + 1K (1024) CK + 4 ms. Am I misinterpreting what they mean by 1K CK, or is it that the PLL needs time to set up? Compared to other clock sources it seems to take many more cycles.

Thanks


texts: Possible causes for AAA battery to explode

texts:
Today, the AAA battery in my remote control exploded. The "pop" sound is pretty loud. I've been using this remote control for years, and I'm more inclined to believe that it is the battery issue rather than the circuit issue, because if it was the circuit problem, the problem could have occurred a few years back.

From my understanding, the common reasons for an electrolyte capacitor to explode is due to high voltage over the voltage rating or connection in wrong polarity. However, I'm not sure about the reason for an AAA battery to explode. So the question is like what is stated in the title, what are the possible reasons for an AAA battery to explode?

Edit1:
@Russell, the battery connection is shown below, this should be a series connection right?

Besides, the remote control is still functional with new batteries. I took a deep breath while trying this again, the explosion isn't big, but the sound is still a little scary...

Some additional information:

What sort of battery - Alkaline, NiMH, other?
It's Alkaline - not rechargeable
How many AA batteries in remote?
Two
IR remote presumably?
There's an LED, and I have to point it to the air conditioner to use the remote, I think it's IR remote.
Brand of battery?
Energizer
Age of battery (time in use)?
It's not newly installed, my guess is a few months of usage before the explosion.
Was it recharged?
No, it isn't recharged.


texts: Why is SPI Flash memory so limited in max size, and cost way more (per MB) than SD flash memory?

texts:
For example:

SPI Flash largest size is 512MB at $9/ea: SPI Flash prices

vs

2GB of microSD $3/ea (some with $1 shipping): microSD prices


texts: Why is a reference plane needed in differential signalling?

texts: As I understand differential signaling, return current goes via the "-" (minus) line, so why we do we need to provide a reference ground plane for differential signals?


texts: Why SPI Master mode frequency is half of bus frequency?

texts:
I was reading about SPI here On Slide 2, It says,

Maximum Master mode frequency = bus frequency/2
 Maximum Slave Mode frequency = bus frequency.

My obvious question was Why?

P.S. This document is by Motorola, So We can rely...And I have read similar statements in other presentations too.


texts: Is it possible to construct a USB to UART bridge using MAX232 or TUSB3410 IC?

texts:
I am trying to build my own Arduino board. But for connecting it with a PC a USB to UART bridge was required. Even though I can buy it from sparkfun, I wanted to build my own bridge using some sample ICs. I have a couple of MAX232 IC and have ordered some TUSB3410 IC from Texas Instruments.

So my question is, Can I build a USB to UART bridge using either of these ICs. I am willing to buy some basic electrical components locally.

If this is possible I would be very helpful if you could provide me with some detailed schematics and guide me on this one.

Thanks in advance.


texts: Can a high current trace be on outer and inner layers at the same time?

texts:
EDIT, COMMENTS:

TL;DR: Data doesn't conclusively suggest you can do this, but it seems to be worth trying.

The data from IPC-2152 (more in the answers below) is intriguing, but doesn't seem to conclusively say that what I'm proposing is possible. However, it does say that inner layer traces aren't thermally handicapped: in fact, it seems inner layer traces have lower thermal resistance than their outer layer counterparts (at least in still air).

Let's do a quick calculation to see how this would play out, using the following parameters

a common 1oz/0.5oz/0.5oz/1oz 4-layer stack-up
4 equally sized traces of a width that results in a 1 ohm trace resistance (large, yes, I know) for the outer layers and 2 ohms (since the copper thickness is half) on the inner layers.
A 10V potential across the traces

simulate this circuit – Schematic created using CircuitLab

In this case, we would see 10A on the outer layers and 5A on the inner layers. Power dissipation is then I^2R, which is 100W (10A^2 * 1 Ohm) in the outer traces and 50W (5A^2 * 2 Ohms) on the inner traces.

Given that we know the thermal conductivity of the inner traces is likely to be no worse than the outer layers, it looks like it's at least worth trying a 4-layer design, since the key worry (that the inner traces will run much hotter than the outer traces) doesn't seem to be a concern.

===================================
END EDIT

Original question:

I'm doing some high-current (40A continuous in worst case) traces on a 4-layer PCB, and I'm trying to get the space consumption down.

I've had success in the past with mirroring traces -- half of the trace goes on the top layer, and half goes on the bottom. For example, a 1" wide trace would become a 0.5" trace on the bottom and a 0.5" trace on the top.

But what about inner layers? On a 4-layer board, can I do the same across all 4 layers (e.g. 4x 0.25" traces, assuming all 4 layers are the same copper weight)?

My intuition says no -- the inner traces are much worse at shedding heat, so this may become a problem. But then again, copper has a positive temperature coefficient of resistivity, so perhaps these things balance to an equilibrium?

My question, in parts, is this:

Can I distribute power traces across outer and inner layers?
Has anyone done this and had luck/success?
Do the inner layer traces have to be thicker/thinner than the outer layer traces?


texts: How can I control 8 LEDs with a timing delay with only one microcontroller (PIC12) written in Assembly?

texts: I can have 5 I/O pins enabled. I'm just confused on how to control them individually.


texts: Using a 5v voltage regulator - Capacitors necessary? Better options?

texts:
I am very new to electronics. I am learning as I go, and I haven't quite found the answers I need; when it comes to programming, I'm not afraid of mistakes as they happen constantly. With electronics, though, I don't want to have to buy parts again because I fried them!

I am trying to build something that has three different components in it: a 12-volt 4.3-inch LCD screen, a 5-volt Raspberry Pi, and a 12-volt custom device. I've had the idea that I can split the power I need three ways from a 12-volt power supply: one directly to the LCD screen, another directly to the custom device, and one to a 5-volt regulator, thereafter splicing into a USB cable to plug into the Pi. As I've been researching, I've noticed that people say that capacitors in the circuit before and after the regulator are mandatory to keep the current from oscillating.

Question 1: Is this three-way split with the regulator a sound idea, or am I missing something? I understand there is the potential to need a heatsink on the regulator. That's not an issue for me if necessary.

Question 2: Does my circuit require the said capacitors? If so, what kind/quality would be best? I know little about capacitors thus far. Also, I came across this component while reading another question/answer here; maybe this would be better than a regular regulator?

Question 3: Someone who is not extremely proficient in electronics but definitely better than me said that it might just be easier to use one of those 12-volt car USB charger devices instead of a regulator, which makes sense-- USB is a 5-volt world by nature, and I don't have to worry about splicing a USB cable for the Pi; wiring up the car adapter would be easy. And I have plenty of room to allow for a car adapter; the box I'm putting all of this in will be relatively empty for how large it is. Is this a sound idea? Perhaps better/easier/safer for the Pi than using either of the beforelinked regulators and capacitors spliced to a USB cable?

As for amperage, I'm still researching just how much draw the custom device and the LCD screen will need to make sure there is enough current. That's not going to be a big issue, unless there is something I am overlooking about a regulator requiring a substantial amount of amperage more than it gives out... but I don't think that will be an issue. I'm planning to get a PSU with a good amount more amperage than my setup theoretically requires-- just in case.


texts:
I recently bought a lithium-ion battery that has a built in protection for short circuit. I want to power a thermoelectric cooler with it. But when i connect it to the battery it seems that the protection for short circuit kicks in and won't power the cooler. Does anybody know how can i get around this problem? I have tested both the cooler and the battery and they both work, just not with each other.

