texts: Finding the average power dissipated in a resistor

texts:
Well, I've a series RL circuit that is powered by a voltage source. The input voltage is given by:

$$\text{V}_{\text{in}}\left(t\right)=50+\frac{400}{\pi}\cdot\sum_{\text{n}=1}^\infty\frac{\sin\left(200\pi\cdot\text{n}\cdot t\right)}{\text{n}}\tag1$$

The resistor value is equal to \$\text{R}=20\space\Omega\$ and the inductor value is equal to \$\text{L}
=25\cdot10^{-3}\space\text{H}\$.

  Question: I've to find the average power that is dissipated in the resistor.

My work:

We can write for the power dissipated in the resistor, using Ohm's law, that:

$$\text{P}_\text{R}\left(t\right)=\text{V}_\text{R}\left(t\right)\cdot\text{I}_\text{R}\left(t\right)=\text{I}_\text{R}^2\left(t\right)\cdot\text{R}\tag2$$

Where \$\text{I}_\text{R}\left(t\right)\$ is the current trough the resistor and \$\text{V}_\text{R}\left(t\right)\$ is the voltage across the resistor.

Because it is a series circuit, the input current, \$\text{I}_\text{in}\left(t\right)\$, delivered by the source is the same trough the resistor and the inductor, so \$\text{I}_\text{R}\left(t\right)=\text{I}_\text{in}\left(t\right)=\text{I}_\text{L}\left(t\right)\$. Using Faraday's law, we can find that input current:

$$-\text{V}_\text{in}\left(t\right)+\text{I}_\text{in}\left(t\right)\cdot\text{R}=-\text{I}_\text{in}'\left(t\right)\cdot\text{L}\tag3$$

The initial condition is equal to \$0\$, so we know that \$\text{I}_\text{in}\left(0\right)=0\$. Now we need to solve equation \$(3)\$ using the values that are given.

Solving equation \$(3)\$ gives:

$$\text{I}_\text{in}\left(t\right)=\frac{1}{\text{L}}\cdot\exp\left(-\frac{\text{R}}{\text{L}}\cdot t\right)\cdot\left\{\int_1^t\text{X}\left(\tau\right)\space\text{d}\tau-\int_1^0\text{X}\left(\tau\right)\space\text{d}\tau\right\}\tag4$$

Where \$\text{X}\left(\tau\right)=\exp\left(\frac{\text{R}}{\text{L}}\cdot\tau\right)\cdot\text{V}_\text{in}\left(\tau\right)\$.

The average power that is dissipated in the resistor is equal to:

$$\overline{\text{P}}_\text{R}=\lim_{\text{n}\to\infty}\frac{1}{\text{n}}\cdot\int_0^\text{n}\text{P}_\text{R}\left(t\right)\space\text{d}t=\lim_{\text{n}\to\infty}\frac{1}{\text{n}}\cdot\int_0^\text{n}\text{I}_\text{R}^2\left(t\right)\cdot\text{R}\space\text{d}t=$$
$$\text{R}\cdot\left\{\lim_{\text{n}\to\infty}\frac{1}{\text{n}}\cdot\int_0^\text{n}\text{I}_\text{in}^2\left(t\right)\space\text{d}t\right\}\tag5$$

Now, the input current \$\text{I}_\text{in}\left(t\right)\$ that is stated in the integral at the end of equation \$(5)\$ can be found using the solution to the DE given in equation \$(4)$.

  Question: How can I solve the integral given in equation \$(5)\$, that is the part where I do not get my head around?

EDIT:

I already found that, using the given values that:

$$\int_1^0\text{X}\left(t\right)\space\text{d}\tau=\frac{3}{8}\cdot\left(1-e^{800}\right)\tag6$$

And:

$$\frac{1}{\text{L}}\cdot\exp\left(-\frac{\text{R}}{\text{L}}\cdot t\right)=40e^{-800t}\tag7$$

And:

$$\int_1^t\text{X}\left(\tau\right)\space\text{d}\tau=\int_1^t\exp\left(\frac{\text{R}}{\text{L}}\cdot\tau\right)\cdot\left\{50+\frac{400}{\pi}\cdot\sum_{\text{n}=1}^\infty\frac{\sin\left(200\pi\cdot\text{n}\cdot\tau\right)}{\text{n}}\right\}\space\text{d}\tau=$$
$$\int_1^t\exp\left(\frac{\text{R}}{\text{L}}\cdot\tau\right)\cdot50\space\text{d}\tau+\int_1^t\exp\left(\frac{\text{R}}{\text{L}}\cdot\tau\right)\cdot\frac{400}{\pi}\cdot\sum_{\text{n}=1}^\infty\frac{\sin\left(200\pi\cdot\text{n}\cdot\tau\right)}{\text{n}}\space\text{d}\tau=$$
$$\frac{e^{800t}-e^{800}}{16}+\frac{400}{\pi}\cdot\sum_{\text{n}=1}^\infty\frac{1}{\text{n}}\cdot\left\{\int_1^t\exp\left(800\cdot\tau\right)\cdot\sin\left(200\pi\cdot\text{n}\cdot\tau\right)\space\text{d}\tau\right\}\tag8$$


texts:
I am using a PIC 18F46J50 microcontroller and the C18 compiler.

I want to retain some data when the controller exits deep sleep mode.  I found two registers DSGPR0 and DSGPR1 for context saving but it seems only two bytes are available there.

If I wanted to save more bytes, what are my options?

I would welcome suggestions that are possible with the 8 bit PIC family.


texts:
I am analyzing a large circuit and I want to perform an unpowered analog test simulation of the circuit (as it is a large schematic, i have divided it into various modules/pages). My aim is to do a pre-calculation or a simulation of an unpowered analog test of this circuit before an In-circuit test (ICT) in series production.

One of the modules looks like the below schematic.  With a simulation, I want to know, if all components in circuit are present and the values of the components are correct.

For this modeule, I have only 2 test points for this particular sensor Module, TP_100 and TP_200 availble during the testing in series production. One test point (say TP_100) has influence from the other components in the same network which is near to the other test point (say TP_200).

But I dont have an idea, How to perform a simulation or pre-calculation for an In-Circuit Test?

edit: It is meant for an unpowered analog test, not an EOL test to check the functionality of the circuit, but to check the value of individual component or cluster of components.


texts: Ultra low power configuration for a microcontroller switch?

texts:
I have a project that is very low power (>10uA idle), and I'd like to have a reed switch input to give me a digital indication of a certain system state.

I can't guarantee which state the switch will be in for the majority of the time, so what is the lowest power way to implement a switch in this case? Ideally it would draw less than 1uA on average.

If possible I'd like to use one pin on the microcontroller since GPIO is limited.


texts: Can 12v destroy a laptop instead of 11.1v

texts: I am making some experiment on the 18650 battery, I learnt that their charging voltage is 4.2v while nominal voltage is 3.7v. I made a 2ways parallel connect of 3 serial connection just like the laptop battery pack, on the laptop 11.1v is written which is 3 x 3.7v but I charge the battery with a 12.5v charger which is still with the charging range of the cell 4.20v * 3=12.6 and the battery is now charge to 12.3v and started getting warm so I disconnected it even despite that its not yet up charge to my charger range. But the problem is that I dont know if 12.3v would damage the laptop if I connect to the battery port with the circuit since they wrote 11.1v, and i would like to know what that nominal voltage mean and I would to know maybe if I increase the battery cells from 6 to maybe 9 or 12 in other to increase the amp/h would it damage my battery. If would be very greatly for your help


texts: What is the highest practical value for DC voltage divider

texts:
I am using a high side load MOSFET switching circuit as a low current voltage divider. I am trying to minimize the current from the battery V1.

