texts:
I am confused about the operation of solar cell. Maybe its because i still did not quite understand the effect about the voltage drop across a solid state device. We operate in quadrant 4 where current is negative while the voltage is positive and hence they point in the same direction so acting like a battery.I understand how current is being generated because of optical generation but i dont quite understand the voltage being generated by the solar cell. Please give an intuitive answer.
-Thankyou


texts:
I am given a question relating to a bipolar junction transistor. The information I am given in the question is shown below.

I am first asked to select a quiescent point from the graph to find \$V_{ceq}\$ and \$I_{cq}\$ which I did by choosing the midpoint of the load line giving \$V_{ceq}=10V\$ and \$I_{cq}=12mA\$. I am then asked to find \$I_{bq}\$ using the information I have just calculated and the information from the question.

I am assuming I use the equation \$I_{bq}=\cfrac{I_{cq}}{\beta}\$ but I am unsure of how I work out what \$\beta\$ is without being told it in the question. Or is there another equation I can use to calculate \$I_{bq}\$?


texts: How do I reduce the number of GPIO pins used for a CMOS camera?

texts: I'm gonna make a cheap 360 camera with 5 of these OV7670 cameras but they use a whopping 18 GPIO pins each! (Btw, 18 X 5 = 90 Pins!) I'm using a C.H.I.P computer to control all this mess, but even then, it only has 80 GPIO pins! I've seen a camera that only uses four pins and the only reason I'm buying this is because it's dirt cheap. Is there any way to shorten the amount of pins this camera uses?


texts: Programming a Baby Orangutan using Arduino Uno?

texts:
I have the following setup:
Arduino UNO without the chip:

Notice that the Atmel chip is missing.

And i have a Baby Orangutan:

The orangutan burned with Arduino Uno R3 Bootloader.

I connected Orangutans PD0 (RX) and PD1 (TX) to the Uno's D0 (RX) and D1 (TX) so that i can program the orangutan using Arduino AVR programmer.

When I'm connecting my Uno to the PC using a USB Cable, it's being recognized as a Uno R3 even when the chip is off, becuase the Orangutan has a Uno bootloader.

Now the problem is when I'm trying to upload a sketch it sais:

avrdude: stk500_getsync(): not in sync: resp=0x00

UPDATE:

The following pins are connected:

> Uno      -->   Orangutan
> D1 (TX)  -->   PD1 (TX)
> D0 (RX)  -->   PD0 (RX)
> 5V       -->   VIN
> GND      -->   GND
> RST      -->   PC6 (RST)

Following: Baby Orangutan B Pin Mappings.


texts: Amplifier circuit with clamping output signal

texts:
Hello. I am currently studying transistors and working on a Common Emitter amplifier for our project. We are asked to create our own power supply circuit and use it to power our own amplifier circuit. My output signal is clamping as shown in picture 2 and I don't know how optimize it so that it will have an output similar to the first picture. The first picture is the one connected to a 9V DC component, while the second one is connected to the AC-DC converter power supply. Any explanations on this?

*Edit: We are only required to simulate our circuits. I am currently using LTSpice to simulate the circuit.


texts: Why does the current rise and fall linearly in a DC-DC converter?

texts:
I don't understand why the current in a DC-DC converter rises and falls in a triangular waveform pattern. I think it has something to do with the energy in the magnetic field, but I don't know any equation to back this up.

When the switch turns on and off, the through the inductor changes in a square waveform between the current through the load and current through the switch. Therefore, where does the linearity come from, as shown in graphs like below?


texts:
I am trying to design an audio amplifier circuit using BJT
These are the requirements of the circuit
Input signal: 50-100 mV (It's the output of my iphone's mic)
2W-4ohm speaker
There is no requirement for DC voltage source. I can choose so as to feed enough for my circuit.
Here's my approach

I choose to use 12V DC source and design my circuit into two blocks. The first block is an EC amplifier stage which is to amplify my voltage according to the requirement. The second block is for power amplifier, in which I choose emitter-follower  as driver stages before a push-pull circuit. I want to use class A stages in that position for impedance matching and to increase the total gain of the power amplifier

But the problem is my power amplifier stage doesn't seem to work and the output of the first stage is just 2V peak (It is expected to be 4V peak)

Is my design reasonable? If yes, what's wrong with it?


texts: driving a synchronous motor as a generator

texts:
Say I have a 100 kW synchronous motor in a building driving a pump/fan etc as part of an HVAC system.

1 - if I drive the shaft of the motor at 100 KW (from somewhere else), then the load on the motor will be zero and the motor will take no energy (to 1st order)?

2 - if I drive the shaft of the motor at 200 kW then it acts as a 100KW generator? This is what I understand from synchronous motors.  If my electrical demand on that circuit is 100kW (from other things) then is my electricity drawn from the grid zero?

3 - If I have 100 kW other demand on this subsystem, and drive the synch motor shaft at 300kW (from elsewhere) then I have a 100kW 'extra' - does this get 'exported' to the grid?  Am I missing something?

Thanks in advance

Russ


texts: How to isolate a zero-cross detector from phase-controlled simistor?

texts:
To control the average voltage, output by a triac, the controller needs to know the time of the zero crossing. But the circuit for detecting the zero-crossing is a sensor, vulnerable to noise; taking it's input from the mains - same place the thyristor is injecting noise into.

What are some general guidelines for designing a system of 1 zero-cross detector, one micro-controller and several phase-controlled triacs of about 900W each?


texts:
I am currently looking at this battery: http://www.ebay.com/itm/DC-12V-1800mAh-Super-Rechargeable-Pack-Protable-Li-ion-Battery-EU-Plug-For-CCTV-/400940782911?hash=item5d59eed53f:g:mxwAAOSw5dNWj4Bn

I am going to use it for a slightly large robotics project where 12v is required for several sensors, 4 motors (2 in each output of an l298) and an arduino mega. Since the battery only has a male and femal dc jack (no  regular wires) am I able to use this for the male jack to go into so I can plug into a breadboard?

I have used nimh batteries for my last project and the charge of them vary over time and from looking at many different lithium battery packs ive seen that some of them drop charge quite a lot, Is this true for all of them? The reason i am looking at li-ion is because from googling it seems the best choice out of nimh and li-po (cheaper and safer). Would you suggest this a good choice of power supply? (im on a tight budget too)


texts: How to design a switched mode battery discharger

texts:
I have a very basic understanding of switched mode power supplies and know that this is a simple buck converter suitable to e.g. charge a 12 V car battery from an input of, say, 24 V, with a dc current that may have some ripple:

The voltage on the battery resp. the charging current can be controlled with the duty cycle on the switch.

My problem is to find a similar schematic for discharging the battery with a controlled current. The purpose is to measure the discharge process in order to find the capacity of the battery. This is a schematic with the disadvantage that the discharge current goes on and off, instead of having just a little ripple:

All I find on the Internet are schematics that regulate the output voltage / current over the resistor, but in my project I need to regulate the current in the battery instead, and want a dc current with just a little ripple.

Any ideas?


texts: What's an easy approach to provide Wi-Fi/Webserver to mobile phone apps without hotspot

texts:
I'm a software programmer and I'm up to start a project of an embedded outdoor device which I will be able to control by any mobile phone.

My preferred approach is having the embedded device provide a HTTP webserver via Wi-Fi, so I wouldn't be required to create different apps for different phones.

What's the most easy way to add such Wi-Fi/HTTP support to a microcontroller? I guess the embedded device will have to provide a hotspot by itself so the phone can connect to it. But I'm not sure about this. Perhaps there are more easy ways?

Bluetooth doesn't seem appropriate here because of its limited reach.


texts: LTSpice print schematic to PDF with command line

texts:
I'm working with an LTSpice schematic that I have formatted to print nicely to a PDF.
Does anyone know of a way to do do this printing using the command line instead of needing to open the schematic with LTSpice and print it manually?


texts: Drive Bistable Single Coil Relay with two MOSFETS

texts:
I am currently in the middle of the a project where I need to drive a relay.
Scavenging the parts I have around I have 2 STP55NF06L logic MOSFETs and a TE Connectivity PE014F12 Relay.

I wanted to drive this relay using an arduino, and while I have found some schematics online, none show how to drive this relay with 2 mosfets, as it is only a single coil relay.

Does anybody know a simple way to achieve this ? i have pleanty of passive components around, I just would rather avoid having to order a dual coil relay if possible.

Any help with a possible schematic for this would be much appreciated.

Cheers.


texts: How is a 50Ω "back-termination" accomplished on a scope probe line?

texts:
I've just been watching Jim Williams' very excellent video on Measuring Switching Regulator Noise. At 1:58 Jim mentions a "50Ω back termination" in the probe setup that looks something like this (but not optional as it is in Linear app note AN-104 from which this diagram is taken):

It is a series 50 ohms, not parallel as at the scope connection, and as I understand it, its role is to absorb any reflections that might travel back from the scope.

My question is: "How is a 50Ω back termination typically accomplished in a scope probe line?"

I kind of suppose there's a through-termination that looks roughly like the common parallel ones, but instead of 50Ω between the center connection and ground, it is 50Ω between the center connection on either side. But I'll be darned if I can find such a thing on search.

Am I not using the right search term ("50 ohm series OR back termination oscilloscope"), or does such a thing not exist as I imagine and folks just solder a 50Ω resistor at the end of a piece of coax or something? :)


texts: How to connect battery and solar panel in parallel to power load?

texts:
Is this [dead link removed] correct?

Think of it as a power bank. The 10 V input is a solar panel.

How is the battery and solar panel connected?

The site say that when the switch is open, solar panel charges the battery. When the switch is closed, does the solar panel and battery together power the load? Is it in parallel?


texts: Can be fuses be replaced by PPTCs as the main overcurrent protection for AC Power Supplies inputs?

texts:
I'm thinking about replacing input fuses for switch-mode and linear power supplies by PPTCs.

PPTCs are more desirable because it's ability to recover itself after being tripped by overcurrent.

There are some high voltages (up to 250VAC) PPTCs out there: Mouser listing for high voltage PPTCs.

Can I do that? Are there any shortcomings in doing that?


texts: LT Spice crossover filter simulation problems

texts:
I'm trying to create a simulation of a speaker system with woofer, tweeter, and midrange speakers.

The total Vout (output voltage of woofer+output voltage of tweeter+output voltage of midrange) should be 0dB in the passband and -6dB at the crossover frequencies (100Hz and 2500Hz).

Why is my total output graph showing it dip down to -40db at the cross over frequencies?


texts:
I got this on an interview question and I still don't know the answer.

  What output will have a nonlinear device if we will give two random frequencies \$f_1\$ and \$f_2\$?

I answered that it will have two carriers but I really unsure about my answer.


texts: In this timing diagram, why am I not including tcpq, i.e. the latch clock to Q propagation delay?


texts: Writing data to external Flash Memory chip

texts:
I develop a microcontroller project that requires writing big chunks of data in a Micron 4Gb SPI NAND Flash memory and I am a little confused regarding manipulation of the Flash memory blocks.