Link to battery: https://www.sparkfun.com/products/13112

Link to thermoelectric cooler: https://www.sparkfun.com/products/10080


texts: Is the capacitor placed correctly in the schematic?

texts:
I am new to electronics so any form of advise will be helpful.

While trying to build a line-following robot by studying the circuit schematic(as attached), I wanted to find out what the capacitor C1 and C2 are doing.

1) From my beginner's understanding, I am guessing that C1  and C2 each function as a Bypass Capacitor, responsible for ensuring steady current flow to the LED diode so it doesn't flickers(due to the voltage ripple caused by the motors) as the LED diode is used with the photo-resistor sensor for calibration.

2) Also in the same circuit, there is also no capacitors connected directly to the power source and ground, thus I believe the circuit designer have left out dampening any possible voltage ripple(caused by the inductance of the motor and many other factors) for the whole circuit. Or maybe it's just not significant to regulate the voltage for the whole of this circuit.

Please help verify if my understanding above is correct. it will help me progress big time. Many thanks in advance!


texts: Row Column Matrix Problem with Flyback Diodes

texts:
So I had a simple row column matrix which I am driving with mosfets to power solenoid locks like this:

GC is ground via 1.5k resistor

C is 24V via 1.5k resistor

And these are the connectors:
Outputs

So the problem is after putting the diodes in parallel the whole row and column turns on rather than the single designated point I want. What could be causing this? If i remove all the diodes the operation is normal but upon installing the diodes it start to turn the whole row and column on rather than a designated point.
And the weird thing is that at the point where I turn on e.g 3rd row and 3rd column the designated point I want to turn on has 24V across it and the whole 3rd row and 3rd column (apart from the point i wanted to turn on) has 12 volt across it. This only happens with the diodes.

Let me know if further info is needed!

ADDITION:

Working Normally:

Problem with diodes causing whole column to malfunction (with both switches turned on):

Problem with diodes causing whole column to malfunction with single switch :


texts: What is the PAD size required for the Battery negative and Positive pads voltage (min 30v to max 42v) current (min 500 mA to max 15 A)?

texts:
I am creating a circuit for low voltage battery management systems (10s 1p 36v 2.5A battery pack). All the circuits is perfectly done from schematics to Layout.

But i have small doubt in  Battery negative and positive, Charge negative and load negative Pads. for this in schematics i have used a testpoint so that i can modify based on the power constraints.

The battery and load negative will be connected to the board and the Current (min 500 mA - 15A max)and voltage (30v to 42v)  Will pass from B- (Battery negative) to P- (Load negative) on the board during discharge process.

How much Length and width of the Pad size should i give for B- based on the Power (30 v to 42v ) (500 mA to 15A)


texts: My oscilloscope tells me I vibrate at 60Hz. How?

texts:
As I live in North America, my initial hypothesis is that I'm picking the 60Hz from my house's power line.
But, to my understanding, my body can't be a 60Hz antenna (1/4 wave antenna length for 60Hz is ~1250 km.)

I feel like my understanding of "indirect" coupling is incomplete.
Could somebody help me?


texts:
I'm new in electronics.
I'm trying to make a BCD calculator, but I got stuck in BCD subtraction.
I got stuck in: how can I connect multiple bcd subtrator units?
I'm trying to make a 3 digit calculator, but this can only subtract 1 digit.

Can anyone help me?
Thank you in advance.

PS: I've posted the circuit diagram below.


texts: Simulation software to terminate planar waveguides by geometry and material choice?

texts:
There are a lot of electromagnetics software modeling suites out there (HFSS, CST Microwave, Sonnet some I've heard of).

I want to terminate a coplanar GS or GSG waveguide with 50 ohm. I know that sizing a good conductor down to below 100 nm diameter can actually lead to resistance of this size. But as I'm no expert I still have trouble to find the right direction. Based on my question here, I'm unsure besides the 50 Ohm termination, how I have to bend the ground lines at the end. Do I have to use in any case one of above mentioned software to get here a reasonable waveguide without endless trial and error?

The upper left might have the right termination of 50 Ohm, but the reflection happens before short-circuiting signal and ground, the upper right and lower left would be my next guesses for correctly terminated cpw, the lower right GS waveguide, basically this is a mini coil, but would probably not behave like a 50 ohm load for a very broad frequency range. Can those software packages take into account things like skin effect to simulate impedance correctly? Which software should I choose, as far as I've heard Sonnet might be best for planar waveguides and antennas


texts:
I was trying to solve this problem (number 27) and as per the KCL equations I am getting that an infinite number of Ammeter readings are possible.

I used KCL after taking the outer loop as the ground (ideal ammeter means voltage is the same everywhere in the outer loop). I found unique values for the currents in the inner loop but I need one more equation to uniquely determine the outer loop current?

I was unable to simulate this, an error (check circuit topology appeared in EveryCircuit). None of the options are among the infinite solutions I found. Can you help me find the answer?


texts: How to design a no-load detection circuit and auto cutoff if load is not presented?

texts:
How to design a no-load detection circuit, I couldn’t find a reference design,
Is this possible task to perform?
Load is an LED setup, 150V DC, 30mA
If load is not connected to the circuit, power path to the output port should be cutoff,
But when load is connected circuit should automatically release the power to the load.
Circuit should contain small number of components as well.


texts:
I've recently got hold of a second hand Thandar TM355 bench multimeter. It can be supplied by either 6 "C" cells or there's a 2.5mm barrel plug for power. Unfortunately, the service manual doesn't give any more information than that one must use an "approved AC adaptor".

Looking inside the box, it seems that the batteries are just in parallel with the power input making me think that I just need to supply it with 9V DC (6 times 1.5V), but I thought I should check here whether anyone either (a) knows what the TM355 expects or (b) has experience with this sort of thing and can tell me whether my guess is likely to be right.

I presume that the "AC adaptor" that the manual refers to implies some sort of power brick: there's no obvious bridge rectifier or the like anywhere near the input so I assume that it's expecting DC.

So, the question: Is a 9V DC plug likely to be OK, or will it blow things up?

(PS: I hope this is on topic: Although it's related to a specific device, the question is one that I'd expect some electronics professionals to be able to answer, through having used one themselves)


texts: How does a benchtop power supply measure and control current?

texts:
This may be a simple question, but it is something that I can't seem to wrap my head around.

I have a +12v 5A power supply at work which has two knobs, one for voltage and one for current.

There are various devices that upon plugging them in I have to increase the current otherwise they will not work, but when I do this, the voltage level stays the same.

My question is, what exactly is happening when I turn the amperage knob on a benchtop power supply? My guess would be that we are changing the resistance being supplied to the device but I am unsure and would love a real explanation!

Thanks!


texts: NXP LPC 4330 Microcontroller starts up very hot and sometimes doesn't start up

texts:
EDIT 3 The correct solution is shown below, in TurboJ's answer in fact, this exact issue was mentioned in the LPC4300 errata ES_LPC43x0:

EDIT: Nope, sorry false alarm. The new board started doing the same thing:(

EDIT 2: I'm beginning to wonder if poor layout is to blame. The +3V3 rail is shown. Because the board is a 2 layer, I had to forego the traditional power plane and power is provided by a single 6 mil trace. I noticed that the problem never occurred on a board with no decoupling capacitors populated, but started to happen when I added the .1uF capacitors.