How do I determine what is the highest practical value of R2, R3, and R4 can be? Can I use Megahoms values?
This is for DC measurement and the output Vdiv goes to microcontroller ADC. Also, would it help to have a buffer going to the ADC?

Thanks


texts:
OK, DILs are on the way out, but from time to time you still can see CMOS DILs packaged like this as ESD protection:

That's aluminium foil on EPS (expanded polystyrene). The EPS isn't conductive, but the aluminium foil is supposed to short the pins. Is this a reliable way to store CMOS components?


texts:
I am currently building a quad-copter out of an Arduino. I decided to make my own ESCs using MOSFETs, EMF sensors, and the Arduino. These are the motors that will be driven: http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=6247&aff=61689; This is the 11.1v LiPo: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8934&aff=61689; I understand the basic principals of an ESC's operation, but I still have a few questions that I could not find the answers to:

Will I need any form of current and/or voltage limiting components?
Will the motors burn out with 18+ Amps running through?
Will the enamel on the coil windings burn off?

Thanks.


texts: SPI routing question...Maximum length SPI can be routed

texts:
Basically my question is regarding maximum length of SPI routing, and route efficiently in my scenario and any timing issues(Setup and Hold).

I am just explaining my scenario. Please bear with me, it is very big message...

I have an EVK which has SPI exposed to a 10-pin connector, and I have slave board (RF board) which has SPI exposed to 20-pin connector.they can't be directly connected, that's why I am designing a 10-pin to 20-pin interfacing board to interface effectively.

Unfortunately because of mechanical constraints, i need to use a flex cable to route between 10-pin Connector on EVK to 20-pin interfacing board. Slave board directly mates to 20-pin connector of interfacing board.

I am running SPI at max 8Mhz with 4-20nS Rise times.

I don't have any control on Slave board and EVK side. Only i have control on 10-pin to 20-pin interfacing board.

I want to know what is the maximum length of flex cable can used between EVK and interfacing board.

What things can be done to mitigate SI problems and ensure signal quality. Is there any free tool (I have altium using which i am not able to simulate) to simulate this scenario.
Is there any timing issues that need to be taken care of here.*

I want more of a quantitative explanation.


texts: Understanding power dissapation of MOSFET's

texts: I'm currently trying to understand how MOSFET's work in total but come across confusing information when looking into power dissipation of the mosfet; mainly how to calculate it. Say I have a circuit that will consume 5A at 3.5V how would I go about calculating the power dissipation required for the MOSFET? Would I simply just do P=IA; and need a MOSFET capable of 17.5W of power dissipation? Or is more at play here?


texts:
I live in a New York apt and I woke up last Saturday (5/30/15) because our power went out at about 7:30 am. A quick check with the bldg's doorman revealed that it was just our apt and not a total blackout as I first thought it was. Our maintenance guy came and checked our circuit breaker using a simple power tester. He seemed to know what the problem was and proceeded to explain that we have a negative feed problem. When I asked him what a negative feed was he tried to explain it this way: "In an old apartment, sometimes one of the 2 live wires 'dies' and when that happens your appliances consumes power even when they are turned off. And that's what's called a negative feed. He also said something about 1 of wires as positive and the other, negative." He then said that he can revive the dead wire by putting a device. The whole thing will probably cost us a thousand but he can do it for $250. He also said that the same situation happened to one of the tenants in the building a week ago.

His explanation was vague and theory-wise, I've never heard of such a thing. I'm a graduate of electronics and communication eng'g back in 1982 in my home country. While I know much has changed and I haven't put what I learned into practice, his explanation was highly suspicious and I immediately thought that I'm being scammed.

Am I? Thanks in advance.

Horace


texts: Non Coherent Detection of Digital Signal

texts:
I am trying to design my first wireless digital communication system. I am going to use non-coherent procedure for detection.

Say I am sending a particular bit $$T_b=5secs$$

Now at transmitting side I start the bit time from some particular (may be arbitrary) reference time. But at the receiving side from when to start measuring this particular bit. As my system is non-coherent, I have no clue when to start the bit measuring process. The book does not say much on that.

Any clue would be greatly appreciated.


texts: Push-pull transistor - input current spikes and advantage over just an npn transistor

texts:
I have simulated the following circuitry in LTSpice:

Input Voltage pulse characteristics:

Questions:
1. What is the reason for the current spikes on the input resistor R2? Do I need to worry about this?

This is the corresponding current output on R1:

When driving an nchannel mosfet, my understanding is I need to use a push-pull transistor pair to be able to feed in more current to the mosfet to overcome its gate capacitance. But, in simulation, when I use just an npn transistor, the current output is the same as the push-pull pair. Is my circuit wrong?


texts:
let me begin by thanking anyone and everyone for any help.

I have a serious lighting project and am likely getting very ambitious.

I am trying to wire up a series of WS2812 LED strips.  Each 2 strips of 24 LEDs will be contained in a box, so 48 RGB LEDs per box (think 2 rows per box).  I will ultimately have ~48 boxes, so over 2300 LEDs.  I want to wire these as simply as possible.  There is a Power, Ground, and Data.  Data is directional.  I figure to avoid voltage drops I have to bring power in every third box or so.  I am told each LED pulls 20 mAmps and there are 3 LEDs per WS2812 (R,G,& B).  So in reality each of the 48 LEDs is really 3x, which equals 144 per box.  Thus 60mAmps per RGB LED or 2880 mAmps per box, if my math is correct. Oh, and these are the 5V variety of LEDs.

Here are my questions:

What gauge wire could I use?  Would quality Phone line or Cat 5/6 work if I get a 22 gauge version?
Could I use those connectors?  Phone/Cat5/6 or are we talking too much power?
Could I daisy chain the data or would this cause problems?  Do I need to run data out to a junction box?
Is there any easy way to connect or bring things back to power the the brain running all these lights?  Was thinking of a Teensy 3.1 to control everything.

Any advise would be appreciated.  This will be for public displays and I want to keep EVERYONE, me included, safe around these lights.

update:

Was planning on implementing in stages. Have 30 m of the LED strips at the moment and that will let me make ~25 of the boxes. Yes I know that is still a lot, but can wire up a couple of them at a time and test everything. This is why I am wanting to dot the i and cross the t.

If I read the amperage table correctly 22 gauge wire would support 7 amps. So I still have almost double the capacity. Thanks for the catch on the controller.

Any idea on those connectors?

update:

At the moment I have a 60Amp power supply. Could get more of these or something larger. Haven't figured that out yet.


texts: How to view Center-Aligned PWM on an Oscilloscope

texts: I wonder how can I identify if I see a PWM waveform on an oscilloscope screen whether it is an edge-aligned or a center-aligned PWM waveform. Can anyone help me how to do that?


texts: Creating an opto isolator board for Raspberry Pi

texts:
I have a relay board which I bought from dx.com and I am not sure about its reliability. If it fails, then it may harm my Pi right? So I googled around and read that opto isolator provide complete isolation. Even though the relay board is built with an opto isolator, still I won't trust it.

I chose PIC 817 for this. There is no strong reason behind it. I found its datascheme here. From what I understand, for operating input should be 1.2v 20mA.

The relay requires 5v to turn on/off and 5v to operate the relay board.

Based on this I made following circuit and I calculated R1 using Ohm's law.