According to the datasheet  one memory die of the specific Flash memory is organized in two planes. The Plane of even-numbered blocks and the Plane of odd-numbered blocks.

And my question is this: in order to write data continuously in the flash memory, do I have to fill with data the even-numbered blocks first(i.e. 0,2,4...2046) and then jump to odd-numbered blocks (i.e. 1,3,5,7...2047) OR is it possible for me to write data first in block 0 then in block 1 then in block 2, etc?


texts: Graph of the output Vo for a given Vi in a diode circuit explanation

texts:
We have the following diode circuit:

We have found when the diode is on and off.

I perfectly understand this.

Now the teacher gave an extra question that I don't understand. What is the output Vo (represented in a graph) when we have an input of

a) \$V_i = 100 sin(wt)\$

b) \$V_i = 150 sin(wt)\$

She then drew the correct graphs. I have attached them here, respectively a and b:

I see the graphs, but I don't understand them. What is their explanation, how are they working?


texts: Stand alone LCD display for sensor monitoring

texts:
I am looking for a standalone (meaning self contained, enclosed, mountable to a wall etc) LCD display to monitor a process sensor. I would like to feed this unit a 4-20mA or 0-10VDC signal and have it display a number (4 characters max) corresponding to a scale I program.

Does anyone have a product or supplier suggestion?

I would like to purchase something off the shelf as opposed to building it, as time is a bit of an issue.

The sensor is a gas detector, which feeds into my monitoring system already. However my client wants a digital display in the area being protected. The display would read 0 to 1000 (ppm)


texts: Solving Unkonw R1 and R2 in classic descrete BJT bais arangment

texts:
im stuck solving the RB1 RB2 values is a classic discrete BJT circuit bias arrangement. Im sure its a simple thing that im just not seeing.

Circuit values given are
Ie=1.5mA
V collector to emmiter =5v
Vcc=10v
beta=100
Re=1k
VA=200V
VBE=0.7
VT=25mV

find
Rc, RB1, RB2.

To start with to simplify things i have ignored VT and VA.
I can determine Rth=(R2.R1)/R1+R2=R1||R2
     and Vth=(R2.Vcc)/(R1+R2) = R2.10/(R1+R2). i can determine Ic=(100/101)(Ie)=1.49mA and Ib=Ith=1.49mA/100=0.0149mA or 0.001mA depending if i use KCL or ib=Ic/beta.

simulate this circuit – Schematic created using CircuitLab
Now i apply KCL from ground through Vth, Rth,and out at base voltage = 2.2. and i end up with a ratios R1/R2=(7.8-IbR1)/2.2=(7.8-0.0149mAR1)/2.2.

From here i am stuck be cause i have 2 unknowns R1 and R2 and don't know any other equations i can apply to solve a value? I have also done a KCL at the RB1 RB2 BASE node and i end up with the same ratio. and i cannot substitute the KCL into the KVL because i end up with 0=0.

Suggestions?

Also what i have learned from making the KVL KVL subsitution mistake is that you cannot substitute KVLs into other KVLs and KCLs because you end up with 0=0. is this always the case?

Thanks


texts: How do I (optimally) connect Elk-924 (high sensitivity relay board ) to DSC PGM output (sinks to ground)

texts:
This sounds like a very specific question, but I think it boils to a generic one -- not at all specific to this equipment.  But it will take a bit of backstory to get there.

My background, btw, is software.  Electronics is a new and recent hobby.

First the equipment:

http://www.elkproducts.com/product-catalog/elk-924-sensitive-relay

(Apologies, can't add picture due to insufficient reputation... you'll have to see the PDF.)

This relay board is powered by 12v and is triggered by what they call a 'highly sensitive' input trigger (T- and T+) that requires very little amperage.

• Operating Voltage:12 or 24 Volts D.C.
• Trigger Current: 1.2 mA @ 12 Volts D.C.
• Trigger Voltage: 5 to 24 Volts D.C.

The second is a DSC PC1864 board.  This board has an AUX (12v) output along with several "PGM" outputs that basically sinks the terminal to ground under certain programmable conditions.

My primary goal is to close the relay under a certain PGM condition.  My secondary goal is to power the relay through the same power source that I'm switching.  Why?  The DSC board has limited AUX power capacity and there's no reason to power the relay from the board if I don't have to.   60ma is almost 10% of the AUX's capacity, and there are other devices already on there.

The power source I am switching is to a camera, so let's call that CAM.  It has its own 12v power transformer, not at all associated with the DSC board.

So this is what I did:

I connected the Elk's POS/NEG terminals to CAM +/-.  I also connected CAM + (and camera) to the relays, the camera directly to CAM -.

I then connected the T- terminal to the DSC's PGM terminal.  I found the camera stayed on all the time, measured voltages, and quickly realized -- OH -- I'm dealing with relative voltages.  The T- isn't isolated from the POS/NEG source.  Negative on each board has relative voltages, of course, and not a common ground.  (right?)

So I connected the DSC's AUX +/- to the Elk's POS/NEG, and T- to the PGM terminal, and it works perfectly.

Question:

If I still wanted to achieve my secondary goal of not powering the relay from the DSC panel, and only connecting the trigger (T-) to the DSC panel -- how could I accomplish this with minimal fuss?  (I mean, obviously I could get another smaller relay powered by DSC's AUX+/PGM-, which closes CAM+/T-, but that's silly.)  Is this a job for an opto-isolator?

And how do I properly size the component?

Thank you!


texts:
I'm currently working on a project where something as silly as a i2c to i2c bridge would be perfect. Unfortunately they don't seem to exist. Anyone know of one? Is there any reason why they don't exist besides no one sees the need?

Let me explain the project. I'm making a module Video switch that can have modules for different input types (RGB, Component, HDMI, etc). Each module will stack with a Microcontroller module being able to control everything in the stack. It would be nice if I would only have to use 2 lines in the board interconnects to control all the boards (i2c). The issue is multiple of the same board can be used in the stack so there would be identical i2c chips on the same bus. Sure I could use DIP switches for each IC to address each on but that make design and software development a nightmare. So it would be nice if I could address a i2c slave on each board (1 DIP switch for each board) and then command that slave to be the master of a i2c chips on that board.

One thought is to use a i2c to SPI connected to a SPI to i2c (Not sure if that would work). Any thoughts on all this rambling? Thank you all in advance.


texts: Solar cell electrical model from datasheet

texts:
I would like to build an electrical model for a solar cell based on its datasheet specifications. As an example, I retrieved one from Digi-Key:
http://ixapps.ixys.com/DataSheet/SLMD480H12L-DATA-SHEET.pdf
So the manufacturer gives Voc, Isc, maximum power point voltages, currents, power, etc. It also presents efficiency, fill factor and voltage variation with temperature.
The general electrical model for a solar cell is the following:

simulate this circuit – Schematic created using CircuitLab

I have searched some sources, and I have found the way SimElectronics from MathWorks does:
http://www.mathworks.com/help/physmod/elec/ref/solarcell.html
In the simplest mode (5 parameters), it uses Voc and Isc from the datasheet, considers Rsh as an open circuit, ignores the second diode, and requires an estimate of Rs and n (diode quality factor). I am not interested in the solar irradiance for the moment, so it will be ignored.

The general equation fo the circuit is the following:

I will follow SimElectronics methodology and ignore Rsh. The parameters I want to retrieve from the cell are Iph and Is. The quality factor will be considered as 1.5 (usual value for silicon diodes) and kT/q as 25mV in ambient temperature.

I have also found that Rs can be estimated from the area of the cell, about 5 ohms for the datasheet cell, which seems reasonable:
http://www.pveducation.org/pvcdrom/solar-cell-operation/series-resistance

Applying Voc = 7.56V and Isc = 20mA (solar cell datasheet):

Solving the equations, I get Is = 5.59e-90A and Iph = 20mA. That seems a little bit strange to me, because the Is is so low it means the diode is basically useless in the model. And the Iph so close to Isc shows no current losses are present in the solar cell. What am I doing wrong?


texts: What are all the tiny features on this microchip?

texts:
I've been reading some very basic introductory material on computer hardware and it occurred to me that I would like to take a look at a microchip to see the physical implementation of a simple logic circuit. I found the following image of a 74AHC00 TTL chip, which I understand implements 4 independent NAND gates. I was astonished at how complex the chip appears to be.

(image source zeptobars.com)

The functional diagram of this chip is below, and I think I can see the 4 NAND gates in the die shot as 4 repeated patterns in the centre. Each appears to be composed of hundreds of fine structures. My novice understanding was that NAND gates could be constructed from only 4 transistors, which I thought were elementary components. Clearly my expectations are flawed and I have a lot to learn. So can anyone explain what I am looking at in this image?

(image source NXP datasheet)


texts: Won't 0.1 ohm resistor's leads add resistance to its value?

texts: Normally we neglect the resistance added by the leads of a resistor because it's too low compared to the resistor's resistance value. But can't this be an issue when it comes to a very low resistance like 0.1 ohm (like the one in the photo)or even less?


texts: Do I have to follow specifications strictly when using AC?

texts:
I have some device with a connection terminal which can deal with (quote)

max. 1 A/24 Vac/dc.

I would like to use it for switching a device with 1A and 12V AC. How are the specifications meant? Is the peak value (since it says max) or the RMS current/voltage meant? Since 1A AC will exceed 1A at the peaks I am afraid to break my device if I tried.

EDIT

The device is a Rocom Doormaster Smart 4+n. On that page it says "Max. load for driver contacts 3 to 5: 24 Vac/dc 1 A" which I am afraid to exceed with my 1A AC at the peaks.


texts: How and what kind of noise can an optoisolator filter?

texts:
How does an optocoupler filter noise?

As an illustrative example, below three remote sensors are receiving pulses from a single source:

In the top scheme there is no optocoupler/optoisolator. In the second scheme there is an optocoupler(colored in green) right before each sensor.

And i actually tested this. I first connected the source pulse train to a 100m coaxial cable and at the end of the cable I hooked it up to an oscilloscope. I didn't perform noise analysis but the first thing I noticed was there random was ringing twice the pulse amplitude seen on the scope.

Then I used an optocoupler an the ringing completely disappeared.

This made me believe that the optoisolator really works good for long distances.

One thing I can see that it separates the ground of the source and the receiver. But that would I guess only take care of the 60/50Hz ground loop noise.

How is an optocoupler/isolator filtering the noise? How can we understand the logic behind?


texts:
I am using a ready board (using AD620) in my circuit as a current monitor.I have set the gain of the board to 10x.

1)My first question,is this a right way to approach the problem.My trials show that it is working with an error of about 2~5% over the range of currents from 0~300mA.

2)I have two loads ,drawing ca. 272mA and 27.2mA simultaneously.When I disconnect 272mA load,I find that the output from the 27.2mA rises by 2mA (20mV).The voltage at the shunt,does not change,only the amplified voltage at the output.I swapped the loads,and found that the same behavior is on both the channels.