I have a board with a LPC NXP 4330 (ARM Cortex M4/M0 dual core) microcontroller, in a TBGA-100 form factor. The power situation is complicated because I have sensors which require precision 4V power, so the main supply needs to be a LDO drop above 4V, so it is powered in the following way:

3.7V Lipoly or USB (controlled through MAX1555 battery charger)
->
4.5V step up/down switcher (TPS63061 integrated switcher)
->
3.3V low-drop out linear (LP38691)
->
LPC 4330

I have noticed that on startup, the micro will start up very hot (too hot to touch) for a second, before settling down to a more reasonable temperature. When it does this, I can communicate through the JTAG just fine and run my application. It will always start up like this when connected to a 4.5V bench power supply (bypassing the switching regulator completely). The surge current is very high, up to a couple hundred of mA, as the spike in temps confirms.

When connected to the switcher (fortunately it is on another board, so it is easy to bypass), sometimes it does not start up. I assume that this is because the surge current is causing the switcher to shutdown because it goes into some over-current mode. If I disconnect the switcher from the load, plug in the battery first, and then plug it back into the load, it will cause the micro to get hot (as usual) and then work.

Is this normal behavior for the LPC 4330? It seems fairly unusual that a microcontroller would take several hundred mA to startup (where is all that current going?) Is there a way to prevent this initial current inrush when the entire circuit is hooked up.

I've included a schematic, I will need to run tests on the supply ramp up on Monday.

Main micro-controller board

Power and USB connector board

Layout showing +3V3 rail


texts: Calculating slip, LSB, and USB for induction motor

texts: Hi How can i calculate the slip, upper sideband, and lower sideband for induction motor with rpm=450, 300 watt , 24 volt, frequency supply= 30Hz


texts: What is a simple method for measuring the physical vibration of a step motor (to STM32) in order to take it to a minimum?

texts:
For a university project we installed a motor that is controlled from a STM32F407G-discovery board through a step motor drive, we experimented with the number of Microsteps options in the drive, and play with the drive/step frequency in the STM32 code to regulate the speed.

Now we are asked to propose a method to quantify the vibration of the motor according to the variation of speed and micro step size.

What would be a simple method to know the vibration of the motor?, we are guessing it has to be very precise because we cannot perceive the vibration changes easily among microsteps.

Thanks in advance to all. this website rocks!


texts:
I started reading control system (book) just a few days ago ,
In the derivations of equivalent transfer function of  Cascade or feedback connections
it assumes that
"The subsystem connected to another subsytem doesn't load it"
But in case of passive systems  mostly there is loading effect
1.Is that is reason
why "only" passive systems are
are not that important for designing control systems

with The use of only passive systems,  can we design any feedback system ? Because I cannot visualize how can a passive system acts in a closed loop, is there any example of it?


texts: Calculating maximum series/parallel configurations for unique resistors

texts:
Say I have 4 unique resistors. How would I calculate all the possible unique series and parallel configurations and thus, calculate all the possible total resistances?
And how can I expand this to accommodate a variable number of resistors?
I first started listing all the possible combinations for 4 resistors, but this was very time consuming and I ended up missing a few valid combinations. Is there some sort of algorithm that can do this?


texts: Can my battery pack provide power for this motor?

texts:
I just made a 7.2V 6-cell NiMH battery back with a 2300mAh rating. Will it be enough to power this motor of an RC car? (I will link the datasheet). At maximum efficency it draws 13A at a nominal 7.2V. How will the battery pack be able to deliver this current when it's current rating is well below that? I have tried reading various articles and reading through motor datasheets, but I cannot understand how it works. Here is the link

I would greatly appreciate it if anyone could help me understand this


texts:
I'm building my home lights with an SMD5050 Led strips.
And I'm completely lost after comparing specs consumptions with real measured data.

So on, I have 5 stripes and 1-to-5 Splitter from my controller:
2 legs for 10m each, both sides fed from the splitter.
5th one is single-feed from a same 1-to-5 splitter.
So, that's properly builded scheme and I don't expect

In total: 10m 30Leds/m for 7.2W/m and 15m 60Leds/m with a 14.4W/m. Oh yes, that's should be 288W and 20A x 14.4V!

I have a Wattmeter, that stands before 220V input of my 15A 12V Led power supply, and I can measure only 90W of consumption in the HARDEST case, which I mean 14.4V output of supply and White permanent color on strips. That's 3 times less than proposed to be (don't counting imperfection of 220-12V transformation).

Why so? Does it mean that I can connect more and more strips, and the power supply will handle it? (Specs for supply is 180W max consumption, so currently it's loaded just 50%).

How to figure out, where the real consumption is? I don't have a reason to untrust my Wattmeter - used it with everything in my home from phone chargers (4W) till AC (800-1200W), and collected data seemed very real..


texts: Water on Li-Ion battery fire: good idea, bad idea, or neutral?

texts:
I always thought (like this guy) that putting out a Li-Ion battery fire with water was a bad idea because of the reaction between water and lithium.

But now I read from one source:

  Lithium-ion batteries contain little lithium metal and in case of a fire they can be dowsed with water. Only lithium-metal batteries require a Class D fire extinguisher.

Is this accurate? Can I really use water on Li-Ion battery fires?

And if so, is this safe for batteries of any capacity, or is it dangerous beyond some mAh?


texts: Motor "load" for 8051 does not change based on 8051 GPIO pin

texts:
I implemented a circuit very similar to the following (original source: 8051 - Can an NPN transistor be driven?
) to control power to a vibration motor from my micro.

I made the following modifications:

Power supply is 5V DC regulated, not 3.3V
R1 is changed to 100K (to try to save battery power)
R2 is changed to 1K (to pass GPIO pin value to transistor easier)
Q2 is TIP31
PowerV is not a separate supply. Instead it is replaced with a 51 ohm 1/2 watt resistor connected to the same 5V DC regulated supply to prevent the rest of the circuitry from overheating or shutting down

I ran tests using a voltmeter with the motor physically disconnected. In my software on the micro, I can choose to make the GPIO pin high-impedance or grounded. This part works. What doesn't work is the voltage reading at the "Load". It's always stuck around 5V no matter what the value of the GPIO pin state is.

I have tested the motor by connecting it directly to 4 AA batteries that are at 75% good status (not weak) and the motor runs flawlessly in that setup so the motor isn't at fault.

I also ran a conductivity test on the motors and that was normal.

What's the best way to fix this without hogging power? The only thing I could think of is that my R1 and R2 ratio is terrible and that I should just make R2 24K since I multiplied R1 by 10 in my design?


texts: Preferences: Male or Female connector on board

texts:
On a prototyping board for use by students, should one place male (pin) headers or female headers on the PCB, considering that most of the pins will be unused most of the time.

I'm inclined to place the female headers on the PCB and have male pins attached to all cabling respectively. This way touching unused, open contacts by accident is less of an issue. But checking through catalogues (Hirose, Molex,..) I see lots of male headers for PCB mounting but few female ones.

Is my reasoning backward? What I am missing?

Conclusion:

Considering all comments of this thread I am inclined to use male connector pins on the board. Doktor J has given a nice example of a shrouded pin header that would even provide some polarization, albeit I will probably use a 2mm pitch for compactness.

Even better if those were side-stackable, that is if I could place like 2x20 holes in a row and have shrouded connectors of different width (say either 2x 2x10, or 4x 2x5, or a single 2x20)  attached. However, this is not possible with the typical box-shape shrouding.