(3.3v - 1.2v)/0.02A = 105 Ohms

I also want to power the relay from Pi itself. I think I should keep a diode in between them so that its always unidirectional and there is no current coming from relay board to Pi. And I think diode with minimum 5v should do for this purpose. I picked 1N4007 because it's easily available for me. It's ratings are 1000v and 1A. Or should I be using a transistor instead?

Is following circuit correct? Do I need to any extra component? and also can this whole thing can be replaced by any available IC?

simulate this circuit – Schematic created using CircuitLab


texts:
How  can i test if a sensor is working ?
It's a sensor for the refrigerator.
(sensor's specs:

1TW metalflex Tv 433.c 2/250 tf72°c
)
```


texts: Options for soldering a through hole PCB (e.g. Teensy) flush/flat on another PCB

texts:
I am looking to incorporate a Teensy board on my PCB. I want to solder the Teensy PCB onto my PCB. But I also want to minimize the height above my PCB as much as possible. Hence, I DO NOT want to solder using regular header pins -- i.e. I DONT want this:

I want the Teensy to sit as flush as possible on my PCB. Unfortunately, the Teensy does not come with castellated holes (like the Photon or most wireless boards):

So I was thinking of the following options:

Using low profile header pins like this one -- https://www.pololu.com/product/2663 (plastic height is 1.5mm instead of usual 2.5mm). But I want to avoid the 1.5mm as well
Use straight pins like this - http://www.digikey.com/product-search/en?mpart=3560-2-00-15-00-00-03-0&vendor=54 -- and soldering the Teensy flat on my PCB. Is this a viable option?? A google search doesnt really show me examples of this being done.

What other tricks/tips can I use??

(I understand that the best way is to not use the Teensy board directly, and instead to design the Teensy ckt on my PCB. But for some reasons I do not want to get into that right now.)


texts: Microprogramming vs. Machine Language programming

texts:
I'm a bit confused between the microprogramming level vs machine language level.  For example:

Where do both types of programs reside while being executed?
Do either have a 1:1 mapping to assembly language true-op instructions?
Is the format of either defined by the processor architecture?


texts: How can I link battery life to resistivity of a phone PCB?

texts:
Are there any equations/relevant explanations that can link resistivity of the "wiring"* (or other components) on a phone's PCB to its battery life, i.e. can I prove that using silver wires would extend battery life compared to copper wires, and by how much?

*I know its not actual wires, but I have no idea what the metal line things are called.


texts: Need help on 2N3055 12v DC to 220v AC Inverter Circuit

texts:
I am about to build a 12V DC to 220V AC inverter using power transistor 2N3055.
I am following this circuit diagram.

The transformer is 220V to 12V step down (12-0-12) 4 Amp transformer. And the battery is 12V 7 Ah Lead Acid battery.

First of all - the circuit doesn't work on Simulator. However, I found several blogs claiming that the circuit is valid and works. Could you please let me know why it doesn't work on simulators?
And secondly, are the values of R1 - R4 correct in order to allow 2N3055 to oscillate? I am planning to use all the 4 resistances 10Watt rated.


texts: Voltage follower with thermal protection

texts:
Could someone suggest a voltage follower with thermal protection (thermal shutdown)?

I see possible solutions:

An LDO with external reference. I found only few of them, seems they are called tracking LDO and they are very rare and are hard to buy. Maybe I did a wrong search?
Use a transistor with thermal shutdown. I found only one transistor in the entire internet and it's seem obsolete. Does such transistors exist?
High current op-amp with thermal shutdown. I found only big expensive specialized devices of this type. Are there small, like SOT-23-6, and cheap op-amps of this type?
Maybe it's possible to create a voltage follower using an op-amp and a regular adjustable LDO? How?
Something else?

Please share your ideas. Thank you.

Just if you want a specific details: I need a voltage follower buffering 1.2-3.3V signal and powered from 5V supply. I want it to be able to provide up to 200mA of current at least for short period of time, typical consumption is about 30-50mA. Since my device is small and fitted in 10 x 8 x 3cm plastic box, I think, there is a possibility that under long lasting worst condition (200mA at 1.2V (i.e. 3.8V dropout)) the transistor of classic voltage follower could overheat. That is why I would like to have a solution with thermal shutdown.


texts: How do you correlate voltage output with these values that I have collected?

texts:
I'm using a "Logomatic v2 Serial SD Datalogger" to measure the voltage output of this piezo-resistive sensor, "Force Sensitive Resistor - Square." The values are logged in a .txt file in a microSD. (I would link the datasheets and such to both of them, but I cannot post more than two links. Google should direct you to them).

I configured it first to ASCII ADC mode (mode 2, ASCII = Y) and I got this log file. I also configured it to binary ADC mode (mode 2, ASCII = N) and I got this weird file.

However, I'm not sure how to analyze the values in the log. How do I translate these values to a certain voltage output? I ultimately want to correlate a certain voltage output or resistance with the amount of pressure being exerted upon the sensor.

As for my circuit, I'm supplying 3.3V to the sensor, connected the sensor to a ADC port of the data logger, added a voltage divider (resistor) between power and GND.


texts: I want to make a photo-trap for wildlife

texts:
I want to make a photo-trap with extra features.

I tried using a Raspberry Pi for this, but I could not start the system in under 4 seconds.

When other photo-traps detect motion, they start recording in less than 1 second. They also offer up to 6 months of battery life.

I want to make a device similar to this, but it will send me a data from some sensors over wireless. The products on the market do not do that.

In summary, I need a processor or device that can be started in less than 1 second, suitable for battery use, and where I can record HD and configure its software.

I would like to receive suggestions and ideas from people knowledgeable about this subject.

Edit:
I turned off everything possible in raspberry pi. I also open the system with a processor and sensor group, but the raspberry pi cannot open before 5 seconds. This is too late for what I want to catch. Of course, how can the photo-traps sold in the market open up to 200-300ms with a 6-month battery life and start recording?


texts: What is the Vout of 74154 demux and 7404 hex inverter?

texts:
I've read through the datasheet of 74154 and have seen that its Vout ranges from 0.5V to Vcc+0.5V. So if the Vcc is 5V, I am assuming I can get 5.5V max Vout in the output pins. However, a friend of mine said that since 74154 is TTL, its Vout is about 2.5V to 3.5V; tho she did not mention if this is during ACTIVE HIGH or ACTIVE LOW.

My question being: in practice, how much really is the Vout of a 74154 demux during its ACTIVE LOW and during its ACTIVE HIGH at one output instance (say, with an 0000 input that gives an output of ACTIVE LOW at pin 1 and ACTIVE HIGH at all other pins)?

I have the same question as per the 7404 IC.

Can someone help? :) Thank you!


texts: Single supply op-amp circuit not working like in simulation

texts:
I have this circuit that amplifies an electric guitar signal of -1.5 to 1.5 V to 0 to 3 V.

The circuit worked perfectly in my Multisim simulation, but the signal doesn't change with the input it only stays at 3.3 Vs. The only thing I'm doing different from the the circuit above is I'm using two op amps on the same chip(MCP6002). I tried using a decoupling capacitor on first positive input, but I had the same problem.


texts: Need help with little assembly language code

texts:
Can anyone help me convert the below assembly language code to Arduino (Embedded C) code. I'm trying to program ATTiny24 as an SPI slave to establish communication between it and Arduino NANO (master).
init:
       ldi r16,(1<<USIWM0)|(1<<USICS1)
       out USICR,r16
...
SlaveSPITransfer:
                    out USIDR,r16
                    ldi r16,(1<<USIOIF)
                    out USISR,r16
SlaveSPITransfer_loop:
                    in r16, USISR