TIA.


texts: Does the energy the top load of a spark gap tesla coil discharges have enough amperage to kill you?

texts: I am building a SGTC for my science project, and I thought it would be really cool to be able to hold onto the toroid. But, I don't really want to die. So, I wanted to know how many amps the toroid discharges. Also, if something other than the amps would kill me, could you mention that to?


texts: Analog to Digital conversion for an old analog synth

texts: I'm trying to convert an old analog synth into a digital one. I'd like to bypass the speaker and read the values of the speaker with my arduino. But I don't know how to do it


texts:
First of all this is not related to a HW or anything; I just wanted to build an audio amplifier and test my skills.
I really don't see why my design is not working as intended, without the speaker load it amplifies the input signal just right but when I connect the speaker load (4 Ohm) the power of the speaker is limited to microwatts. Can anyone help?
Sorry I didn't sketch the circuit in the editor since I already had drawn it in LTspice
P.S. I actually have built the circuit but I can barely hear something coming from the speaker when I blow on the mic.


texts: Can a multiplier be used to multiply larger numbers?

texts: Can you do 8 bit multiplication easily with a 4 bit multiplier.  Efficiently.


texts:
I'm designing an op amp circuit to amplify 20mV, 18kHz square wave up to measurable levels (~2-3V). Why is the output signal:

Biased at ~400mV
Triangular (high output capacitance? is that a thing?) ?

Op amp is chosen to have maximum slew rate (1V/uS).

As suggested, I've tried a couple of higher-GBWP op amps and none of them work for some reason. Why is that?


texts: USB-Battery load sharing circuit comparison

texts:
I have found two different load-sharing circuits on Adafruit modules:

The 32u4 (left) only employs a schottky diode, while the nRF52 (right) uses an additional pull-down resistor as well as a transistor.

Since the 32u4 design is simpler, what are its drawbacks?
Does it also allow having VBUS and VBAT connected, or can VBAT damage VBUS?

Thanks in advance!


texts: Connecting many electromagnets with polarity control

texts:
I'm trying to see if it's possible to build a large grid (hundreds) of electromagnets, where very electromagnet should be able to get both directions of currents (to generate magnetic fields with both polarities). A simplifying condition is that only a single electromagnets has to be active at a given time.
Controlling multiple EM's can be done with bitshifters and Darlington arrays, while making a bi-polarity EM circuit can be done with an H-bridge. I'm having trouble combining the two. Darlington arrays seem to only come in NPN flavor, and not the PNP that one would need to complete the H-bridge type circuit (if my understanding here is correct.) I was hoping to avoid making an H-bridge for every EM, especially since only one EM needs to be activated at a time.
Is it possible to make a circuit with these requirements in a scalable way?


texts: Heat sink, how much does fin and base width matter?

texts:
I have lot of aluminum sheet 0.5mm thickness at home, normally heat sinks that I have seen had 1mm thickness.

Now I am wondering should I get that sheet welded as heatsink or do I absolutely have to invest in thicker sheet for efficient (at taking away and disposing heat) heat sinks ?


texts:
I need a small (3 cm), 90° angled lightpipe to redirect a 0.5cm LED.

I'm looking for a DIY solution using common materials I already have at home. (Even if it won't redirect all the light it is still OK).


texts:
I am working with RGB LED, my question is will it burn up / get damaged

I have already chosen resistors proper for each color of R G B to draw 20mA, but running R G and B at same time draws lots of current (55mili) and shines very bright white light is this safe?

here is the picture of the schematics

http://prntscr.com/6itvec


texts: Amplifying instruments by measuring current in conductive strings

texts:
The normal musical instrument pickup uses a magnet inside a coil, and the movement of a ferromagnetic string causes changes in the magnetic field, which then induce currents in the coil.

Another possibility would be to use just a strong magnet near a string, and measuring induced currents in the string itself.  This would only require a conductive string, not a ferromagnetic one.

Does anyone actually use this method?  Is there a name for it, or is it useless, so no one talks about it?  I tried it last night, and it works, but the signal is very low (-50 dBV, for instance, vs -5 dBV for a magnetic electric guitar pickup).


texts: Sensor has interrupt pins. What can I connect them to?

texts:
I have a BMI055 gyroscope and accelerometer. on the sheet there is a section dedicated to the 4 interrupt pins (16,1,12,13 respective to 1,2,3, and 4). This section starts on page 30. and it seems that these pins are set to the high state whenever new data or a change is detected.

with a 4 pin SPI setup, is there a specific pin function that i need to connect it to on my microcontroller, or can I hook it up to an ExtINT (External interrupt) pin?


texts: BIBO Stability considerations for Transfer Functions

texts: So I was wondering if you have a system, consider it \$G(s)\$ and it has no initial energy i.e. \$x(0) = 0\$ for the initial condition. If the transfer function exhibits: pole cancellation, would it be considered stable. I know this is a common paradox in the discipline ,but with the knowledge of an already "energyless" system that will only respond to a simple input/output relationship. Does this actually affect the stability for controller purposes?


texts:
I'm trying to drive a 12V LED with an arduino acting as an encoder: a PWM signal with 80% duty cycle ("1" symbol is +5v for the 80% of the time, 0v for 20% of the bit-time) . Testing the maximum frequency supported by the cricuit/driver/led, I get a bit-time of 1/1500 sec-1 with a cyclic message 101010... Above that frequency the led begins to blink. I wonder what should be improved to get a bit-time of 1/5000 = 200 nano sec.
The circuit from Joost Damad is attached.
Arduino LED Driver


texts: If cells in series are mismatched in capacity, will the capacity tend to even out?

texts:
A closed question is about cells in parallel, and does have hints about series, but it also has contradictory answers and comments.

We have more than a dozen alkaline AA cells, and the only current test method (without going out and buying another device) is to put them in a TV/satellite remote and look foe a "change batteries" message on the TV screen.

But the remote takes four, and if we get that message, it's possible one or more of the cells is still good.  They're cheap, so it would be reasonable to just dump all the unknowns in a recycling bin and buy more, but if we keep using them until we see the message, are all of them pretty much empty?


texts: Serial nested if statements (Not working)

texts:
I have been trying to get this to work for a few days.

What i have at the moment is TouchOSC installed on my Iphone sending commands to a processing program, which in turn simplify's them and sends them off to my arduino through serial.

This is where my problem is the commands get there and I can print them out easy enough. They arrive correctly. Format is t11 or t10 (t for toggle control, then # for id of control changed, the last # is on or off (1 or 0)

Now when I try and break this down with if statements it never seams to work. I know the data is correct when it gets to the arduino.

I need to test if the first char is a 't' simple if statement

if(Serial.read() == 't')

before this i test if

Serial.available()

is true
then through similar if statements i test if next is the number '1' or '2' for the control id, then if number is on or off, '1' or '2'

When i test this in Serial monitor or with real data off my phone never seam to get into the loops or will get it to one and not the other. Some times i can tweak it to get into all of them to switch the LED on, but then won't turn it off or vica-versa

Can anyone please give me an example of the logic that i need to use, i have also tried using switch statements for the ID doesn't seam to make much difference

Thanks


texts:
I currently have a project where I need to control a servo using OCR1B. I already figured out how to use one with Timer0, but I can't use that for this project though.

So, my questions are:
  - How do I set the PWM frequency to 50Hz(for the servo)?
  - How do I change the Duty Cycle to set the servo position?

Also my system clock is 1MHz.

Thanks for answering!


texts: Current/Voltage measuring using Ammeter/Votmeter

texts: I have to measure current/voltage of an unknown circuit. So why should I start with the highest rating and gradually come to a smaller value to identify the current/voltage? What's wrong if I start with the small value to measure that current/voltage?


texts:
I have Found One Circuit Which acts as Switch to Pass 15NV (15 Negative Voltage) to Opamps Negative (-VCC) Supply But I am unable to understand its working . Why Two NPN are used in this Circuit ? What is the Purpose of Capacitor C1 ? R3 is used to limit current or has different purpose ?
Please Help me understand the Working of this Circuit and its actual Usage .


texts:
Connecting a DHT22 sensor to an ESP8266, I can't read the serial data sent back from the sensor.
I'm almost sure this is a problem with the sensor communication not reaching 0 V as the software always reads a logic 1 on the pin. If I connect it to GND, it does read a logic 0 so it's not a port problem.
How can I make it reach 0 V? Where is this offset voltage coming from?

PD: This doesn't work with any DHT22 library for Arduino, nor with my FreeRTOS code.
PDD: I've tried using an external 10K pull-up and the internal pull-up from the ESP8266.
EDIT:

simulate this circuit – Schematic created using CircuitLab


texts:
I want to detect if the electronic locker in my differential is functioning. The differential locker is essentially a solenoid that engages the axle locker, however since the wire runs under the vehicle it is exposed, and a damaged wire would go undetected. I have no way of mechanically detecting it (limit switch, plunger, etc), so I need to do it electrically.

The locker's solenoid operates on 12V and draws between 5-8 amps, so assuming the higher value, the locker has an effective resistance of between 1.5 and 2.4 ohms.

I have found some 10A shunt resistors with a voltage drop of 75mV (I'm guessing that means 7.5mohm), which will have minimal impact on the operation of the solenoid. My calculation is that my actual voltage drop will be between 37.5mV and 60mV.

I'm not trying to measure the current, just detect it by lighting an LED (most likely a lighted switch which expects 12V. Most of the articles or information I've found reference OpAmps to measure current, but I just want to detect it, so presumably I would use a PNP transistor, but which one?

I have done some searching, but I don't even know if I'm searching for the right thing.


texts: What is the dead time in between two subsequent outputs in the CD4017 counter?

texts: I would like to find out the dead time between subsequent outputs in a cd4017 counter set up in astable mode.I unfortunately do not have a scope to run an experiment myself.


texts: Rotary switch that changes resistance on each click?

texts:
I am trying to create controller for my car head unit as it lacks a volume knob amongst other things.

I have worked out that when tapping onto the control pin I can "send" commands by applying a resistor of specific value between two pins:

1000Ω = Volume up
3300Ω = Volume down

I can achieve this using a button or switch method simply by putting the resistors on those items however I would like to create a volume "knob".

Is a rotary encoder the thing I will need here? Could somebody provide a little more direction on how to achieve the above functionality? As it will need to change the resistance each click yet reset it before the next click, it will also need to continue to spin rather than reach a limit.

Picture (may help)

Thanks again


texts:
I bought this relay module and I tried connecting it to my raspberry pi. I attached the Vcc (one next to the inputs) to the 5v rail of the pi and gnd to gnd. I attached the input pins to various gpio pins and when I try and switch it on, it doesn't work. I followed this question and checked my module and all the tests passed. What should I try or should I just request a refund?

All answers appreciated!