Solution
I just discovered FCI Minitek Headers. These are side-stackable and have polarization and shrouding. I'll go with these.


texts: We have been doing some cleaning up out in the electronics production area and found the "mystery tool" shown in the two images below.  It is made from stainless steel.  The blue insulation is dipped and the black insulation is heatshrink tubing.  I estimate that it's around 10 years old, but that's just an educated guess.  For reference, the quarter is about 1"/25mm in diameter. Does anyone recognize this tool?


texts: Making UART between ATmega32A and the PC :

texts:
I used PL2303hx to connect my PC to the chip and I did the correct connections and installed the driver of the IC and the program I wrote was simulated succesfully on proteus:
But when I do it on the reality the blue LED in PL2303hx blinks every time I send data from the chip to my PC (e.g. if I make the delay time 1 second it blinks each 1 second )but data is displayed is just <0>

the code to just make sure that it works fine :

#define F_CPU 16000000
#include <avr/io.h>
#include <util/delay.h>

int main(void)
{
    uint16_t UBRR_Value = 103;

    UBRRL = (uint8_t) UBRR_Value;
    UBRRH = (uint8_t) (UBRR_Value >>8);
    UCSRB |= (1<<RXEN) | (1<<TXEN);
    UCSRC |= (3<<UCSZ0);

    while (1)
    {
        while (! (UCSRA & (1<<UDRE)));
        UDR = 'B';
        _delay_ms(1000);
    }
    return(0);
}

and the fuse bits CKSEL and CKPOT are set to fit with 16MHz external crystal just like written in the code.


texts: Detecting a low pulse from an electromagnet induction

texts:
I am designing something similar to a coil gun. So what I have is a magnet passing through/adjacent to a coil. Due to the electromagnetic induction, I do get a pulse(triangular) across the coil. However, the amplitude of this pulse is very low to detect, as its around 60mV peak.

I tried using a comparator(LM311) for detecting that low voltage, but noise disrupted the operation, as the noise level was also high.
Is there something I can do to detect that pulse?

Things I thought about :
1. Increasing windings on the coil
2. Using a stronger magnet
but apart from these, is there something that can help me achieve the same?

Currently the coil used is a small sized with about 30 turns of around 23-25 gauge magnet wire

UPDATE: I tried increasing the resistance by adding  a 1Kohm-100Kohm in series to the coil, but it did not increase the voltage much. I also tried winding a coil with more turns but still the max voltage was around 40mv.
Also, here is a video: http://www.youtube.com/watch?v=hajIIGHPeuU  I came across. The current generated in this case is 20uA, which for a resistance of 1Kohm, should give a Voltage of 0.02V. Any other way, I can increase the voltage level. Would having a core help in anyway?


texts: Ultrasonic transducer for NDT short circuit

texts:
i have bought several transducer for NDT test from some manufacturers, but before i tried them, i checked that the impedance between the positive and negative transducer just around 2 Ohm, and it didn't work with this circuit

is it normal? because i have an old transducer worked properly and has around 3 MegaOhm impedance


texts: How to specify a capacitor in Altium schematic as DNP

texts: I am working on a prototype of a project and it involves an antenna. This means that I will probably have to tune this first version a little bit once I get it assembled. To do this, I wanted to place into my circuit a "dummy" capacitor. I realize that I could make a pads in the CAD with the right dimensions, but this wouldn't show up in the schematic. Also, I have seen in schematics capacitors with DNP values. This is what I am essentially looking for. Is there an easy way to do this/best practice? I am a student trying to learn the right way to accomplish these tasks..


texts:
This is the first time I have used this product (an Arduino-compatible robot) and I'm having some trouble. I've done this on 2 different boards now.

I select the serial port, load up the blink sketch....

First time - it loads beautifully and I get the Blink sketch I loaded.

I then change the values for a longer blink....load it and get the error

  avrdude: stk500_recv(): programmer is not responding

I get a pause as though its about to start loading the code....but then the error.

Any suggestions?


texts: Is it better to study semiconductors before electronics devices?

texts: In my university I have no semiconductor course to study. They make us begin studying electronics devices right away (Topics in microelectronics by sedra). My question is should I study semiconductors first ? or Is it okay to get directly to studying electronic devices ?


texts: newbie: comparator adjustable level shift

texts:
I'm trying to build a simple fpga logic analyser and wondering how to best design the input circuit.

I would like to support 8 channels, voltage between 0-5V, with a adjustable threshold range (lets say between 0.7V~2.8V) connected to 3.3V tolerant pins. Not sure what frequency I can hope to achive, as high as possible I guess...

Since I'm fairly new to electronic I'm not sure exactly how to approch this,

My first idea was to use something like a LP38500TS adjustable linear regulator for the threshold, connect that to the inverted input of a comparator and my input signal to the non-inverted and set VCC to a value higher than 5V and then have a voltage divider after the comparator to bring the signal down to 3.3V...

Tried it in ltspice and it looked ok... :) But I have a feeling that there are much better ways of doing this.

Will this design even 'work' in the real world?
What would the easier/better/saner design be? (I'm sure there is one…). Wouldn't surprise me if I'm making this more complicated than it really is.


texts:
I am simulating an ideal inductor in LTSpice connected to a 1Vpk 50Hz sine wave and 1 ohm resistor.

The current through the inductor seems really low, at peak being around 3.2mA

As the current through the inductor should be the integral of the voltage multiplied by the inductance it seems that this should be higher. So why is it this low?


texts:
Based on Detecting a low pulse from an electromagnet induction,
I was planning to amplify a DC sine/sqaure wave, however the peak is less than 50mV.
What is the smallest voltage peak that can be amplified using a DC amplifier?


texts:
I have a couple of cell phones laying around, one of them being this one:
http://www.gsmarena.com/sony_ericsson_elm-3057.php

Is possible to clear the flash memory and replace it with a bootloader and then upload arduino sketches or pic32 sketches(C#/C++).

I got this idea because it is a very cheap platform for developing hardware projects. (You get a screen, buttons, audio I/O, internet, etc, you get everything for a very cheap price compared to what you get by buying each part separately.)

Is it possible to erase the flash memory and install a boot-loader into a phone to use it as an embedded computer?


texts: Does Amp Hour Rating Take Into Account Voltage Drop Relative to State of Charge?

texts:
I'm looking at buying batteries, either 12v AGM or LI-Ion, for use in a backup power system. I have a choice between a Lifeline 8D AGM battery rated at 255 Ah @ 20 hr, or a Victron LI-Ion rated at 160 Ah @ 20 hr.

Because the depth of discharge between the two is different (50% for AGM vs 80% for LI-Ion), I have to wonder if the Ah rate takes into account voltages at different states of charge.

I seem to recall that Ah ratings are based on how long a battery can produce a given ampacity before it drops below 12v. Does that mean an AGM battery rated for 255 effectively only gets 127.5 Ah because of a max 50% discharge depth? Or is it 255 total Ah before it reaches the point at which it's no longer producing 12v? Or is depth of discharge just a consideration for battery life?

I can obviously get much more for my money with the Lifeline AGM 8D vs the Victron Lithiums, but I want to make sure I'm getting the full advertised capacity.


texts:
I have recently bought ICD3 since I think that being able to debug a microcontroller program requires that we be able to see what is happening inside it. I really want to learn this stuff :)

I have a version 5 CCS C Compiler. I used this compiler before at the university as well. The problem is that the CCS C Compiler is neither able to program the PIC18F Microcontroller via ICD3 nor does it execute the debug function. Is ICD3 even supported by CCS C Compiler? Note that I am able to program my microcontroller via the Microchip "Integrated programming environment" but not via CCS C Compiler.