                    sbrs r16, USIOIF               //sbrs - skip if bit in register is set
                    rjmp SlaveSPITransfer_loop    //relative jump
                    in r16,USIDR
                    ret

I've only figured that the initialization part is written as:
USICR = USICR | (1<<USIWM0)|(1<<USICS1);

Any help will be appreciated.


texts: Bus Contention - Output Pin driving another Output Pin

texts:
I've run into an unusual problem. I'll start off by describing my goal: I'm designing a circuit that can test for short circuits and open circuits in a wiring harness. The wiring harness does not have a CAN bus or anything complicated like that - just simple wires.

Here's how it works

I have two CPLDs, one as a designated driving end (all pins are output) and another as an receiving end (all pins are input). The driving end CPLD is programmed to be a Serial In Parallel Out shift register and the receiving end is a Parallel In Serial Out shift register.

Let's assume all the wires in the harness are one-to-one i.e. no junctions. Let's also assume that there are only 8 wires. So, to test the first wire in the harness, the driving end register is loaded with 10000000. The receiving end also sees this and it all ends well. The driving end is then clocked and it reads 01000000. If the receiver also reads this, then that wire is OK.

But suppose there is a short circuit between wire 2 and 3. If that's the case, then the receiving end will read 01100000. This, too, is OK as we have detected the short and can take action.

But what happens at the driving end? The CPLD's pin 3 will be forcing 0V and pin 2 will be forcing 3.3V. The short circuit between pin 2 and 3 will result in two output pins connected together. I'm assume that a significant current will flow from pin 2 to pin 3 and damage could result.

Note that the shift registers/CPLDs are being driven by a microcontroller. Also note that the harness is usually quite large, around 200-300 wires. Some of which are one-to-many connections. This is why a CPLD was an attractive option as it allows me to program a large shift register and allows testing of a large harness with a relatively small circuit.

How can I handle such a problem?


texts: reading a high negative voltage with attinys running on batteries

texts:
I need to read a negative input voltage from a camera flash capacitor that can charge up to -330V. I am using an attiny85V that is running on batteries and want to set the internal reference voltage to 1.1V for the ADC. My idea is to use the circuit below to map the flash capacitor voltage to the 0-1V range for the attiny by using a resistive level shifter and a zener diode to create a voltage reference for the resistive level shifter.

Is this possible? And how do I choose the R6 resistor, one criteria is that it needs to be low enough to ensure that the Zener reverse-bias current (Iz) falls within an acceptable range, but do I also need to take R10 into account to make sure that the zenor diode does not sink current from the analog input pin? What else do I need to watch out for?

An error in the reading of the capacitor voltage of +-20V would be acceptable. I only need to know when the flash is charged enough to trigger.

note: the 1.0V reference voltage marking in the circuit is not connected to anything but rather for clarification.

here are the references I gathered my idea from:

explaination of zener diodes as voltage reference

measuring negative dc voltage


texts: How to uniquely identify which PCB is plugged in / connected

texts:
I am designing a board (Main PCB) into which any one of about 60 slightly different boards (Peripheral PCB) may be connected/plugged-in.

The challenge I'm facing is to autonomously identify which of the Peripheral boards is plugged in at any given time.

The Main PCB has a microcontroller available to do some processing.
However, to minimize part count, the Peripheral PCBs each have only a (unique) sensor, and no intelligence -- i.e., no microcontroller on board, e.g., to send information via digital pins or I2C -- as of now .
Both boards are open to design changes, although the inter-connector pin count leaves me at the moment with only two more free pins available to use for any further modification.

What is the simplest, least expensive way (< $1 USD) I can modify the circuits to let the Main PCB identify which of the Peripheral PCBs is plugged in?

Will I have to add a microcontroller to each Peripheral PCB, or is there a smarter way?

ADC reading of a unique voltage divider on each Peripheral board seemed like a good start but for such a large number of different boards to be identified, this does not seem like a very reliable strategy.


texts:
I have two electronics textbooks and for some reason, both of them just gloss over configurations that are not "Common Emitter".
Regarding the emitter follower, I understand that there's no voltage gain. It was very easy to see why. But then the author just says, it has a very high current gain. Even though he didn't bother to show why, I went on to calculate the ratio and indeed there was a large current gain. The problem is my mind is tuned to "Common Emitter" circuits where the base current is multiplied by beta. This current is large and so the output voltage is large. Hence the voltage gain. That is quite understood.
But when it comes to the emitter follower, where is the current "hiding" because I read that it can supply loads that require large current. I know I'm confusing things. That's why I am asking for an explanation.Thanks.


texts:
I'm trying to design a circuit that will power my 12V LEDs.  The battery should be 12V and up to 14V when charging.  I would like to route it through an LDO voltage regulator when the battery is charging and just pass through the battery directly to the LEDs when it's below 13V (as the LDO won't operate below 13V).

I looked at buck boost converters and couldn't find anything that looked helpful, and I didn't want to waste the power in doing a boost then buck converter.  Is this schematic feasible?  Below 13V, the JFET just stays on and passes power to the LEDs.  13V or more, the zener diode allows power to the LDO, which then passes 12V or so to the N-Channel JFET gate, turning off the JFET.

EDIT: I see that my poor schematic software is causing a lot of confusion.  Fritzring does not have the parts I was trying to render.  I am NOT using an LD33, but rather a typical 12V out, 2Amp load LDO voltage regulator.  Here's the datasheet for the KA278R12C: http://www.mouser.com/ds/2/308/KA278R12C-1120707.pdf.  This is not for a vehicle, but rather some indoor lighting hooked up to a battery.


texts: Can single conducting straight wire can radiate EM wave or we need two bend conducting wire similar to dipole antenna?

texts: Actually I have read somewhere that there is no radiation if wire is straight. If it is true then why people are explaining antenna radiation with straight wire diagram?


texts:
SN74HCT245 is a OCTAL BUS TRANSCEIVERS WITH 3-STATE OUTPUTS.

But i am not getting why we need it?

It basically transfers signal from port A to B or vice versa or isolate it.

Where we use it? Is it used as EPROM?


texts: Calculate radiation power of an antenna in respect to a given antenna radiation pattern and a given angle

texts:
I work on a program that simulates the wave propagation of high frequency electromagnetic waves (2.4 or 5 GHz Bands) in 3D. I use a ray launching approach, where the emitted rays approximate the electromagnetic waves, which carry the transmission power of a particular wave in dBm as an attribute. The user is able to import a csv list which holds the angles of the vertical and horizontal radiation pattern (polar diagram) and the corresponding values for the actual transmitted power from the antenna in dBm.

My question is now, how can I calculate the values in that list in respect to a given radiation pattern of an antenna? Or in other words, how can I calculate the real transmitted power of an antenna in respect to a given radiation pattern in the horizontal and vertical planes?

Thanks in advance and sorry for the bad English.

Update 1

The picture below shows an example for a radiation pattern that I want to use. With this pattern and the transmitting power of the transmitting antenna (In the case of 2.4 GHz Wireless LAN thats 20 dBm respectively 100 mW) I want to calculate the real outgoing power of the antenna in respect to the given angles (λ or φ) shown in the radiation pattern.