EDIT: Powering up relay with JDVCC jumper on, and connecting each one of the input pins to ground does work. My power source is a 5v power supply up to 2 Amps. The states are switched on this relay, makes sense.


texts: If I use 10mA for 40 milliseconds. How much current have I used in mAh (milliamperes per hour)?


texts: Can Printed Circuit Boards or other electronic devices (Integrated Circuits, transistors) be damaged by water if the electricity is turned off?

texts: Is it possible that electric or electronic devices be damaged by exposure to water if the current is turned off during their exposure to water and the electricity is switched back on only after the water is completely dried off ?


texts: Depletion region of an NMOS and insulator

texts:
I'm trying to get a better understanding of what the electrons and holes are doing when an NMOS is in the depletion region.

So far I understand that the holes in the P- substrate are attracted away from the gate, leaving negative ions behind. These negative ions now mirror the charge on the gate. This then forms a depletion region. No free charge carriers, meaning no current. Is this correct?

If it is, how are the negative ions being mirrored?

I also get that the Si02 acts as an insulator but now I don't even understand why it is there? If it wasn't what would happen?


texts: Realtek 8188 WiFi module continuous transmit mode

texts:
I'm going to certify an appliance with a RT8188 WiFi module, for which I did the Android port and wrote the software. The certification laboratory is now asking me to write a test software that can put the module in Continuous Transmit mode to test every channel, data rate and output power for compliance within the European standards. Nor the module distributor or the appliance engineers can help me with documentation or example source code to fulfill this task. Digging in the Linux driver I've found few hits, bot nothing useful.

Any hints? Thank you in advance.


texts: Why different battery voltage does not affect LED light-up time?

texts:
I have this clock circuit build along with de-bouncing circuit - https://www.youtube.com/watch?v=6O6xdOexSCE (this is based on Ben Eater's 8bit computer). But I'm using 9v battery instead of 5v one. I wonder why battery's voltage does not affect the de-bouncing circuit LED's light up time?
Math is pretty simple for calculating the time it lights up after button press but I wonder why voltage has nothing to do with calculation:

1000000 ohms (1M) x 1E-06 farads = LED stays lit up for 1 second


texts: Purpose of pullup resistor in BJT LED driver circuit

texts:
One answer to this question suggests the following circuit to drive a LED from an open collector output of a 74LS47:

simulate this circuit – Schematic created using CircuitLab

What is the purpose of the R1 resistor? What would happen if R1 would be missing?

I did a simulation, but could not find a different behavior regardless whether or not R1 was present.

(I could have added this question in the original question as a comment to the answer, but I did not want to make the already excessively long list of comments even longer. Therefore I created a separate question. I hope that is OK.)


texts:
I'm working with a SPICE model of a MOSFET that provides a fourth pin for setting the device temperature (driving the pin with a voltage in simulation sets the temperature). However, I don't plan on playing with the temperature in simulation and the extra pin means I'm not able to use a standard MOSFET symbol, which is annoying.

I'd like to eliminate the external temperature pin and set the voltage of that node internally to 25 V. What would I have to modify in the following netlist? I'm thinking I would have to add the directive:

VTEMP 50 0 25

in the section labelled *TEMP SECTION, but I'm not sure if this is correct.

*FDV301N at Temp. Electrical Model
*-------------------------------------
.SUBCKT FDV301N 20 10 30 50
*20=DRAIN 10=GATE 30=SOURCE 50=VTEMP
Rg 10 11x 1
Rdu 12x 1 1u
M1 2 1 4x 4x DMOS L=1u W=1u
.MODEL DMOS NMOS(VTO=0.82 KP=4.12E-1
+THETA=0.25 VMAX=1.5E5 LEVEL=3)
Cgs 1 5x 8.5p
Rd 20 4 0.7
Dds 5x 4 DDS
.MODEL DDS D(M=3.61E-1 VJ=8.34E-1 CJO=12.08p)
Dbody 5x 20 DBODY
.MODEL DBODY D(IS=7.78E-9 N=1.946325 RS=0.023193 TT=15.97n)
Ra 4 2 0.7
Rs 5x 5 0.5m
Ls 5 30 0.5n
M2 1 8 6 6 INTER
E2 8 6 4 1 2
.MODEL INTER NMOS(VTO=0 KP=10 LEVEL=1)
Cgdmax 7 4 75p
Rcgd 7 4 10meg
Dgd 6 4 DGD
Rdgd 6 4 10meg
.MODEL DGD D(M=0.270882 VJ=4.24E-6 CJO=75p)
M3 7 9 1 1 INTER
E3 9 1 4 1 -2
*ZX SECTION
EOUT 4x 6x poly(2) (1x,0) (3x,0) 0 0 0 0 1
FCOPY 0 3x VSENSE 1
RIN 1x 0 1G
VSENSE 6x 5x 0
RREF 3x 0 10m
*TEMP SECTION
ED 101 0 VALUE {V(50,100)}
VAMB 100 0 25
EKP 1x 0 101 0 2.2
*VTO TEMP SECTION
EVTO 102 0 101 0 .003
EVT 12x 11x 102 0 1
*DIODE THEMO BREAKDOWN SECTION
EBL VB1 VB2 101 0 .08
VBLK VB2 0 25
D 20 DB1 DBLK
.MODEL DBLK D(IS=1E-14 CJO=.1p RS=.1)
EDB DB1 0 VB1 0 1
.ENDS FDV301N
*FDV301N (Rev.B1) 5/15/02 **ST
*FDV301N (Rev.B2) 10/1/13


texts: ADN8810 control frequency from Arduino Due

texts:
Resurrecting a 3 year old project. I'm skilled software engineer but new to electronics so it's a bit of a walk in the wood at night without a flashlight. The pcb has a ADN8810 - 12-bit current source with an adjustable fullscale output current of up to 300 mA. My understanding is that the output current is controlled by SPI.

So the question is: what is the maximum frequency I can change the current if ADN8810 is controlled by Arduino Due via SPI protocol?


texts:
When we deal with a transistor we break it up into two parts,
1 The DC bias.
2 The small signal perturbations.
Then we add the currents/voltages from the both the analysis to get the total response.
But what is the proof that we can do this procedure?
As an example say I've a DC source V and Ac source W.
When I apply V at VCB  I get x as a response.
Then I use the small signal model and find that when I apply a small voltage W I get a response y. The total response is then x+y.
However isn't it possible that if i apply V+W together I would end up with a different response?


texts: K018A DIY Kit 200V 500W Light-Dimmer Module - will it work w/ 120v or is modification required?

texts:
K018A DIY Kit 200V 500W Light-Dimmer Module - will it work w/ 120v 60Hz?  Or does it require modification to do so?

Bought this DIY Kit for further practice with my soldering iron, and also to tone down my stand-alone soldering iron of 60w (it doesn't have any circuitry).

You can find this DIY Kit on eBay cheap enough, and it gives a standard lighting dimmer circuit.  However, there are no instructions, and doesn't say where the input/output wires go.

All the components have been cataloged in a spreadsheet w/ reference to corresponding datasheets, as stated to always do on AfroTechMods - One of my favorite totorials on YouTube.  Also Colin's Lab with Colin Cunningham, & EEVBlog w/ Dave Jones are also favorites to watch and learn.

So, what do I do to Americanize this lighting dimming control module?  Or scrap it and buy another one?


texts: Separated powers and high power switches? Alternatives to relais?

texts:
I want to use an Arduino (5V, 0-40 milliamps) to control some switches, which in turn control a high current line (12V, 40A). But the relays which I use use too heavy coils for the Arduino to pull off.

The relays don't turn on.

What are my alternatives to relays and separating the low power Arduino from a high power line?

Is there a way to use MOFSETs (in regards of separating the power lines)?


texts: How can I connect a CT clamp (AC Current sensor) to a multimeter?

texts:
I have ths CT clamp (with a 3.5 mm jack on the end):

https://openenergymonitor.org/emon/buildingblocks/report-yhdc-sct-013-000-current-transformer

How do I connect the clamp output to the multimeter probes to get a current measurement?

Also as a novice, what is the multimeter setup (wirings and modes). I am expecting to clamp this around an electrical heater appliance (the live wire).


texts: Electret microphone and microphone amplifier with a bipolar transistor

texts:
The circuit to the right in fig. 1 is a CE that amplifies the Vin signal from an electret microphone (input to terminal J1-2). The output impedance of the electret microphone is about 20 kΩ (the output of the electret microphone is the D and S terminals of a JFET; see the model in figure 2, where the R and C external to the capsule correspond to R6 and C1 on the amplifier). The Vout output (J2-1 terminal) will be attached to the node between C2 and R5 (i.e., the potentiometer has the upper and middle terminals connected). For BC549C use β = 500 and the remaining parameters given in the header.

In the header the information given to me are as follows:

Figure 1 and figure 2:

I need to calculate \$I_{C},V_{CE}\$ of polarization in the transistor Q1 and the DC voltages of the entire circuit.

I did not understand the statement. I did not realize what the microphone is and what the amplifier is. And I do not know how the final circuit is to be able to do the math and where that output impedance is located.
I would appreciate if someone could make a drawing of the complete circuit and put me the calculations of the parameters that ask in the statement, I am very confused and I am beginner. It's been several days since I've looked into this problem and I do not know what to do. You are my last hope!


texts: Which is the best, clean way to join wire together

texts:
I am installing CCTV cameras and I'm using a 3A adapter to supply power to the cameras, but I have very messy results when trying to join together very small wires with electrical tape.

Is there any clean way of doing all this? For example, how can I join together the wires of 3 power supply cables? Also, how to join the Audio/Video lead to the normal wires? I find it very hard to first cut the A/V cable and then use electrical tape to join them.

I want to make something like this, but it's not as clean. It looks messy with electrical tape.


texts: Is the ground necessary with an opto-isolated RS422 signal

texts:
I have 8 opto-isolated RS422 ports to install.

All of them are coming from a single PC card. It provides the opto-isolation for every RS422 port. Every signal is opto-isolated from the PC ground and from each other port.

Does every RS422 port require its ground signal to be connected to the distant device? I have read both answers, yes and no.

In this document, the "fully isolated" paragraph states:

  A fully isolated RS-422/485 link generally requires a direct ground wire between the two ends. External surge protection is only required if large lightning related surges to ground are expected.

But in this post I understand that it is not necessary (maybe I didn't understand well):

  opto-isolator coupled differential signals

  Systems like MIDI connect more-or-less differential signals to the LED of an opto-isolator at the receiver.

  With proper design, similar systems can and sometimes do work just fine with kilovolts of offset between the system "ground" at one end of the cable and the system "ground" at the other end of the cable.

So, should I or shouldn't I use the proper ground for every RS422 port?


texts: Electrical properties of a stack of strip board connected by through-hole pins/sockets

texts:
I'm aware that breadboards have a limit of 1-2MHz.  I think this is because of capacitance.

Are there similar limits for a stack of stripboard connected by through-board sockets/pins?  Would breaking all the tracks, to make them as short as possible, help?


texts:
I'm trying to connect  A4 to pin 5 in 6050 in the picture.