When it comes to programming the microcontroller, ICD3 is not even in the list in the CCS C Compiler GUI. So I use the Microchip software to program the microcontroller. Now when I click on debug in the CCS C Compiler, it says "Select JRE directory". I am not sure what JRE is. Once I select any directory, I get an error message saying "Target could not be detected".

There are then 2 options, either click on "run diagnostics" or click on "ok". If I click on "run diagnostics" the next error message says "The application was unable to start correctly (0x0000142). Click OK to close the application".

Does this mean that I should now abandon the CCS C Compiler and move to MPLAB?


texts:
I created a CAN transmit project for dsPIC33EV32GM104 using MCC plugin. I used the example program given in the can1.h. When i try to debug and check the functionality of CAN bus i am getting struck in the CAN1_transmit function which returns a status called  CAN_TX_MEG_REQUEST_BUFFER_FULL. So i cant able to get any output in my CAN analyzer terminal window. The dsPIC runs at 40MIPS. I am using a CAN bus analyzer from microchip to receive the data from MCP2561 transceiver. CAN bitrate set at 250 Kbps. This is my code
#include "mcc_generated_files/system.h"
#include "mcc_generated_files/can1.h"
#include <stdio.h>
#include <libpic30.h>

int main(void)
{
    CAN_MSG_OBJ msg;
    uint8_t data[8] = {0x41,0x42,0x43,0x44,0x45,0x46,0x47,0x48};
    SYSTEM_Initialize();
    CAN1_TransmitEnable();
    CAN1_ReceiveEnable();
    CAN1_OperationModeSet(CAN_CONFIGURATION_MODE);

    if(CAN_CONFIGURATION_MODE == CAN1_OperationModeGet())
    {
         if(CAN_OP_MODE_REQUEST_SUCCESS == CAN1_OperationModeSet(CAN_NORMAL_2_0_MODE))
         {
                msg.msgId = 0x1FFFF;
                msg.field.frameType = CAN_FRAME_DATA;
                msg.field.idType = CAN_FRAME_EXT;
                msg.field.dlc = CAN_DLC_8;
                msg.data = data;

                while(1)
                {
                     if(CAN1_IsBusOff() == false)
                     {
                         CAN1_Transmit(CAN_PRIORITY_HIGH, &msg);
                         if(CAN1_IsTxErrorWarning() == true)
                         {
                               break;
                         }
                     }
                }

}}}

This is my primary clock setting

This is my CAN module setting

This is the pin setting for CAN

This is the debug info about CAN transmit message status

This is CAN analyzer setting

This is CAN1.c (MCC plugin generated file) uploaded to github
https://github.com/vijayakumar-sargunam/CAN-TX-RX/blob/main/can1.c


texts: LM317-based adj power supply output takes a while to stablize

texts:
I recently built-up a quick little LM317-based adjustable power supply schematic:

However I've noticed the output can take several seconds (on the order of 10 or so) to "settle down" after turning the trimmer to desired output voltage. What happens is if I set it to 5.000V (as an example), my DMM will show the output slowly tick down in 1mV increments or so until the voltage finally settles; sometimes as much as 100mV lower than what I initially set.

Doesn't seem to matter if I turn the trimmer fast or slow. Once I let go, my DMM will show the voltage slowly "tick down" until it finally stabilizes. The same issue occurs with or without load. To provide stable load for testing (100mA or so) I'm using a constant current dummy load similar to the EEVblog one. Also, originally I didn't have the 10uF adj cap, but adding it doesn't seem to make a difference.

Any idea why this is happening or is this just normal? Seems like I have enough smoothing capacitance so I don't think it's a ripple issue. Could it be too much capacitance on the output? I've seen other people demo their LM317 circuits on youtube and their DMM doesn't seem to "tick down" after setting the output voltage like mine does.

Maybe my DMMs are just too accurate, heh. =)

EDIT: I tried replacing the 'dummy load' with a simple 1k resistor (also tried a 100-ohm). Didn't really seem to make a difference. Also, seems like after I set the voltage my meter 'ticks down' pretty fast at first then slower and slower. "Feels" almost logarithmic:

I just remembered my agilent meter does data logging (duh). Here's graph of ~90 data points showing the voltage drop (after setting to around 5.25V or so) over ~90 seconds:

Here's another over 5 minutes (I was trying to dial-in 15V):

UPDATE:
Replaced the 5K pot (which was a crappy single-turn rated at 50mW) with a 5K 10-turn precision pot (rated at 2W). Now I can crank it up to, say 5V or 12V or whatever and my DMM shows a stable reading right away.


texts:
I'm writing requirements for our PCB designs, determining what clients want and what's possible to build. When requirements are finalized, I write tests for the same designs.

Right now, I'm doing it using plain old Word + lots of emailing back and forth. I've tried other solutions like Polarion ALM and Axiom, but found them even harder than Word + email. Is there any simple tool for writing requirements and tests?


texts: Why is this 240V / 20A motor labelled 3HP?

texts:
Here's the motor badge:

As far as I know, 115 V x 40 A = 230 V x 20 A = 4600 watts which is equivalent to ~6.2 HP, all presumably @ full load.
So what does the "3 HP" mean?
I know that in some cases the "marketing HP" is often loosely based on reality but usually that is in the sense of inflating the HP number to exaggerate capability. This obviously doesn't fit that pattern.


texts: Does the Bluetooth protocol inherently support bidirectional data transfer?

texts:
Bluetooth is used for a lot of devices that send data in one direction: keyboards, mice, headphones. If it was designed for that, I would think that it was originally specified to only send data in one direction. Is that true?

Note that I am not talking about sending acknowledgments back to the sender (which is necessary for data transmission). You could have two channels, to support bi-directional exchange, but I am not asking that. There could be later versions of the specification that provide two-way exchange, but I am not asking that either. I am asking: Was the basic Bluetooth protocol itself designed to transmit data in one direction?


texts:
I'm trying to make an Arduino controlled irrigation timer. My idea is to use an Arduino pro mini and a cheap solenoid valve, wired to a TIP120.

However, from my calculations, it's impossible to run it on batteries for long. From what I've seen they draw a considerable amount of power. (the one I'm using is similar to this one https://www.adafruit.com/product/997).
If i power it with 9V, it draws 240mA, which is 2.16W. And if i power it for 30 minutes, it draws 1 watt-hour. That is way too much to use with batteries.

How do battery powered controllers work then? (like this one http://www.ebay.com/itm/Home-Water-Timer-Garden-Irrigation-Timer-Controller-Set-Water-Programs-/231932984347?hash=item3600487c1b:g:HAcAAOSw9ZdXKbTA)


texts:
I was reading a chapter on Step down Choppers(Buck Converters). I had trouble understanding the operation of the circuit as it wasn't explained properly in the book. When I looked up on the internet , I noticed that buck converters had Capacitors in parallel with resistor as the load.

However, the book doesn't mention the capacitor . No capacitors are included in the diagram either. The load is simply a resistor. (I have a crappy camera so can't upload a picture.)How would this circuit operate?


texts: Can I operate TLC5947 24-Channel, 12-Bit PWM LED Driver by just manipulating GPIO pins on Jetson Nano?

texts:
It is often written that Neopixels are not directly controllable by manipulating GPIO pins on  SBCs because the precise timings cannot be met, especially when from user space. I need somehow to drive the TLC5947 that is a full color RGB LED driver taking the following signals:

Data (SIN), a bit to read.
Clock (SCLK), read a bit to display as currently represented by SIN.
Move from shift register to display register (XLAT).