So my calculation would look something like this(?):

Poutgoing = 20 dBm * PdirectionDependentGainFactor(λ)

source: http://www.mpantenna.com/antenna-gain-and-radiation-patterns/


texts: Need help deriving cutoff frequency of output (collector) RC network

texts:
According to the book I'm studying, the cutoff frequency for this circuit

is given by
$$f_c=\frac{1}{2\pi(R_C+R_L)C_3}.$$

I tried to derive it by solving for the frequency at which \$V_{out}\$ is \$V_{collector}/\sqrt{2}\$:
$$\frac{V_{collector}R_L}{\sqrt{(R_C+R_L)^2+(\frac{1}{2\pi fc})^2}}=\frac{V_{collector}}{\sqrt{2}}$$
but when I simplify I get:
$$f=\frac{1}{2\pi C_3\sqrt{R_L^2-R_C^2-2R_CR_L}}$$


texts:
In Below graph

Why Vertical line are so unequal distributed.
In you see in the graph d1 and d2 both are 10 Mhz. But their vertical line area is different why?
In X axis it takes 170Mhz (30Mhz to 200Mhz,200Mhz-30Mhz=170Mhz) to Cover the Half of graph , but in other it cover 800Mhz ( 200Mhz to 1000Mhz, 1000Mhz-200Mhz=800Mhz). How?


texts:
I have created Gerber files for one of my application circuit. While giving it for development, manufacturer is asking for thickness in microns.

My question is why thickness is given expressed in microns, not in mils/mm?

And what is start and finish copper thickness in PCB layout.

Thanks.


texts: How can I convert the current from a fan to the microphone headset input on an iphone?

texts: I am working on creating an anemometer (or wind meter) for the iPhone.  I am a programmer and know exactly how I could do this on the software side of things, but I am a complete noob when it comes to electronics.  I have seen many other posts about putting voltage or an audio line to the microphone, but I'm trying to convert the current generated by a small spinning fan into a microphone input that I can measure on the iPhone.  How can I make sure that the volts generated by the fan will appropriately scale to the input of the iPhone microphone?


texts:
I'm currently designing a device, which consists of a STM32 microcontroller with USB 2.0 support, USB 2.0 hub and few dimmable leds.

STM is connected to the hub, along with few other devices. Hub is then connected to a smartphone via a USB-C connector.
The device has two modes of operation:

When connected to external power source it has to operate as upstream facing device (UFP, USB hub is connected to smartphone), and power SOURCE.
When external power is disconnected, it should switch to power SINK, while maintaining it's data role (UFP, all devices still connected to hub should be visible to smartphone).
The device has a microcontroller, which can send power role swap to the smartphone.

I'm not sure if I'm understanding the standard correctly, but:
STUSB1600A is only a controller, without Fast Role Swap
while TPS65987D I think is an overkill for the task (or maybe I'm wrong?)
Could You please advise some sensible solution?


texts:
I have an ISR putting in bytes from the UART on an AVR XMEGA into a circular buffer. Every byte received, also increments RX_COUNT. I copy the circular buffer into a local buffer if it is at least two bytes for a potential "#A" command.

The protocol I am using is #A, #B, #C, etc. The problem is I am searching for the sync char, '#' and they seeing what the next byte is, and checking if it is a valid command. The issue is, sometimes if I send a string like aaaaaaa#A it doesn't execute the command. I'm simulating garbage data to see if it will ever sync to the byte. How can I make sure that I will eventually sync to the start of the message?

Periodically, I have from my main function, check how much data is available in the circular buffer. If there is at least 2 bytes available, I copy the circular buffer into a local buffer:

USART_RXBufferData_Available() returns true or false is there is any data in the circular buffer.

Another question is, do I even have to copy the circular buffer into a local buffer? What is generally the best practice to decode a serial packet similar to this?

    #define MIN_MSG_SIZE 2 // Command is #A, #B, #C, etc...
    bool dataAvailable = false;

    ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
    {

        // Copy Circular buffer into local buffer

        if (USART_RXBufferData_Available(&UARTCom1))
        {
            if (UARTCom1.buffer.RX_Count >= MIN_MSG_SIZE)
            {
                for (int i = 0; i < MIN_MSG_SIZE; i++)
                {
                    localBuff[i] = USART_RXBuffer_GetByte(&UARTCom1);

                    UARTCom1.buffer.RX_Count--; // decrement RX count
                }

                dataAvailable = true;
            }
        }

        else

        {

              dataAvailable = false;

        }
   }

if ((dataAvailable) && localBuff[0] == '#') // Check if there is a new Message AND Check Sync Byte
{
        uint8_t data = localBuff[1];
        PORTR_DIR = 0b00000011;

        char led0Msg[] = "Turning ON LED0\r\n";
        char led1Msg[] = "Turning ON LED1\r\n";
        char ledoffMsg[] = "Turning OFF LEDS\r\n";

        switch (data)
        {
            case 'A':
            UART->transmit(led0Msg, strlen(led0Msg));
            PORTR_OUT = ~(PIN0_bm); // Turn on LED0
            break;

            case 'B':
            UART->transmit(led1Msg, strlen(led1Msg));
            PORTR_OUT = ~(PIN1_bm); // Turn on LED1
            break;

            default:
            UART->transmit(ledoffMsg, strlen(ledoffMsg));
            PORTR_OUT = (PIN1_bm | PIN0_bm); // Turn off BOTH LEDS

        }

        memset(localBuff, 0, sizeof(localBuff)); // Clear the buffer
        return true;

    }


texts: Wireless Sensor Nodes for Arduino-based system?

texts:
I'm new to electrical engineering, but have a software development background so I apologize if I'm missing something obvious. I want to tinker with sensors that interface with an Arduino, however, the use cases that I have in mind would require the sensors to be able to interface wirelessly with the Arduino. In my research so far, I've found that it seems common to use a sensor that is hard-wired to an Arduino, with the Arduino being wireless itself, so, you would need one Arduino for each wireless node. This wouldn't be practical for me in terms of cost.

I'm wondering if there are practical sensor nodes that have wireless capability, as I don't want a 1:1 sensor node to CPU ratio, rather, I'd like to have basic sensor input wirelessly to a single, centralized Arduino, which I would then connect to a full-fledged web server. Any info on this is much appreciated.


texts: Using a decade counter to send 10 different signals across one wire

texts:
I need to create a digital controller for a underwater ROV I am making for my Vocational class I take. I have created a prototype of what I want, but I'm kind of unsure of its effectiveness. It sends 10 signals over a single wire from the transmitter to the receiver. Ideally, I want to make this capable of being wireless, but unfortunately, neither wifi nor 2.4 frequencies work, and I dont have any money to put into a nice 750Mhz one. So, I created it in a way that, should I find or make one, it can easily be adapted.

I created a device that sends 10 signals using 3904 transistors at the outputs of a 4017 decade counter, then I provided a clock signal from a 555 IC, tieing together the transistors' outputs into one line. On the other side, the receiver, I used the 4017 decade counter, set at the same clock signal as the transmitter, to decode it by having the one line from the transmitter connect to the collector of ten 3904s. Then, the decade counter to have each output connected to the base of the 3904 on the receiver. It then outputs this signal through the receiving 3904's emitter. I am working with limited supplies. Some things I need to know are:

How fast can I set my clock frequency without having problems?
Can anyone see why something like this might have problems?
Has anyone ever tried this before? And did they have problems?

Also, if anyone has a 750Mhz circuit diagram laying around, can you pass it on?

Thanks in advance,

Tim


texts:
I'm new to audio and I want to ensure if it's proper circuit for integrate MAX9860 codec and EMG-610P microphone?

EMG-610P details:
https://www.monacor.com/media/FLE/EMG610P.pdf

MAX9860:
https://datasheets.maximintegrated.com/en/ds/MAX9860.pdf

Thanks for any answer.


texts: Does the capacitance values matter in a full wave voltage doubler?

texts:
I've simulated the following schematic on Cadence, and another less professional simulator called 'everycircuit'.

I initially had a C1 = C2 = 10uF which simulated correctly on both simulators. Then I realized that I did not have the correct voltage rating 10uF in my kit, but did have 470pF rated for 500V.

So I go into Cadence to test out the 470pF value, and it did not like that at all. Gave me a much lower voltage than what was expected. Everycircuit didn't seem to care at all, gave me the correct output.

I've since purchased some 10uF capacitors, but they are HUGE and would cause problems fitting them in between the rest of the components. I've already soldered the 470pF ones onto the PCB and am wondering if it will be necessary to spend the time desoldering the tiny pFs.

Does the capacitance values matter? Is Cadence just being finicky again?


texts: Part identification - SMD transistor or MOSFET

texts: I’m trying to identify the following small... probably MOSFET? The ‘X73A’ marking doesn’t help me find anything. It’s in a controller recharging circuit and gates on a signal from the controller, I believe by allowing power to flow when a controller is present and not fully charged.


texts: How to design a latch from a truth table

texts:
I am trying to design a latch using a truth table. The inputs to the latch are En and In. I think the circuit implementing the truth table should not change output when En is low, and output In when En is high. This is the truth table:

En | In | Prev | Out
0  | X  |   0  |  0
0  | X  |   1  |  1
1  | 0  |   X  |  0
1  | 1  |   X  |  1

It results in the following circuit:

simulate this circuit – Schematic created using CircuitLab

I haven't seen this while looking around at latch schematics. Am I missing some concept here? Is this an incorrect latch?


texts: How is 555 astable timing affected by a resistor on Vcc

texts:
I am trying to build a circuit that will plug in to a cell phone and let me read the value of a thermistor by generating a tone to the microphone, where the frequency is a function of the thermistor's resistance.  I have a prototype in TINA, but my timings are being affected by the resistor on the microphone / power line.

I'm using a TLC551 because it tolerates lower voltages than the 555, but the timings should not be affected by this substitution.

The transient analysis shows that I've got a frequency here of less than 1000hz.  For the values I have right now (Ra=5k, Rb=10.27k, C=47nf) I would normally have a frequency of 1200Hz.  Even if I try adding the cellphone resistance to Ra (Ra=7.2K, Rb=10.27k, C=47nf) I should still be getting 1100hz.  If I try remove the resistor in the cellphone section of the schematic, the timings match predicted 555 timings.

So, my conclusion is that putting a resistor in front of the Vcc input to the TLC551 is decreasing frequency.  The problem is that I can't figure out how to work that drop into the timing calculations.  To be able to read the thermistor, I have to be able to work backwards from frequency to deduce Rb.  Does anyone have any thoughts on this?


texts: How to slow down an 12V electromotor/fan

texts:
I just bought a cheapo fan like this on Ebay, and it's intended to be used in a costume for Halloween:

http://www.ebay.com/itm/Computer-VGA-Video-Card-Heatsink-Cooler-Cooling-Transparent-Fan-40mm-12V-2pin-x-/181701435335?hash=item2a4e3fdfc7:g:mqQAAOSwPYZU-H39

1) It's 12V, which is fine, but I'd like it to go slower. Is this possible, or is it simply a matter of on/off?

2) If the answer above is yes, would a slower fan draw less power from the batteries?


texts: LM339 Lipo Battery Voltage Tester Circuit - How does it work?

texts:
After reviewing the eevblog video on OpAmps and various other videos on the LM339, as well as copying a circuit which works, I am still genuinely confused on the math / logic behind this, which makes it hard to move on to more complicated and customized circuits.

To the best of my understanding, a circuit like this comparing voltages from two sets of voltage dividers should result the same even if the input voltage changes, because the difference between the two remains the same.

Here is the circuit in question:

simulate this circuit – Schematic created using CircuitLab

Note: This circuit was copied from this instructables article
I actually changed some of the resistor values in real life just to see if it would change the voltage range in which the LEDs would light up, and it did.

Since the V1 voltage source, which in practice is a Lipo battery, can be anywhere from 3.2v - 4.2v, I tested it in the CircuitLab simulator. According to the simulator, there should be voltage on all LEDs all the time, which makes sense to me since VCC is changing for both sets of voltage dividers, so the difference should remain the same, thus LEDs will either be on all the time, or all off when the voltage is too low.

In real life (and in the article) however, it doesn't work that way! The LEDs ACTUALLY light up at different voltage levels depending on what voltage is input at V1!

How is this possible?

Ideally, I would like to be able to do the math myself to figure out what resistors I need for what desired outcomes.

Thank you for any input!


texts: Relay component to schematic, are these the same?

texts:
I'm new to PCB designing and schematics and have chosen this component from the eagle library as it said G5l and showed a similar component to the one i have, but the terminals donit appear to look in the right orientation as seen below, however i did my best to connect them.

So is this a correct representation of my component?
and if yes is it correctly connected?


texts: Remote indicator light for alarm panel when armed

texts: I have an security alarm panel that I would like to have an indicator light turn on when the system is armed. From what I can see there are no remote contacts or anything to do this from the alarm panel, so here is my idea. I would like to power a relay from the led that shows the system is armed. Is there a low power ssr that I could hook up to the led solder points or an easy circuit with a transistor that would accomplish this. Or am off my rocker. Any ideas appreciated.


texts:
I'm currently working on a project where a sliding metal box is mounted on a metal pole. The box moves up and down. At the top of the metal box is a small processing unit that needs to know the distance between it's position and the ground. I'm currently investigating placing an IR or ultrasonic distance sensor and simply measuring the distance to the ground that way.

Since i'm just a software guy that has never learned electronics properly, I was wondering if there is some alternative way to measure the distance to the ground, maybe making use of the conductivity between the sliding box and the pole. Is it possible to use some kind of cheap device mounted at the bottom of the pole and the appropriate sensor on the box for this purpose? Or should I just stick with the IR or ultrasound?

Some more info:

I can't run a wire between the 2 devices to make a closed circuit. Or make any drastic changes to the pole (no magnetic or optical encoders).
The device on the bottom and the appropriate sensor should be about 20 dollars (or less)
I need to measure distances ranging from 10cm to 2m with a resolution of about 0.5cm


texts: How is the current through resistor same as collector current in this circuit?

texts:
My textbook says that the current through resistor will be same as the collector current when the diode shown matches with the base-emitter diode internal to the transistor. Could somebody kindly explain how is this possible.

So far I have :
$$I_R = \dfrac{V_{cc}-V_{be}}{R}$$

I'm struggling a bit in calculating how this current splits into diode and the base of the transistor. Any help is appreciated. Thanks!


texts:
I have the following circuit:

I have two questions:

Is it possible to implement this circuit with non-matched MOSFET transistors?
How can I calculate the resistance to connect both in I_in and I_out?

Thanks


texts: Mobile power bank to power electronic system

texts:
I am working on a project where I am trying to use a mobile battery power bank as a supply to my system. The battery power bank can provide 5 V @ 2.4 A. The output of this power bank goes into 2.1 mm DC Jack installed on my platform. At the input of my platform, I have a boost converter to transform 5 V (from battery power bank) to 6 V which is used by other circuits in my system.