When I click those with the net tool, it also connects A2, which is not what I need. If I use the delete tool and erase the junction, they are still connected. How can I just connect a4 to 5?


texts: How do you interface with this sensor? MPS-2100series

texts:
I am trying to figure out how to get a reading from this sensor. At first look at the schematic, it thought it was wheatstone bridge, but at a closer look, it appears to be a resistor ladder type circuit, but I don't understand what it is doing.

Can someone fill me in?

http://www.metrodyne.com.tw/datasheets/en/MPS/MPS-2100series.pdf

Thank you


texts: Why ATPG DRC check is done if DRC check is already done at Scan insertion stage?What is the difference between both the DRC checks?


texts: Looking for links to projects where video decoders are used as general purpose ADCs

texts:
The pricing for high speed ADCs is very high. However, since video decoders are used in just about every flat panel display, and these generally contain a couple of ADCs, their prices are very low.
So, the obvious question arises. Is it possible to use a video decoder as a multichanneled general purpose ADC....and even interleaving the channels to increase the bandwidth further.
I've been scouring the web and haven't been able to find any papers or DIY projects doing this. If anyone reading this is aware of any such projects, then please point me towards them. I'd love to see if this is possible (both using them channel by channel and interleaving the channels to get an even higher sampling rate).
In terms of pricing, a video speed general purpose ADC would cost in the order of $30 per chip, whereas the video decoder would be priced at about $3 per chip, a pricing order of 10:1 !!!!
So, if you know of a project or paper related to this, please pass on the link. Many thanks in advance.


texts: Visualising redundancy in a 1.5 bit pipeline ADC

texts:
In a pipeline ADC, we have redundancy where  we increase number of levels  to somehow more accurately measure the input and reduce the error.
In the manual shown below we see a redundancy example from a Maxim tutorial.
They don't show in the example how exactly given an error the redundancy fixes it.
They only say that we fix the problem by doing right shift to the bits and summing the stages data.
I think digital fixing is not redundancy.  I can't see how in case of an error redundancy helps me with figuring the correct location of digital value.
https://www.maximintegrated.com/en/design/technical-documents/tutorials/1/1023.html


texts:
I am working on a Geiger counter circuit which utilizes a boost supply similar to the one shown below to polarize the Geiger tube.  The tube datasheet specifies a maximum voltage of 475 V.  However, I'm not really sure how to interpret this in the context of a boost supply.  If the tube is an open circuit in the absence of an ionizing particle, does not the boost supply continue charging the capacitor to an infinitely high voltage in theory?  When I measure the tube voltage using a 10x multimeter I get 270 V and when I measure it with 100x I get 432 V.  I presume if I kept stepping up the input resistance of the multimeter that the measured voltage would continue to go up.

Is it even possible to really know the open circuit voltage of a boost supply?  And if not, how do I know that I have applied the correct voltage to the Geiger tube?  By the way, the tube is actually working so this is mainly an academic question at this point.

simulate this circuit – Schematic created using CircuitLab


texts: How to filter low frequency noise on power supply from ChipCorder?

texts:
I've built a circuit using an ISD4003 ChipCorder, which is an IC for recording and playback of audio (in a telephone answering machine, for example).  I've written code to send the SPI commands to record and playback audio.  The problem is that whenever I command the ChipCorder into record mode, I get loud low frequency noise recorded over top of my voice.  The noise only exists while the ChipCorder is in record mode.  The noise is less than 200 Hz with a dominant frequency of 40 Hz.  (It sounds like a cross between a buzzing bee and flatulence.)

This is an excerpt of my circuit schematic.  That's an electret mic going through a high pass filter and a preamp before the AUDIO_IN signal goes into the ChipCorder.

I know the noise is generated by the ChipCorder because the noise only occurs while the ChipCorder is recording.  I believe the noise is going over the power lines and being picked up by both the mic and preamp.  If I power the mic and preamp with a separate power supply then the recording is clean with no noise.  But that was just a test, not a solution.

I changed the corner frequency of the high pass filter to 300 Hz to try to filter the noise but that wasn't enough.  I even tried adding another first order high pass filter after the preamp (not shown on schematic) and that still wasn't near enough.  I also tried adding more bypass capacitors (100 uF and 220 uF) in various places but that didn't help.

What else can I do to prevent the low frequency noise generated by the ChipCorder from affecting the mic and preamp?

Also, I'm testing this circuit on a solderless breadboard.  Is it possible that moving to a PCB with a proper layout, ground plane, etc. will have a dramatic affect on this noise issue?  I'd rather fix it on the breadboard before moving on to a PCB.


texts: What equipment do I need to test an eye diagram for USB?

texts:
I'd like to test USB full speed with a goal of testing high speed (480 Mbit/s), I have a tek scope that does 300 MHz (which I could upgrade to 500 MHz) and I'm looking at a 500 MHz differential probe. As I understand it I also need a breakout board (which I'm not quite sure is the best thing to get), but I'm looking at this board from tek and one listed here.

What are the minimum requirements for a test like this?

Is this equipment list sufficient to preform an eye diagram test for full speed USB?

Is this equipment list sufficient to preform an eye diagram test for full speed USB if I have a 500 MHz scope?


texts: I found a schematic, but it requires 2N2222A transistor, is there any alternative? I have only KC637, can I use it? I'm new to electronics, and I'm not from US/UK, so sorry my English.


texts: Can I charge my van's car battery directly from its lithium ion "house battery"?

texts:
I have a 1991 GMC van that I've converted into a poor man's RV.  I've got a Yeti 1000 lithium ion house battery, and a 100 watt Renogy solar panel on the roof.  When the battery has died in the past, I have hooked the ~20v solar panel output directly to the car battery and successfully charged it (checking voltage on the car battery regularly to make sure I don't overcharge).  Can I do the same thing using the 12V output from the house battery?  I'm mostly concerned with damage to the house battery, which costs over $1000.
My exact question is this: If my 12v lead acid starter battery goes dead, can I connect the 12v output (I measure 12.4v) of the Yeti 1000 directly to my starter battery to charge it enough to start the car, as long as I am careful to monitor it to prevent overcharging? And is there any way this might damage my yeti 1000?


texts: Learn C programming before start learning Microcontroller/Embedded Systems

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

I want to know whether it is mandatory to learn C/C++ programming before start learning Microcontroller or the Embedded Systems. If yes, why do I need C to start with?


texts: Electrical Engineering vs Computer Engineering?

texts: I am trying to decide whether to major in EE or CE. To my knowledge, computer engineering has the same core focus as electrical engineering but with an emphasis on digital logic and microprocessors. Are there any major differences that I'm missing?


texts: ESD / TVS / Over-voltage diode selection - leakage current into power supply

texts:
I am choosing an over-voltage protection diodes for input pins to a device. There will also be spark gaps on these lines.

My question is what kind of effect will the leakage current of the diode have on the power supply. I have already read that for battery supplies the battery life can be affected / reduced.


texts: Calculating energy absorbed by an element

texts:
I need your help to understand the solution to the given question where energy absorbed needs to be calculated with the given graphs of the current and voltage through the element. Please help explain below points:

1- How the mathematical equation is derived and why the limits are chosen in the way they are give in the solution?

2- What does area under the graph of the power represent?


texts: Can Cellphones be used for Ad Hoc Communication?

texts:
Can Cell Phones be (legally) used Adhoc, (ie, Point-to-Point) Communication?  For example, let's say I'm in a remote area of the woods, or a valley.  Can I configure cell phones to be used as true walkie-talkies even though neither one of them use has a cell phone tower?

(Besides, it might be handy to use this on, oh, say, a drone, for photography purposes.  I intend to comply with all regulations regarding use of my drone.)

This goes for those modules too, I can hook them up to a raspberry pi, for example.

In the latter case I could just buy a nice antenna, I guess....

What kind of range would either of these things have if they are feasible?

I wanted to get my ham radio license, but I have my second year of engineering school to finish up.

Also: Might you suggest any alternatives (I hope this doesn't make my askance too open- but, it may be worth noting this question, or moreover, it's very upvotable answer! Alas, I doubt they have too much bandwidth...)


texts: Attiny4 - Possible Errata Found With PWM

texts:
I have searched the AtTiny data sheet and not found anything about this. I'm experiencing a weird PWM bug. When I expect 100% on I'm getting less. I'm using an inverted PWM scheme, so setting it equal to 0 should be full on, but my scope shows a ~95% on duty pulse.

Below I posted applicable setup code, then the function I call occasionally in my main() to change the PWM rate... When I set the OCR0B=0, I do not get a full on PWM.

I'll also note all other PWM settings appear to work correctly, the duty cycle matches what is expected.

Anyone want to take a look to check I'm sane before I complain to Microchip/Atmel?

//Setup Pins:
DDRB =  DDRB |  0b00000010;     //set B1 output and B2 to input.
PUEB = PUEB |   0b00000100;     //Pullup on B2

//Setup Timer:
//output pin is OC0B (PB1)
//Set PWM Fast Mode 8 Bit, enable output on all PWM pins (only 1 on tiny5).
TCCR0A = 1<<COM0A1 | 1<<COM0B1 | 1<<COM0A0 | 1<<COM0B0 | 1<<WGM01;  //COM0A0 COM0B0 set to 1 for inverting PWM.
//Set PWM top [ICR0] to 5bit (this allows effective 31khz pwm)
ICR0 = TOP_PWM; //Set TOP...
//Set PWM Mode Fast 8 bit & No pre-scaler.
TCCR0B =  1<<CS00 | 1<<WGM02 | 1<<WGM03;
OCR0B = TOP_PWM; //Start with 0 output.

//Setup INO0 (External Interrupt):
EICRA = 1<<ISC00 | 1<<ISC01;    //Enable rising edge interrupt
EIMSK = 1<<INT0;                //Enable INT0

 ----------------------------------------------------------------

/******************************************
* Function to decide what speed to set.
* NOTE: All alterations to motor speed should
*       be done in this function!
* Also note that inverse PWM is used,
* so 0 is full speed, and TOP_PWM is stopped.
******************************************/
void speedLogic()
{
    //Speed logic
    if      (speed_state == 0)
        speed = TOP_PWM;//Off
    else if (speed_state == 1)
        speed = 24;     //Slow
    else if (speed_state == 2)
        speed = 16;     //Med
    else if (speed_state == 3)
        speed = 0;      //Fast (3=91% Otherwise 0=100%)
    else
        speed = TOP_PWM;

    //Set PWM Reg
    OCR0B = speed;

    //Increment State Variable
    speed_state++;
    if (speed_state > 3)
        speed_state = 0;
}


texts: Current waveform distortion on transformer with a load resistor on secondary winding

texts:
Why does the current from a transformer with a load resistor quickly rise and fall (yellow wave-form)?
(Transformer without a load resistor (white, primary)).


texts:
I installed two 4" 18 watt LED light bars on my ATV. It is currently wired to the factory switch on the ATV handlebars and there is no relay being used. I have had to replace the right LED bar twice because it has died on me. Is this because I didn't use a relay? Will the relay help?