From the description looks like it only matters how do these signals  relate to each other. Hence I could set the SIN bit first, wait for a short time, then set the SCLK clock, wait, remove the SCLK clock, repeat. Even if my delay times vary slightly, should not actually matter as long as I keep the order which signal goes after what. Hence if my C++ program controls all 3 bits as separate GPIO lines (for instance, by writing into /sys/class/gpio/ as described here) I hopefully could get without adding a separate Arduino board and the solving another complex problem how the board should communicate. Is it reasonable to expect this to work? 24 channels is not so many, it it would manage in a couple of seconds, should be ok.
From my search over web it looks there may be other (and likely "cleaner") ways to solve this problem but after two days of googling I have lost myself completely between all kinds of Python, Arduino, Neopixels and RPi. My device is Jetson Nano, my programming language is C++ and I need to drive my specific device. If anybody knows the alternative and better way to solve my problem, this would also be a great answer.
Another question about tlc5947 is here. It is not closely relevant.


texts: How to add a simple ESD protection to RDA5807M FM tuner antenna pin?

texts: I am using an i2c controlled FM tuner IC (RDA5807M) in a DIY fm radio, but I am a little bit worried about ESD protection on the Antenna line (A headphone lead being used for this). Can i add standard 1n4148 diodes for this purpose? There will not be any strong human body ESD because i live in a quite hot and humid country, so just basic protection will do. I want to achieve this using standard parts only and not some specialised TVS diode or fancy ESD protection diodes. I want to know if there will be any signal attenuation due to the stray capacitance of 1n4148 diodes (3pF max, according to datasheet) or its leakage currents. I have attached the relevant part of my circuit diagram. Datasheet of the FM tuner IC - https://cxem.net/tuner/files/tuner84_RDA5807M_datasheet_v1.pdf


texts: Energy is dissipated in the form of heat

texts:
I read in the "Lessons in Electric Circuit" book, volume 2:
"One might wonder why anyone would bother with such a thing as AC. It is true that in some cases AC holds no practical advantage over DC. In applications where electricity is used to dissipate energy in the form of heat, the polarity or direction of current is irrelevant, so long as there is enough voltage and current to the load to produce the desired heat (power dissipation)."

Why is current irrelevant "In applications where electricity is used to dissipate energy in the form of heat"? What's a good example about this?

Regards,


texts: Solving a circuit with a directional loop

texts:
I came up with the following circuit:

Please disregard the labeled values in the diagram - the resistances are identical for the sake of simplicity, and of value \$R\$, and the voltage has value \$V\$. Assume ideal circumstances regarding the diode, wires, etc.

I'm not able to solve it because I can't seem to find the total resistance.

As stated in the diagram, there is a parallel branch which splits into a diode facing against the positive end of the circuit and a resistor, in series with an identical resistance.

In my attempt at solving this, I imagined that once the positive current reaches the bottom node, it splits into current going through the resistor towards the negative terminal and current that re-loops through the resistor that was just passed.

Given that assumption, the circuit acts as a series parallel circuit whose net resistance can be found by
$$
\Sigma R = R + x
$$
where \$x\$ is the value of the resistance in the infinite parallel branches that result from the current re-looping. Then, \$x\$ would seem to be given by
$$
x = (\frac{1}{R} + (\frac{1}{R} + (\frac{1}{R} + ...)^{-1})^{-1})^{-1}
$$
$$
x = (\frac{1}{R} + x)^{-1}
$$
$$
x^2 + x/R - 1 = 0
$$
$$
x = \frac{-1/R + \sqrt{1/R^2+4}}{2}
$$
But this value of \$x\$ isn't even dimensionally correct!

Is there another approach I can use to find the resistance?


texts: Adding activity indicator LED to 3.3V serial line using enhancement mosfet

texts:
I want to make a PCB with a STM32 MCU on it. I will only have a 3.3V supply rail for this PCB. I will be using UART for some communication (AFAIK it is ACTIVE LOW) and I am planning to have activity LEDs for when the UART is doing something.
I will be using highest possible transfer rate (e.g. above 400k baud). Is there a way to add non-intrusive LED indication on these line? I have something like this in mind, but I can not find a actual part for M2 that allows 3.3V as source and <1V as gate.
Please mind that SCM below shwos 5V, but it is meant to be 3.3V

Is this a reliable solution at all? if so, can you recommend me an actual part number?
If not a good solution, what would you suggest?
UPDATE
While searching, I found 74HCT1G125 which is a line buffer with inverted enable pin. Would something like this be feasible?


texts: What is the exact purpose of this 2.2kOhm resistor in the circuit?

texts: My best guess is that it's there to drop the voltage down to 0V by the time the current reaches the negative terminal but I'm not sure if that's the case; and if it is, is it absolutely necessary to be there and why exactly? Also a side question: Why is the voltage dropped to 5V in the beginning of the circuit, wouldn't it work if it remained 9V?


texts: As I know we need larger trace width to handle higher current but some PCB got small PCB trace for signal. Why they don't use large trace if it's no any disadvantage?. Are there any reason or factor for minimizing trace width? (ignore space constrain)


texts: using exit(EXIT_SUCCESS) or exit(EXIT_FAILURE) in AVR or any other microcontroller

texts:
How does one use exit(EXIT_SUCCESS) or exit(EXIT_FAILURE) in microcontroller C programming. I  know it works on application level C programs when you include #include<stdlib.h>.

The idea is to exit the main loop altogether when some unexpected value is returned, for example.
What exactly would be the common approach in such a case? I could do a Reset but i want to see if somethings gone wrong in main. Is it a good practice to use goto: exit_main or something similar?


texts: Can I connect a 16 ohm output signal to a line input if I use a resistor in series?

texts:
newbie here.

I have a Hi-Fi system and I wish to connect its output to a line input in another system while still being able to hear through the Hi-Fi´s original speakers.

If I use the Headphone jack, the speakers will be muted, but my sistem has an extra output meant for "surround" speakers. It specifies that this output is for 16 ohm speakers.

My question is: If I wanted to use this output as a "line  level", would it sufice to use resistors in series to rise the impedance to around 47KOhm? or is there a more efficient way of converting this low impedance output to line level?

I should add that I do not wish to tap the audio output from the integrated circuit as this is for the moment beyond my ability as I am a complete noob in electronics (but I do not discard the possibility of doing this in the future).


texts: Equivalent noise resistance(s) - 2 stage amplifier

texts:
I came across this question in my textbook:

  The first stage of a 2-stage amplifier has a voltage gain of \$150\$,
  an input resistance of \$1500 \Omega\$, an equivalent noise resistance
  of \$700 \Omega\$ and an output resistance of \$20 k\Omega\$. For the
  second stage, these values are \$500\$, \$50 k\Omega\$, \$1200
 \Omega\$, and \$1 M\Omega\$ respectively.