As a side note, the battery seems to be failing and not holding a charge well (old battery). When I start the ATV (can't use electric start, pull only), the lights will turn on but they will start to dim unless I rev the engine.

The ATV is a 1995 Polaris Magnum 425 4x4.


texts:
I'm creating an RGB switcher for a car video system and would like to use the MAX466 chip, which needs -5V, GND and +5V. I have no idea how to change normal 12V DC (car battery) to dual 5V.

I found many schematics which convert AC power, but how about 12V DC?


texts: "Performance Density" for a CNN Implementation on FPGA

texts:
In the paper "Improving the Performance of OpenCL-based FPGA Accelerator for Convolutional Neural Network" at table 6 there is a metric called Performance Density. It is defined as the number of arithmetic operations that one DSP slice executes in one cycle. There are the values 2.8 respectively 3.06 ops/DSPslice/cycle reported.

When looking at the Arria 10 DSP in floating point mode, it can execute one multiplication and one accumulation in one cycle (A*B+C). That means maximum is 2 ops/DSPslice/cycle.

Where is the difference coming from? Did I miss something?


texts: 12V signal convert to 5V without interfere

texts:
I have Wiegand 26bit bus.

DATA0 - GND = ~12.5V when idle
DATA1 - GND = ~12.5V when idle

I need some sort of scheme or something to convert 12V signal to 5V without interfere.
I have few thoughts:

Optocoupler. Will the R1 and LED interfere a lot?

MOSFET. What would be the scheme?

MAX232 chip. a bit difficult at the moment to test

Please suggest something for this case.

UPDATE
The scheme of EM Fields does work. But i have one more problem.
There are 2 RFID readers connected in parallel. One is newer version than the other. They are configured to give Wiegand 26bit output.
1 parity bit + 8 bit site code + 16 bit card number + 1 parity bit = 26 bit
When i tried to read i received this

Card number is 140,2193
binary 1 10001100 0000100010010001 1, but i noticed that the older one gives extra 0(marked with red dots) after 1. That means DATA0 line is triggered to low after every 1. Security system reads card correct. What could cause the line go low?


texts: How to convert from 2 data line full duplex to 1 data line half duplex?

texts:
I'm trying to design a circuit that can convert from a two wire full duplex (think SPI), with one transmit line and one receive line, to a one wire half duplex (think i2c), with bidirectional communication over the same line, but I'm having no luck. Is there a specific chip, or a circuit I can use?

edit: the two protocols are (de-strobed and converted to single ended) SpaceWire (or at least SpaceWire hardware carrying I2C signals) and I2C. SpaceWire uses a data in and a data out pin, so I'd like to be able to send an address or command etc. to the I2C device over the DOUT wire, and receive the data through the DIN wire. SpaceWire is a difficult protocol for interface ICs, which are either non-existant or exorbitantly priced. By 1 and 2 wire I'm excluding the clock line since it will be shared between the two protocols.


texts: Why does a DC motor spin when there is no load applied to it?

texts:
So this is a characteristic of a DC motor:

When armature current=0, apparently it still spins quite fast. From what I know, a magnetic field causes a mechanical force on a conductor only when there is current going through the conductor. And in this situation there is no current. So why does it spin?


texts:
I am trying to connect ESP32 Feather board and Thermal camera module using I2C. ESP uses 3V3 and the sensor uses 5V I2C, thus I figured I need a I2C voltage conversion chip. I chose the PCA9306 Breakout board. I connected everything up as shown in the PCA9306 datasheet and even used examples from this. Every time the magic smoke comes out...
I have spent days trying to figure out why it is not working. Read datasheet twice. Re-soldered a new PCA93006 chip 5 times now. Looked at the schematics. Measured every trace with multimeter to ensure all connections are as they should on the breakout board. I drew a schematic how ESP32 and thermal sensor is connected to the PCA9306 breakout board. I really hope someone can tell me what am I doing wrong here. Simple circuit, but I really do not understand why it's not working.
Some notes about the schematic: if I only connected 5V and GND, then everything is fine, but as soon as I connect 3V3 to Vref1, then the magic smoke comes out.

The PCA9306 breakout schematic is here:

I have looked other questions related to 9306 chips and I2C conversions, but I have not found an answer to my question.
EDIT 1: Smoke comes out from the PCA9306 chip on the breakout board.
EDIT 2: I added the testing wiring. I am using breadboard and USB power supply that provides me 5.1V and 3V3 to test the chip. If I power the circuit in the picture then the chip burns. Although, if I switch the vref1 voltage to 5.1V and vref2 to 3V3 and power the circuit then it works, but vref2 is outputting 3.8V. Thus, the voltage difference between vref1 and vref2 is 1.3V. Why is it working this way and if I switch the vref voltages, then the chip burns. As I understand I can't use the 3.8V, because it might damage the ESP32?


texts: What happens if the frequency of the receiver osc does not match (exactly) the carrier frequency?

texts:
I thinking about FM and AM. Theoretically the carrier frequency is perfectly match the demodulation frequency. But what happens if there is a mismatch?

I think using AM the frequency of the base-band analog output will be pitched low/high depends on higher/lower demodulation frequency respectively. Am I right?

But what happens using FM?


texts:
I have been working on a project controlling a coil to attract a metal ball at high speed.
 I measure the speed of the ball in front of the coil and then decide how fast I want the ball to accelerate because the speed it needs to have when it leaves the coil is about 10 m/s.
 I found out I have about 9 miliseconds to use the coil. So what I was thinking is i'll use a MOSFET and a pwm signal in this way i can change the duty cycle and then control the coil.
 But I read on a site if I want this to work I need to switch high side and low side because else the coil still will be magnetic. now is my question: does somebody know what they mean or what I need and how does is work since I haven't got much experience with coils.

Specs:
 PWM signal : 3.3v 10Khz
 Coil: 51v 16A


texts: Implementing Best Linear Unbiased Estimator (BLUE) with real data

texts: I have a set of data contained in an excel file that I wish to compute the Best Linear Unbiased Estimator. I understand the assumption of the signal observed must be x[n]=S[n]A+W[n], where S[n] is the true signal and W[n] is white noise. I am having trouble trying to figure out how to compute A. My goal is to write code that computes BLUE given a set of data. Given that I could not find any examples on how to compute BLUE given real data from a file, my question is, are there any suggestions or pseudo code that explains how? Or can anyone point me towards the right direction. Thank you.


texts: does a serial port have enough power to drive a comparator circuit?

texts:
I am trying to use serial port pins to power this circuit.  Basically I want to send a voltage high to pin 8 when somebody "opens the box" that this circuit is in.  Otherwise, it will send a voltage low when the box is closed.  I can detect this in software just fine, my question is with hardware.

Will the serial port be able to power this circuit?  I looked at the LM339 datasheet and it seems like the current needed is pretty low, but i dont know the serial port's power capabilities.  Any advice would be great, thanks!


texts: Is there any wearout mechanism for a relay simply from current flowing?

texts:
How will the wear of a relay be affected if the current through the relay is brought to zero before the relay is operated?

I'm thinking about having a solid state relay in series with 3 mechanical relays. The 3 mechanical relays will all be connected to the output of the solid state relay, and channel the current to one load each. Thus there are three loads, and three mechanical relays. I can arrange to turn off the solid state relay before opening or closing any of the mechanical relays.

Can I assume that the lifetime of the mechanical relays will be equal to the speciefied mechanical lifetime of the relay, or will current flowing through the closed relays somehow cause aging in and of itself?


texts:
I have a query regarding selection of SerDes ICs. I need to select an IC which is compatible with 3 formats - 24bits, 32bits and 27bits.
MAX9275 - Just a sample IC datasheet in the MAX SerDes GMSL family.

My question -

Can someone tell me what those 3 formats are and what they mean?

And how to search and find that information in the datasheet attached above

Any useful tips and information along the way regarding this question will help me a lot to select a particular IC in the MAX SerDes IC family.
EDIT:

I found that in the above image, 24 bits, 32bits and 27bits, how are they arrived?
RGB either comes as 666 or 888. So, RGB + Clock will either be 6667 (25bits) or 8887 (31 bits) ? Am I correct? Or what is the actual split up of 24bits, 32bits and 27bits? And why 27bits is specifically mentioned as high bandwidth mode?


texts:
I have always had problems with my wireless doorbell solution. Since my driveway is around 50m (160ft) the signal is never quite strong enough to trigger the bell all the times.

So I was thinking about creating my own wired solution, but my question is how I would make this work.

Would a let’s say 5v DC signal be able to travel this distance and still be picked up by a microcontroller? Or is there maybe a better way to make this happen (using AC and converting it to DC at the gate)?


texts:
Today, I started noticing a clicking noise (at a frequency of maybe 0.5Hz), and after a while, located the source as an alkaline AAA battery powering noise canceling headphones.

The battery did not look all that heavily corrupted, but was leaking fluid when handled. I decided to dispose of it ASAP rather than let the scenario play out any further.

However, I'm curious as to what exactly I might have been hearing. I found some discussions speculating on the phenomenon on the internet, but none of the answers looked really high quality. What could be causing such a rhythmic clicking?


texts:
I'm using an STM32F103C8T6 (aka blue pill) with Eclipse/System Workbench and HAL.

The following code:

 volatile HAL_StatusTypeDef result =
  HAL_UART_Transmit(&huart1, bytesToSend + currentSendIndex,
  bytesPerMessageToSend, 100);

 volatile uint32_t error = HAL_UART_GetError(&huart1);

works fine when sending 1 byte, and (later) receiving 1 byte and iterating this.

However, when sending 3 bytes, I noticed, I only receive the first byte, and the next calls for HAL_UART_Receive result in a timeout.

This seems logical, because probably there is only 1 byte buffer in the UART.

However, what I don't understand, why does transmitting multiple bytes in the code mentioned, returns HAL_OK, and also the call to HAL_UART_GetError returns 0.

I assume an overrun has occurred for the 2nd and consecutive bytes... is this true, and if yes, how can I check this?


texts: DSPIC30f timer1 not trigger everytime on POR

texts:
I am using timer1 on DSPIC30f4011 to generate an interrupt every one millisecond. However, the timer1 ISR is not executed every time on POR (2 out of 10 times). If I turn on the power for the chip and use MCLR (switch it to high or low) the timer will work everytime on a MCLR reset. Is there anything that I need to clear in the software? I already reset the timer1 flag.

unsigned char t2=0;
unsigned char  t1=0;
unsigned char t0=0;
void main() {
  ADPCFG=0xff;
  //timer1 setting##########
  T1IF_bit= 0;                     //clear flag
  IEC0.T1IE         = 1;           //enable timer1 interrupt
  IPC0=0b0100000000000000;         //priority
  PR1                 = 7373;      //load
  //###########

  UART2_Init(115200);             //output something to computer

  ////////
  T1CON.TON=1;  ///start timer1
  ////////
  while(1){

    UART_Write(t2);
    UART_Write(t1);
    UART_Write(t0);
  }
}
void Timer1Interrupt() iv IVT_ADDR_T1INTERRUPT{

  T1IF_bit= 0;  //clear the flag
  t0++;         //increment something
  if(t0==255){t1++;}
  if(t1==255){t2++;}
}


texts: Beam Steering range of a phased array antenna system

texts:
What is the beam steering range of a phased array dependent on? For example, if I use an antenna array of Nx1, with a phase shifter resolution of \$\frac{2\pi}{k}\$ and the antenna elements spaced at \$\frac{\lambda}{2}\$, what is the beam steering range?