  Sketch the circuit diagram illustrating this scenario
  Calculate the equivalent noise resistance of this 2-stage amplifier

I'm having a bit of a confusion regarding this question. Shouldn't the output resistance of the first stage be same as the input resistance of the second stage of the amplifier i.e. \$R_2\$?


texts: What is the charging current specification of a BMS?

texts:
I'm planning on using this BMS: https://www.aliexpress.com/item/3S-11-1V-25A-Li-ion-Lithium-18650-BMS-PCM-battery-protection-board-bms-pcm-with/32816991614.html

And 3 Samsung 18650 cells in series: http://dalincom.ru/datasheet/SAMSUNG%20INR18650-25R.pdf

In the datasheet of the cells it says that "Charging current shall be less than maximum charge current specified in the product
specification". I suppose that maximum charge current is 4A since that is the Rapid charge current as mentioned in the datasheet.

The BMS doesn't give any specification for its typical charging current. So how do I know if it exceeds the 4A?

Also the input voltage range of the BMS is not given. Of course it is at least 12.6V but what is the maximum? Can I hook up a laptop charger?


texts:
I am working on a basic PIC based circuit to improve myself. What I want to do is to make LED's on one by one, every time I press the push button. I am using external interrupt to do this.However, I am in trouble with the push button which I use at RB0. INT0 external interrupt should occur every time I push the button but it never happens. But I am not sure about it. It might be caused by something else. I will be glad if anyone helps me to solve it. Circuit and codes are below.

#include "newheader.h"
#include <pic18f2550.h>
#define _XTAL_FREQ 4000000

int intCount = 0;

void main(void) {
TRISB = 0x01;
TRISC = 0x00;

INTCONbits.PEIE = 1;
INTCONbits.INT0IF=0;
INTCONbits.INT0IE = 1;
INTCONbits.GIE = 1;
INTCON2bits.INTEDG0 = 1;
INTCON2bits.NOT_RBPU = 0;
while(1);

}

void __interrupt() isr(void){
if(INTCONbits.INT0IF==1){
    INTCONbits.GIE = 0;
    __delay_ms (50);
    if (LATBbits.LB0 && intCount == 0){
        __delay_ms (50);
        PORTCbits.RC7 = 1 ;
    }
    if (LATBbits.LB0 && intCount == 1){
        __delay_ms (50);
        PORTCbits.RC6 = 1 ;
    }
    if (LATBbits.LB0 && intCount == 2){
        __delay_ms (50);
        PORTCbits.RC2 = 1 ;
    }
    if (LATBbits.LB0 && intCount == 3){
        __delay_ms (50);
        PORTCbits.RC1 = 1 ;
    }
    if (LATBbits.LB0 && intCount == 4){
        __delay_ms (50);
        PORTCbits.RC0 = 1 ;
    }
    if (LATBbits.LB0 && intCount == 5){
        __delay_ms (50);
        PORTC = 0x00 ;
        intCount = 0;
    }
    INTCONbits.INT0IF=0;
}
intCount++;
}


texts: I've read a lot of post saying that TIs XDS100v2 JTAG emulator is not supported by OpenOCD. However, looking at this link, I see that the XDS100v2 is a supported FTDI chip. So I'm kind of confused on if it is or not. I do have a license for Code Composer Studio but It may not always be available so I would like to have a backup plan.


texts: How does a dead battery look in a circuit?

texts:
I'm working on a Kirchhoff's problem where two car batteries are connected in parallel.  One is dead and one is good.  It's a basic three variable problem where I'm working out the three different currents (I1/I2/I3) in the circuit when the switch is closed.

My question is how do I treat the dead battery in the circuit?  I would have thought that being dead you would make the voltage equal 0 Volts because it has no potential for current but my instructor is calculating using it at 12 Volts.  Is that correct and if so why?

simulate this circuit – Schematic created using CircuitLab


texts: Can someone please help me with this pipelining question

texts:
A pipelined implementation of the circuit shown below is to be designed. The delays of the building
blocks are indicated inside circles. You are given buffers with a delay of 0.5 ns, and flip-flops with hold
time of 1 ns, setup time of 2.5 ns, and clock-to-Q delay of 2 ns. There is also a clock skew of 0.25 ns
per flip-flop going from input (left) to output (right). What is the minimum clock period (in ns) for which
the circuit will work.

The answer given by my instructor to this question is 8.25ns.

If the pipeplining is done such that a flipflop is placed before and after 4ns delay element, then the min. time counts to 4(t comb)+2.5 (t setup)+ 2(t clk-Q) -0.25 (t skew, l to r) =8.25.
This was the way that I came up to the given answer so as to ensure min time by pipelining. But what I can't understand is whether my approach is correct or not!


texts: Encoder to Arduino connection (22A ERCB)

texts:
I have the following encoder below that I would like to connect to an Arduino.

I am trying to figure out how to connect the 3 wires.  The 2 grey wires I assume are the signal pins as usual and should be connected to interrupt pins on the arduino? (correct me if I'm wrong) but I'm not sure where to connect the red wire.  Most tutorial I read tells me to connect it to GND but on the data sheet it says

Analog output - Current / voltage and PWM output

Datasheet:
http://www.rotacol.info/22aercb.pdf


texts: How can I remove transformer windings from wooden template?

texts: I usually wind my larger MOT transformers by using a 2x4 as a template, then I push the zip-tied winding off the 2x4 and into the E section of transformer. As I knew I would be fighting for the last turn on this specific winding, I REALLY wound it tight. I cannot get it off. I've tried slowly punching down each side with a hammer and wood buffer. I've lubed it up with some olive oil. I've got a big clamp holding the "buldge" (mine doesn't really have one since it's so tight). I REALLY do not want to have to rewind this one. I'm sure I can come up with a primitive violent way to get it off, but I would love to hear from someone with a clever idea or has been in this frustrating situation before. Thanks. Picture attached


texts: LSM303CTR 3-wire SPI and I2C - conceptual problem

texts:
I'm trying to interface LSM303CTR e-compass from ST-microelectronics with microcontroler. Due to design limitations I have to use 4-wire SPI.

This MEMS device has option to switch beetween 3-wire SPI/I2C by using ChipSelect pin (which I personally think is an absurd).

When CS is low - SPI is active, I2C is endisabled and chip is selected
When CS is high - SPI is disabled, but I2C is enable

Here lies the problem.
It I unselected chip by pulling CS high, I also enable I2C transceiver in MEMS device. But my MEMS sensor is connected to same bus with other devices.
I have other devices on same bus (SD memory, LCD). I don't want to interfere with transmission from SD and LCD.

So here are my questions:

How to safely interface 3-wire SPI with 4-wire SPI
How mentioned I2C transceiver in MEMS device could interfere with my SPI bus while CS is high-state.


texts: TPS61046 wrong output voltage and high current consumption

texts:
I am designing a circuit to control a multiplexed led matrix and for that I am testing two boost circuits. The TPS61046 and the TPS61080.
My idea is that the input voltage is via USB or a Li+ coin cell (probably Li-ion@3.7V).
The attached schematic shows the power supply stage, the ground is common between both boosts but only one is energized at a time and the other is kept disconnected. (possible first error)

Since my priority is to run the TPS61040 due to its size and better performance in the current range I require (10 - 30 mA) I will focus this question to the error I get from it.
When I test its operation supplying it with a laboratory power supply set to 3.7V max 0.1A I get the consumption of 2.4V@0.097A, that is, the TPS61046 is consuming -IMO- an excessive amount of current. I must say that the loads so far have been three leds in parallel, each with a 400 ohms resistor and the other was an Arduino mega. I havent conected the whole circuit due to potential smoke risk.
In the attached picture you can see the PCB layout I made, R10 and R20 are not connected and R21 is a 0Ohm 1/4W resistance, this way FB with Vin ar directly connected, thus 12V can be obtained only with 3 components C_in(C6&C7)= 2x1uF, L(L2)= 10uH, C_out(C5)= 10uF (Datasheet 9.3.1).