Also, the beam steering angle, \$\theta\$, for phase shifts of \$\phi, 2\phi, 3\phi,....\$ and antenna element spacing of \$\frac{\lambda}{2}\$ is \$\theta = sin^{-1}(\frac{\phi}{\pi})\$ right?


texts: Thermistor with LM358 Dual OpAmp Circuit Validation

texts:
Given the circuit layout here with a 9V input and the 10k ohm thermistor specs given, what at what temp would the green LED light and at what temp would the red LED light?

I am expecting green to come on at about 17.5C and then red to come on at about 37C. Green and red should never be on at the same time and nothing should be on at under about 17.5C.

Is this correct?

Would it work without change for a 3V input? If not, what would need to change?


texts: What's the reason for this symmetry argument?

texts:
Okay so I've learnt about various methods to find equivalent resistance in circuit. But there's one particular argument which I don't understand and I would be grateful if someone  will prove it using symmetry arguments.

In this figure, for sake of clarity resistors have been represented by straight lines (not by jagged lines).

Symmetry argument that I don't understand: The current entering the resistor AC is the same leaving in resistor FB (same is true for other symmetrical parts of circuit).

I will tell what I mean by saying 'symmetry argument.'
For example in this circuit (again for sake of clarity I represent resistors by straight lines)

It immediately clicks inside my mind that paths AHFB, ACGB and AEFB are equivalent so physics and nature will not discriminate between any path, thus same current will flow through resistor AC, AH and AE making potential at C equal to H and E. This is a satisfactory symmetry argument.

As for the top circuit I can't find a satisfactory reason by myself that why current entering resistor AC equals current leaving resistor FB. Maybe it involves changing polarities of the cell?

NOTE: Please don't tell me about the answer (i.e. equivalent resistance) I'm sure I will find the answer myself once I will find the reason of the question mentioned above. I want to feel that 'Aha' moment once will find the correct answer myself. So please help me.


texts: Are the silver terminal caps the only conductive parts on an AA battery?

texts:
With AA batteries, are the silver terminals the only conductive parts on an AA battery? That is, is the outpost ring around each terminal (part of the body casing?) conductive? I'm asking because I'm thinking to use conductive fabrics as terminal contacts. Because they're soft, they could wrap around the terminal.

Thanks


texts: Raspberry Pi crashes When 3.3v or GND on GPIO connected to breadboard

texts: I'm new to Raspberry Pi and electronics in general and I've been having trouble with GPIO. I've connected the GPIO pins to the breadboard with a ribbon, but then when I use jumper wires to connect either the 3.3v pin or GND pin to the + or - vertical rails respectively, my Pi crashes and won't turn back on until I unplug the wires. Why does this happen and how do I fix it? I've included a picture of my setup.


texts:
We will create an ARM board with a GSM modem on-board.
We want to be able to upgrade the ARM firmware over the air.

Is there any good, reliable, open source solution for that?
If not, is there a paid OS with this feature?


texts: Could anyone explain the two-ray ground-reflection model in plain English

texts: I am studying about wireless communications and I need to understand the two-ray ground-reflection model  for one of my assignments. However, I fail to understand it. Could anyone provide a description of the two-ray ground-reflection model  in plain English that could be helpful to me and others in future.


texts:
I have STM3220G-EVAL board (STM32F207IG MCU). I'd like to measure (approximately) its actual Ethernet throughput (board <-> Windows PC).

I have CubeMX sources. There are several examples (TCP, UDP, TFTP, web server). Which protocol, parameters and algorithm should I use? For example, passing file splitted into datagrams of certain size and so on.


texts: Why is a Transistor called a Transistor?

texts: Okay now I know how a transistor works, but how can it transfer resistance? I am not getting it because all I know about Transistors is that "A Transistor is used to control the flow of current in a Secondary circuit using a Primary circuit." But how does it transfer resistance?


texts:
I am conducting an experiment, and a hugely important part of the experiment is a solenoid and an iron rod. If the solenoid has current going through it, and I place the iron rod so that it is not fully inside the solenoid, it will pull it inside the solenoid. It is this property of the solenoid that I want to use for my experiment. To do it, I need to know the numerical value of the force exerted on the iron rod by the solenoid at any particular position. After some research, I found an expression for a force that might work, but about which I am a little unsure about. The equation states that F=

Where N is the number of turns, I is current, A is the area of the solenoid (cross-sectional area I assume, though I could be wrong), and g is g is the length of the gap between the coil and the iron.

I do not have much experience with this topic, but intuitively, this equation seems to give me the average force acting on over the entire range of movement, rather than the force that acts at a particular point, because it seems to me that the force increases the further in the iron rod is sucked. So I guess what I am asking, is how to modify this equation to give the force at a single instant, or if this is even the equation to use? Or is this more of a calculus question and should I put it on mathstackexchange?


texts:
Recently, I made a small measurement system with three boards. Below is the block diagram:

The power ground cord is connected to the chassis at power entry. I think I need to connect the GND to chassis. Physically, the front board and power board is near to the power entry. At first, I only considered the point where the power ground cord connected to chassis. But, imagine that if my input signals are with great common mode voltage regards to my 'GND', then the common mode current need flow along the relative long power supply paths to the chassis, so I think I can ground the 'GND' at the front board too. Then the current can flow to chassis more easily.

Which is better?


texts: Capture PPS timing signal into PC with minimal latency

texts:
I am looking for a 20 us wide TTL signal to be ingested into my device so that I can sync my OS to a PPS (pulse per second) with chrony.
I'm currently looking at all the ways to have the signal enter my computer. One of them is GPIB. From searching online, the only adapters/converters for GPIB seem to be USB and RS-232.
Is there any way to convert TTL to GPIB? I know I can convert TTL to USB and 232, but is there any way to cut out the middle steps since I imagine that'll cause delays, degradation, and would probably be better to just to have TTL to USB/232 (which I already found ways).
I even tried finding a way to convert it but I'm not sure how the handshaking and management buses would work (would I even need that)?
From looking online (including here), USB appears to be a bad choice due to the "stack", being slow (due to everything sharing a bus?) and such but I still dont understand why. It seems like itd be fine but apparently not. Currently nothing in my system uses GPIB. I just figured no stone should go unturned.


texts: Same LED, different voltage drops with different supply voltages

texts:
I have an LED with no specs for it. I decided to measure the voltage drop across the LED, so I connected it to 5 V power supply and 325 ohm resistor. I measured the resistor with multi-meter, then I measured the current and I had 6.38 mA. I then calculated voltage drop across the resistor which was 2.07 V (\$IR=V\$) and then I calculated the voltage drop across LED which is \$5-2.07 = 2.93\mathrm{V}\$. So I wrote down my voltage drop across the LED.

The day after I was using the same LED on 3.3V circuit. I decided to measure the LED's voltage drop again and it turned out to be 2.633 V and according to Kirchhoff's law it would affect my current because I am connecting this LED before the resistor.

Can somebody explain to me what happens? Why is it that the same LED has different characteristics with different voltages?


texts: Low Signal from Single Transistor Pierce Oscillator Mysteriously Turns High

texts:
Yesterday, I was attempting to build a single-transistor Pierce Oscillator based on an old Application Note from National Semiconductor. According to the Application Notes, the following circuit was supposed to be high-performance, and has a high output-level (The schematics below is not the original one from the note, I've slightly adjusted component values to match the parts I own).

This is the actual build on a breadboard. I fully understand that breadboard is not suitable for circuits like this one, but it's just 4 MHz, so I didn't expect major issues (edit: the transistor has a typo, it should be labeled "CBE", not "BCE").

But it was disappointing, the circuit was not working properly. The output from the oscillator was too low. I was seeing a sine wave ~700 mV Pk-Pk, with a ~1.8 volts DC bias. Furthermore, it shows a very high output impedance, the signal would completely disappear if a load of 1000 ohm was connected.

I didn't record it, the following is not the actual waveform, but it's a bit similar to the non-working waveform.

But today, after a night of sleep. I removed my unsuccessful tweaks and restored the breadboard to the original circuit. And I found the oscillator suddenly starts to output a large 5 volt Pk-Pk signal. The output is so large that it distorts the sine wave.

I can't understand how it could have happened. Could anyone give a plausible explanation? Was it due to the variation of the parasitic capacitance? Was it due to a wrong connection made in the beginning (and the oscillation was still created due to the parasitic capacitance)? if so, what kind of mistake may produce the original result? Was it due to the temperature variation of resistor values or the hFE of the transistor? Or it was something else?

Secondly, how can I reduce the distortion of the sine wave? Can I increase the value of R3?

Thanks!


texts: ISP Programming pins of ATtiny25 multiplexed for other peripherals

texts:
We are using ATtiny25 IC micro controller interfaced with I2C based Capacitive Sensor IS31SE5104.

ATtiny25(U1) is programmed with (J1) ISP header (SPI pins used), ATtiny I2C pins are multiplexed with ISP pins as per datasheet and same pins planning to use for interfacing IS31SE5104 (U2).

Is it correct approach? Can we use same ATtiny pins for ISP as well as I2C based sensor IS31SE5104?

Please someone guide, Thanks in advance.


texts:
I've to switch on for a short time a series of 6 or 7 leds with a 24Vdc.
Follow some details...

power supply: 24VDC
led: 1W CREE XRE Q5  link

Power: 1W
Voltage: 3-3.7V
Current: 300-500mA

this small circuit with IRF520 mosfet

Camera GPIO configured as output as follow. I'd like to use this output to drive the mosfet

The IRF520 can be suitable in this case?

How to connect the camera output to the mosfet?

I have to put a resistor in series at led, how much ohm and power?

Thank you for your time.

Any advice will be very appreciated.


texts: How can one of the RC networks of this active high pass filter topology work as an actual high pass filter?

texts:
I have seen some previous vague questions related to a similar case but not for this topology.

The following circuit (source: http://stompville.co.uk/?p=470) shows an alternative topology for an active high pass filter. I have seen it in some instrumentaion literature as well, as a way of how to add some offset to the filtered signal.

Regarding the RC networks present in this circuit, I do not understand how the one composed by C2 and Rg can actually work as a high pass filter, since the capacitor is connected to ground - shouldn't it work as a low pass filter instead, as high frequencies would go through it? I have tried to analyze the circuit in order to understand this behaviour but I fail to find any answer. Is my understanding incorrect?


texts: What kind of building blocks are most transistors in current generation CPU's dedicated to?

texts:
When you look at the newest consumer AMD and Intel chips with billions of transistors, what the (Pareto) breakdown of building blocks used? Or asking in another way, if you zoomed into a modern CPU what would be the building-block type breakdown per unit area (from occupying most area to least)?

Of course Cache would be the Nr 1 but what about the next 9 or so?

Is there a document which lists those out (per transistor count or per unit area from most to least)?


texts: What are the side effects of having unwanted knots in a solenoid / enameled wire loop?

texts:
I've been winding a guitar pickup and occasionally there will be knots in the thread of enameled wire from my spool. Some of them are loose enough that I can untie them, but there are some really tight ones that if I were to try and pull the ends apart, the thread would break and I would have to start my process over.
My assumption is that, given that a pickup is usually a couple thousand feet of wire, that one or two few-inch knots in the loop are negligible - that they would add some unwanted resistance and/or leakage current(?) but wouldn't be enough to impede current from driving through the loop when the guitar strings are plucked. But I'm not actually sure.
What are the effects of having knots in a solenoid or wire loop?


texts: What are the relevant parameters for a reverse-biased LED light sensor?

texts:
Following this appnote (PDF) on using photodiodes, I'm connecting an IR LED as a light sensor and emitter, configured like this:

To emit light, I pull PIN1 high and PIN2 low; R2 serves as a current limiting resistor. To detect light, I pull PIN2 high and connect PIN1 to an ADC; U$1 and R1 form a voltage divider, and the voltage on PIN1 is proportional to the amount of light.

What I'm curious about is the best value for R1 and its relation to output voltage and response time. The appnote gives a formula for calculating the response time, but leaves terms undefined. The current value of 20M was based on experimentation with a breadboard; at this value it gives reasonable results between 0 and 0.15 volts for reflected light from another identical LED, and a bit over 5V if I point the emitting LED directly at the detector.

I'd like to increase the sensitivity to low light levels, but I don't know how much I can safely do so without sacrificing response time. My target component isn't the same as I was using on the breadboard, either, and I don't know what parameters of the LED affect the output voltage. In a nutshell:

How do I determine the response time of this circuit in its detecting configuration?
How can I determine what voltage level to expect at PIN1 with a given value of R1 and a given light level?


texts: register enable line usage in `case` block (verilog synthesis for altera cpld)

texts:
I have the following in a verilog design aimed at an altera CPLD (currently targeting EPM240, although the target device isn't set in stone):

always @(posedge clk)
    if (we)
    begin
        case (rw_sel)
           3'd0: reg0 <= data_in;
           3'd1: reg1 <= data_in;
           ...
        endcase
    end

I assumed that this would synthesize a design where rw_sel was decoded into a number of different select lines, which would be 'and'ed with we, and then connected to the enable input of the register.

However, this isn't what has been done: examining the results in the RTL viewer, the we line has been connected directly to the enable inputs of every register, then the data input of each register is connected to a mux2 that selects from either the incoming data or the current value of the register.

Isn't this much less space-efficient than the design I was expecting?  And if so, how can I persuade Quartus to generate the more efficient version?


texts: Understanding this statement in ATmega328P's datasheet

texts:
While reading ATmega328P's datasheet, I came across the following statement.

  The Port X output buffers have symmetrical drive characteristics with both high sink and source capability.

What does that statement mean?


texts:
This question is specifically targeted to a RTOS -- ThreadX.

We are using it for our project. Problem with this is default RTOS tick time is 10ms which is very high. We need to change it to 1ms.

Has anyone used this RTOS?

(For Ref:ThreadX PPT


texts: Grounding GPIO pins during 8051 programming

texts:
I'm trying to make a programmer for the 8051 microcontroller IC's, specifically the AT89C2051. I saw a circuit online (the blowit programmer) in which the unused GPIO pins are left floating.

When the 8051 is in normal execution mode, the outputs are always high-impedance or grounded, and applying external ground never hurts the IC, but applying external VCC causes the IC to not operate correctly if I set a logic low on the same GPIO pin in software.

I checked the datasheet and it does not mention anything about the state of the pins that are not used when programming the IC.

I'm curious. For this IC or any other 8051 based IC, is it a problem if I ground all unused GPIO pins during programming?

I also think if I can do that, then a side benefit would be less noise, but then again I'm not sure if that benefit applies because each GPIO pin has an internal pull-up resistor.


texts: How can I construct 2:4 Decoder circuit with the help of IC74139 (74xx139)

texts:
This is the Truth Table for IC74139 (74xx139) that 2:4 Decoder:

I just know to construct 1:4 decoder only. And when I build my circuit, it cannot meet the accuracy of that truth table...
Can you help me to construct that circuit please?
(Note: I've built it wrongly and to correct my false circuit, you can check my wrong diagram below)

( I did it with "circuitverse" simulation website)


texts: Where to get/How to make a potentiometer with "clicking" steps?

texts:
Maybe you remember that very old (and sturdy!!!) electrical panels/machines had those big knobs that you could turn to fixed positions (steps) with a very unique clicking sound. I need to make one or get something similar so the potentiometer in my design stays on one of the 10 predefined positions.

Could you point me in the right direction? Maybe those kind of knobs have a specific name? Maybe even the pots themselves are special...


texts: How to Calculate the average of a Square Wave?

texts:
I could not figure how to calculate the average of a square wave.

Consider a square wave of +5V from time 0 to 6 sec and -3V from 6 to 10 sec.

On integrating from time 0 to 6 the average: 3.0V

On integrating from time 6 to 10 the average: -1.2V

Thus the total average is : $$3-1.2=1.8V$$

But according to my teacher it results in 4.2V (3 +1.2).

Can anyone explain me the calculation?


texts:
The bias point (without the 623mv input) is calculated as
\$I_b = \frac{5-0.6}{5.5 M\Omega} = 800nA\$
\$Ic = \beta I_b = 290*800nA = 233\mu A\$
These calculations checks out in the simulator.
But when I connect, the Input signal, whose peek is at 623mV, the transistor saturates. Why?
Because, if I do the calculations again with \$V_{BE} = 0.62318V\$, the results do not change much from the previous calculation.
\$I_b = 795.78nA \$ which should give the \$I_c = \beta I_b = 290*795.78nA = 230.8 \mu A\$, and this is \$ << I_C(sat)\$. Then why is the transistor saturated?
I know the transister is saturated because the \$V_{CE} = 67.4mV\$, when it should have been
\$5 - (230.8\mu A * 10k) = 2.7V\$


texts:
I am trying to use a N-Channel Power MOSFET to turn on a capacitor bank in my MRI birdcage coil. I tried using PIN diodes as a switch but they kept failing as they could not handle 400 V and 9 A that goes through the coil. I came across a paper which describes this circuit:

Here they use two MOSFETs back to back in order to avoid the bypass of a single MOSFET in the OFF-state by its drain-source body diode during the half-cycles when VD < VS.
I took two IRF540 MOSFETs, connected them as shown in the circuit. The input was connected to a signal generator putting out a sine wave at 2.5 MHz and 1 Vpp. The output was connected to an oscilloscope. I tied both the gates together and used 4.5 VDC as my control voltage.

However, when I power the MOSFET and turn it on with Vgs = 4.5 V, the output is distorted and the output is present  even when Vgs is 0.
Can someone help me understand what is wrong with this setup? Is the setup itself flawed or are MOSFETs a bad way to switch RF?

I am essentially trying to replace the diode D1 in the circuit below:

A would be the input and B would be the output. B is also where I send a 5 V control signal to turn on the diode. The PIN diodes that were being used for D1 were breaking constantly and I want to come up with a better solution. The input is from a pulsed RF amplifier putting out 4000V to a coil matched at 50 Ohms.

It would be great if someone can help me out with this. Thank you.


texts:
Recently I bought a 128x240 LCD with ts6963c driver chip. The part number is TS240128D-1. I am familiar with KS0108 driver but the problem is different pinouts.
I found a good manual in a book for ts6963c and expected a 19 pins module but the module contains 22 pins.Here is the data sheet:TS240128D-1

I dont know what the pins "pin4: VO" , "pin19: VOUT" doing there. Are they connected with a potentiometer to each other and ground as is in ks0108?
On the other hand, in page 2 of that data sheet, pin 22 is named "DSPON" (Display ON?) but in top of the next page it is named "NC" (Not Connected?). What is this pin doing?
It would be a great help if anyone can answer my question.


texts: Accidentally used 3.6 volt battery for my mouse, now it only works with 3.6 volt

texts:
My mouse requires AA 1.5 volt batteries to work. I accidentally used a 3.6 volt Li-SOCl2 battery. Now it works fine with the 3.6 volt battery but doesn't work at all with a 1.5 volt AA battery.

I have this mouse and keyboard combi:
https://www.microsoft.com/accessories/en-nz/products/keyboards/sculpt-ergonomic-desktop/l5v-00027

How is this even possible?

Perhaps some traces are burnt enough so that no current can flow through them with 1.5 volt?


texts: How to select the right MOSFET for a LiPo battery protection circuit

texts: I want to build a LiPo protection circuit for my quadcopter where MOSFETs are connected to the primary and secondary battery. When the voltage falls below certain value in the primary battery the voltage monitor triggers the P channel MOSFET and cut the supply from primary and simultaneously the N channel MOSFET connected to the secondary battery turns ON and supplies the power. Batteries are rated 22 V Max current is 250 A.


texts: Appropriate fuse for 12V battery - solar power controller connection

texts: I'm a biologist tracking migratory bats and need to build a bunch of antenna towers to listen for pulses from tagged bats flying nearby.  These are off-grid, so we'll have 55W solar panels charging 12V 100Ah deep cycle batteries during the day, and the sensor gnomes use that battery power to listen for bats at night.  I need to put a fuse between the battery and the solar controller.  The first version of this system used 20A class CC fuses and a bulky fuse box meant for home solar use.  Is there any reason I can't use a smaller and cheaper fuse and box, perhaps an in-line model made for car batteries? The controller is the Morningstar Sunsaver SS-6L-12V if that matters.  Let me know if you need more information.  Thanks!


texts:
With refer to this question:
I got CTs connected to all analog pins on a Arduino Mega, connections for each pins are as mentioned here.
Readings were good indoors, +- 0.1A. However, when located outdoors, even without connecting any CTs/ connected to a CT(but the CT is not clamped onto any wires), readings are detected, ranging from 0.1A to 2A.
I am using a CT for 50A range measurement and the output signal is 1Vac.
The IOREF pin is linked to the Vin pin on the Arduino board.

I have tried to make more accurate readings (hoping to achieve at least +-0.1A) from programming as in here, and here. Doesn't make much difference though...

I have used a non-polarized capacitor in my circuit. I was thinking if that cause the noise? But I thought polarized/non-polarized capacitor does not matter in this case?

Would a ferrite bead on the CT be helpful? Or in other terms, the connecting wires needed to be shielded? The wires are only for transmitting a voltage back to the analog pins, how could noise enter the wire?

Lastly, I actually got the circuit on a pcb. The grid are 0.5mm. So...poor PCB design? i.e. traces too close to each other?