Something that can cause another failure (possible second error) is the distance of C_out (C5), which maybe should be closer to Vout, but even so, I think the effect should be reflected in the ripple and not in the difference of the voltage I get to the desired one.
I have checked the continuity between all the pins and the TPS is well soldered. GND-Vin diode shows 0.5V (possible third error). I will also do a re-work on the inductor to be sure there is no short underneath.
Wrap up: Using the TPS61046 I want to get 12V output but I am getting a lower value with a very high current consumption.

SOLUTION: IC wasn't able to start up. By increasing the current limit a little it worked flawlessly.
Thanks, @Andy aka


texts: How to remove these lines in Altium Design

texts:
In my design, there are some lines with "=" on them. Can someone tell me why these lines appear and how to delete them? I'm using Altium18.

Thank you.


texts: Can I use a back to back Zener as a flyback diode for an AC coil?

texts:
I am using the below AC electromagnet to switch on/off a pneumatic system. (It is a pneumatic actuator. I think that is what it is called.)
The issue is, when I turn off (disconnect the switch) the coil generates a big negative voltage spike in my nearby PCB electronics and cables and messes up with my LCD screen and buttons (they get randomly pushed.)
Except for having to remake my PCB to be EMI-proofed, which is costly, can I use two Zener diodes back to back to create a 'fly-back diode' for the AC current?
What other techniques there are?
Pneumatic actuator:

The initial schematic:

simulate this circuit – Schematic created using CircuitLab
The one I am thinking of implementing:

simulate this circuit


texts: Why OpAmp is designed to have a cut-off frequency 1 kHz, but indicated Op Amp respond to sinusoidal input of 10 kHz?

texts: An Op Amp is designed to have a cut-off frequency about 1 kHz, a circuit designed  with  the  indicated  Op  Amp  is  able  to  respond  to  a  sinusoidal  input  voltage  at 10 kHz. How is this possible?


texts:
I'm writing to make sure my process is correct in this design.
I'm going for a standard 4 layer board with layers 1 and 16 as signal layers, and layers 2 and 15 as VCC and GND layers respectively. I have filled layers 2 and 15 with the necessary polygons and names them to match the schematic. My only question really deals with the design of the layers and the use of vias (see picture). Is this the best way to accomplish my goal here? I am dealing with a relatively dense circuit as size needs to be kept down (insect cybernetics). Could I get some second opinions? This seems to be the best design.[

I want to be able to connect to the vcc and groun planes from the top level only. This setup has allowed me to select the layer combinations I was looking for with my vias.

Thanks everyone.

EDIT/UPDATE

After reading what ThePhoton says I tried a new approach by eliminating the blind vias and instead using a more conventional 4 layer board setup.

And for via settings I simply renamed its net. Will this give me the desired effect?


texts: Reducing errors in 3-wire PT100 RTD measurement using a Keysight 34461A DMM

texts:
I have a 3-wire PT100 RTD with 1.5 m long cables, which I want to measure with a Keysight 34461A DMM. This DMM has a temperature measurement mode for use with RTDs. Aside from bundled probes, I have these Kelvin-type probes.
I'd like to reduce measurement errors, within reason. Here is a procedure that I came up with:

Connect each Kelvin probe to a different red wire
Switch DMM to 4-wire resistance mode
Note resistance between red wires (about 0.26 Ω in my setup)
Remove one Kelvin probe from one of the red wires and connect to the white wire
Switch DMM to 4-wire RTD temperature mode
Add resistance measured in step 3 to R0 of 100.000 Ω (therefore 100.260 Ω using the example measurement from step 3)

I'm assuming the resistance measurement of step 3, between both red wires, is a good approximation to the resistance of the white wire plus one red wire.
Also, I believe the offset adjustment of R0 in step 6 is reasonable; although RTDs are not perfectly linear, the adjustment is on the order of 1/400 of the nominal 100 Ω value, so non-linearity errors should be negligible.
I'm looking for validation of the procedures used, as well as suggestions for improvement. For reference, using this procedure to measure a ice/water bath, I got readings within a few mºC of 0 ºC, whereas without any offset adjustment, I get about 0.6 ºC.


texts:
JTAG, SWD, EDBG, ICSP, ISP .

Can someone simply explain their differences.

For example if EDBG debugger can ALSO program flash, why Arduino boards have both ISP and EDBG ?

http://www.armlearning.com/wp-content/uploads/2017/10/4c10034e18f9380ff03a140a4835faff.jpg

And in picture, why they wrote "SWD(EDBG)" ?

Whats the point of writing EDBG and writing it in paranthesis ?

Why ISP and ICSP have the same meaning ? Why not only one abbreviation ?

And finally, what is the relationship of JTAG with all this ?


texts: Have I routed this PCB correctly per the schematic

texts:
This is my first PCB for production, and I'm not sure if I've correctly routed it.  Mostly I'm concerned about trace running from pin 5 of IC1 to C3/C4 and how that picks up the +5V, which I've routed going anti-clockwise from the bottom of the board. Should I leave it there (between C3 and C2) or should I move it to the left (between R1 and C4) or does it make a difference?

edit

so based on the comments I had a few problems.  I've fixed the mixed up pins on the MOSFET, shortened/fattend the traces, and routed a few things across the back layer and added the ground plane there. I've kept the curved traces, because I'm a freak and I don't care :) Original question still in mind, does the PCB match the schematic?:


texts: MOSFET not fully OFF when Gate Voltage is 0V

texts:
A N-channel MOSFET STP16NF06L is used to drive a 12V load.

Pin 1 is connected to Arduino Uno digital pin 4.

Pin 2 is connected to the negative terminal of the 12V load.

Pin 3 is connected to the GND terminal of a 12VDC power supply.

The positive terminal of the 12V load is connected to the +12V terminal of the 12VDC power supply.

Problem: When the Arduino output pin is at LOW state and measured to be at 0V, the MOSFET still turns on and passes 6V to the 12V load.

When the output pin is in the HIGH state, it's measured to be at 4.9V and 7.5V across the 12V load.

Shouldnt the MOSFET provide 0V across the load when pin 1 is 0V, and just above 10V when pin 1 is at 5V?

Pin 1: Green clip to Arduino pin

Pin 2: White clip to negative terminal of load

Pin 3: Black clip to GND of 12V power supply


texts: Best way to build a 64-bit output multiplexer

texts:
I'm looking to create something to multiplex N 64 bit signals together. The goal of the project is to provide digital switching between a library of old cartridge based video games.

Essentially I want to have a number of cartridges always 'hooked up', but only one set of lines connected to the console. I could do it with 64 single output multiplexers but its seems like I'm going about it the wrong way. Any suggestions on ways to simplify the design?

P.S. - I've been thinking about this a little more, and I have an idea for an alternative approach but I'm not quite sure how to execute it. I don't really need to quickly switch between the 64 bit inputs with any sort of speed, which is what a multiplexer would support. All I really need to do is to tie a given cartridge to the console, while electrically isolating all of the other cartridges. For that, I would essentially need 64 relays for each cartridge. I'd like to avoid that, so I wonder if there are any sort of on/off pass-through chips or circuits I could construct. All I would need is something with 64 ins/outs, +1 to open or close the 64 switches. Ever heard of anything like that?