I see that the input 5 V gets discharged in a periodic manner approximately with 2 s period which causes the output of my boost converter to also vary periodically and reset the other circuits. I have verified that this behaviour occurs even when the boost converter is not loaded and not connected to any other circuits.

However, everything works correctly if I supply my system with a bench top power supply instead of a power bank.

So coming to question, do you guys know what might be really happening here with power bank supply?


texts:
I am trying to set up the chip so it will detect a rising edge on a pin then start outputting a square wave on the next pin over after that.

I have the interrupt turned on but I don't know how to say "if interrupt is triggered, run the wave generator". I've scoured the data sheet but I can't seem to understand it.

; New asm data section
    AREA square_func, CODE, READONLY
; Export back to C
    EXPORT square_wave
    ALIGN
square_wave
    LDR     R1,=0x2009c000      ; Pointer to base of port 0
    LDR     R2,=0x00000001      ; To control pin 0
    LDR     R3,=0x00000001      ; For XOR to invert pin 0
    STR     R2,[R1,#0x00]       ; Set pin 0 to output (base+0x00)
    STR     R2,[R1,#0x14]       ; Turn on pin 0
    LDR     R4,=749             ; Set up timer
    LDR     R6,=0x40028090      ; Interupt pointer for port 0
    LDR     R7,=0x00000002      ; For pin 1
    STR     R7,[R6]             ; Set pin 1 to rising edge interrupt
loop
    SUB     R4, 1               ; Decrement timer
    CMP     R4, 0               ; Compare to 0
    BNE     loop                ; If !0, keep looping
    LDR     R4,=749             ; Reset timer
    EOR     R2,R3               ; Invert bits
    STR     R2,[R1,#0x14]       ; Invert pin
    MUL     R3,R3,R3            ; To waste cycles, ignore (1*1=1)
    B       loop                ; Restart loop
    ALIGN


texts: Battery recharge protection for a dual-power ATtiny board

texts:
I have a small board with ATtiny85 and it has a button cell battery socket on it. The battery that I'm using is CR2032 rated 3V. At the same time, while programming it there will be second power source from the USB programmer - that is usually 5V or 3.3V depending on the programmer.

In all cases the buttons cell battery will be connected in parallel with another power source of a higher voltage and that could cause problems.

I'm trying to avoid putting additional switch/jumper to have battery on/off while programming the micro-controller.

Q1: Is the assumption, especially in that particular case, that connecting battery and higher voltage in parallel could case problems correct?

One way to solve that issues is probably to put a diode in series to the battery - schottky will be better, but still there will be some drop on the diode and that could be critical for the ATtiny.

Q2: Are there any, other than using schottky diode, solutions for that issues that do not require too many additional components?

The power consumption of the board is about 15-20 mA.

Please note that the board is very inexpensive and the additional protection circuit that I'm looking for should be with inexpensive components as well.

Thanks in advance.


texts:
I'm trying to buy connectors for WS2812b LED strips. I have already found the item on eBay, but cannot find it on Digikey as Digikey has a gazillion of connectors.
The connector I am looking for looks like this, with three pins. Does anyone know what these connectors are called?


texts: Is my redundancy identification and K-Map grouping correct?

texts:
(Problem 7). Am I correct in saying that (m2, m6) the one circled in purple on the k-map is redundant? Also, if that is the case, how do I remove it from the boolean expression? I mean I turned that subcube into it's boolean expression form and got m2 = X'YZ', m6 = XYZ'.

(Problem 8). Did I do my subcubes wrong cause from the looks of it (4,5,12,13) would be considered unessential, but when I list them out: I don't cover all of the min-terms if I leave it out?


texts:
I want to know how can I heat a plate at 2KW using an electrical circuit. I need this circuit for a research project. I have to heat a large area so I am hoping that I could use something like a wire mesh to heat the plate.

I was looking to directly supply 220V AC to a resistive wire, but my advisor says it might be dangerous to do so.

I would be grateful if you could help me out with the circuit.

Plate Dimensions: 400mm x 64mm base area.


texts:
I have recently got Multisim 13.0 and I see some changes on it. It doesn't have the traditional footprints for AND, OR, NAND, NOR, XOR etc. Why?
When I add 7400N on the design, it has this icon:

I should get this instead:

simulate this circuit – Schematic created using CircuitLab
I am a beginner, and obviously a student, so I might have taken things wrong! Please explain me what is happening and how can I restore the standard footprints?


texts: Which of the impedance values below represent an pasive dipole that absorbs both active power P and reactive power Q, and why?

texts:
I stumbled upon this exercise and I can't find anything in my notes regarding to this notion where it absorbs both kind of powers. You guys might have any ideas?

These are the impedance values:

Z1 = 2-3j [Ohm]

Z2 = 3 [Ohm]

Z3 = 2+3j [Ohm]

Z4 = +2j [Ohm].

I also need to justify theoretically. Looking forward to hearing your knowledge


texts:
yesterday when i ask about driving circuit, someone told me that it is a little use in optocoupler when i use the same ground everywhere. because so far (iam a green hand in electronic) i just connect the ground to the netral phase, i don't know how to create or connect the ground properly, so how to create a grounding, or how to connect it wisely?
from this picture also it has some grounding but not connected one another


texts: Inverting Op amp with 60 degree phase shift instead of 180

texts:
I designed this 741 inverting op amp with a gain of 50. After wiring and testing I obtained a gain of 130 and a phase of 60 degrees. I don't understand why the phase is not 180. Also I switched the 741 with a MCP642 and did not see a noticeable change.
Assistance would be appreciated. Thank you.
R1 = 6.8 k Ohm
R2 = 330 k Ohm


texts: avrdude problem with sck , how to recover locked avr with external clock fuse bit

texts:
I wrote this code:

#ifndef F_CPU
#define F_CPU 1105920UL
#endif

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

int main(void){
    DDRC=0b00100000;
    while(1){
        PORTC=0b00100000;
        _delay_ms(5000);
        PORTC=0b00000000;
        _delay_ms(1000);
    }
}

I programed it in atmega8:

sudo avrdude -c usbasp -p m8 -U flash:w:my.hex

micro programed ,OK, not problem:

i wanted use external crystal; then i connected crystal 11.0592 to pin 10 and 9, and rewrite fuse bit:

sudo avrdude -c usbasp -p m8 -U lfuse:w:0xE0:m

fuse bit rewrite and OK.not problem

now i realized this value 1105920UL is mistake, i edit code and change 1105920UL to 11059200UL ,

but when i programed micro, avrdude get me error:

$sudo avrdude  -c usbasp -p m8 -U flash:w:my.hex

avrdude: warning: cannot set sck period. please check for usbasp firmware update.
avrdude: error: program enable: target doesn't answer. 1
avrdude: initialization failed, rc=-1
         Double check connections and try again, or use -F to override
         this check.

avrdude done.  Thank you.

My micro is lock?
or i must rewire sck?
how to i resolve this problem?!?

Thank you


texts:
I am trying to recharge AA Battery (rechargeable, 1.2v, 1000mah) with DC Generator which outputs around 3v to 5v.

The input for DC Generator is from another 1.5v rechargeable battery with a step up voltage booster.

(Though I am not sure how much amps output i am getting from DC Generator,and I don't know how to calculate it.)

After some googling I come to know I need to use voltage regulator to give some constant voltage to battery for recharge from DC Generator.

How much voltage I need to give to battery for recharge and do I need to consider the amps?

Also is that possible to get load and recharge the same battery simultaneously?

I am just learning electronics myself. Some simple words to explain this without much formulas will help me to understand much quickly.

Thanks!


texts: Need help trying to design an H-Bridge to power electromagnet

texts:
I am trying to design an H-bridge inverter to supply maximum current to my coils. I need to supply as much current as possible so that I can make a electromagnet whose polarity constantly flips so that i can levitate a moving Halbach array over top of those coils.

I've tried a number of things to make my mosfets as efficient as possible but when I enter in my Rds values into PSIM the current drops to 4mA. I have a DC power supply capable of outputting 18V and 10A.

when I run the simulation I get that the current is through the coil is only 4mA which is nowhere near enough, I'm not sure if I am simulating something incorrectly or if thats correct based on the way the circuit is designed. Does anyone know how to maximize the current the coil? also even with the RC snubber circuit my MOSFETS are heating up alot! is there a better way to reduce that? My PWM frequency is at 120Hz from an arduino, and its a 40% duty cycle.

My coils have 220 turns and are 18 gauge wire, with a radius of 2cm and a length of 2.5cm, they are air coils I dont have any core.

My mosfets are
FQP27P06
FQP30N06L

Thanks in Advance

EDIT
After fixing the orientation of the PMOS my output looks good.

However I'm finding that the magnetic field produced through these coils is not strong enough to levitate my pod. Is there something I can do to make this stronger?

EDIT2

simulate this circuit – Schematic created using CircuitLab


texts: 74HC4051 multiplexing and voltage divider

texts:
I need a voltage source for an Arduino analogue input. I'm making a capacitive sensor with an NPN BC548B transistor. In the emitter, I connect the GND, in the collector, I connect the analog port of the arduino, together with a 5v and a 10k resistor. So, when I'm not touching the transistor's base, there's no GND to interact with the voltage divider, and the arduino reads 1023. When I touch the transistor, GND is activated and current flows the collector producing a voltage across the 10K resistorand the arduino reads something much less than 1023, sometimes almost 0, like 12 or 50.

Since I want to read multiple capacitive sensors, I bougth a 74HC4051 chip to multiplex all the sensors. My idea was to include the voltage divider after the demultiplexing, so I would use only one transistor and one resistor at the port 0 of the arduino, and I'd only switch between the sensors using the multiplexing. The problem is that when I tried to do that, it didn't work, I got lots of random values in the reading. Also, in this scheme:

he uses the voltage divider for each LDR before the demultiplexing, not after. Is there a reason behind it? I believe that the 74HC4051 chip has some internal resistance, but I thought it'd work even with this tiny resistance. Is there something I'm making wrong?

Here's what I am doing:
In this scheme, I can read exactly as I intended to do, but when I try to switch the transistor base with the multiplexer, it will present strange results. Also, I couldn't just wire each 'analog 0' of the scheme to a different port of the multiplexer, it'd use too many transistors and resistores.


texts: Please help me understand the following light-controlled relay circuit

texts:
I used the following circuit to control the outdoor light, and it works as I wanted.

I am trying to understand the circuit and it looks like a comparator circuit,
but I don't understand the use of 100 kOhm feedback resistor.
Also how to choose the resistor values 100 kOhm, 15 kOhm and 100 kOhm pot?


texts: How do I measure the voltage coming out of a USB port?

texts: If I attach a USB cable to a USB port, and then strip the wire at the end, then how do I connect a multimeter to it to measure the voltage?


texts: Rebuilding Makita NiMH Battery with Cells of Bigger Capacity. Will it Charge Properly on the Old Charger?

texts:
This is for a Makita 6932FD impact driver. It runs off a 14.4V NiMH battery of 2.6Ah. I ordered sub-C cells (with solder tabs, don't worry :P) that are 4.2Ah.

I was reading about DIY NiMH chargers just out of curiosity. The author used a PIC to monitor charge termination based on 3 conditions:

dV/dt
Temperature
Time

So that got me thinking, I believe the highest capacity of OEM battery was ~3Ah. So will the charger be able to fully charge it? Or will it take too long, and get cut off? In which case, I'd have to

Use it as is
Unplug then plug in the charger again to "reset" the count
Get a different charger, probably one for RC batteries as this is the target audience of the cells I bought


texts: CPLD is (sometimes) not incrementing counter

texts:
I have this simple program running on the Altera EPM240 that’s sometimes not doing the counter increment.

reg trigger_state;
reg [7:0] trigger_count;

always @ (posedge clk)
begin
    if (trigger != trigger_state) begin
      trigger_state <= !trigger_state;
      trigger_count <= trigger_count + 1;
    end
end

clk is running at 50 MHz, and the trigger signal in the picture at 1-2 kHz.

In the picture (trigger=6, trigger_state=4, trigger_count[1]=1, trigger_count[0]=2)

As you can see, trigger_state always follows the input signal (trigger), but the counter (2) is sometimes not incremented.

What could explain such a behavior?


texts: What is my microcontroller power duty cycle?

texts:
Say I have a uC active for 1s every 100s, sleep otherwise. This will lead to 1% duty cycle.

But what if it is active ones every ten seconds, and once every 100 seconds, and then once every week? Over what period of time do I calculate the duty cycle?


texts:
I was just wondering how the microchips are actually designed. I was watching the Apple presentation on the A7 chip and they were saying there is over a billion transistors on the chip. To my mind, it would take a team of thousands to design that, and yet there seems to be a newer, faster, bigger chip every year.

Are computer programs or people designing the chips?


texts: High-Side output of IR21094 Gate Driver does not switch

texts:
I am trying to simulate an IR21094 based half-bridge inverter on LTSpice. The design follows the recommended design on the datasheet by the manufacturer (https://www.infineon.com/dgdl/Infineon-ir2109-DS-v01_00-EN.pdf?fileId=5546d462533600a4015355c7e85b1679).
The issue? The low side NMOS switches on and conducts. Also, the LO signal can be seen as switching. However, the high side NMOS does not appear to be turning on. This can also be seen from the HO waveform. Basically, my output inverted waveform does not reach the supplied bus voltage (as in I would like it to reach 50 V, but it only reaches the Vcc).
I have placed screencaps of the HO and LO outputs.
Here is a screencap of my schematic:

And lastly, here is a screencap of the voltage across my resistor.
Any and all help with fixing this would be greatly appreciated!


texts: PIC ISR - check every interrupt source or just one?

texts:
I'm curious if there are any particular wins for using a call instead of a goto when checking each interrupt source in an ISR. My current code would do something like this:

.intr   CODE        4

    pagesel     $

    btfsc       INTCON, TMR0IF          ; Timer0
      goto      Timer0_Entry

    banksel     PIR1                    ; Bank #0
    btfsc       PIR1, SSP1IF
      goto      I2C_Entry               ; I2C Peripheral
...

but that is on a enhanced midrange pic16 where the context save is done for you. If I was on a PIC16F88 say, there would be a (minor) win for avoiding the whole tedious context save in a situation where two simulataneous interrupt sources were pending.

Doing it with gotos implicitly creates a priority list which can stall other sources - if I had multiple interrupts from one source, that source would stall the other irq sources until it stopped. I hit that once by forgetting that the serial port irq flag is asserted by default.

But other than that, is it just a question of taste? The hit you take (in a multiple irq situation) by doing a retfie and then heading back into the ISR immediately doesn't particularly severe.


texts: Level shifting: from 0-3.5V range to -2/1.5 range

texts:
I have a signal (digital) which has output levels of 0V (logic 0) and 3.5V (logic 1).

I would like to know if it is possible to shift it between -2V (logic 0) and 1.5V (logic 1).

I found here on stackexchange and on google various example, but they all assume positive levels (0-5 or 0-3.3) and I don't really understand how to make them work in my case.

Thanks for all the help

EDIT after a couple of questions:

I have available easily on board: -2V, 0V, 1.5V, 5V
I am sending the signal to a CMOS logic gate

EDIT 2:
Just to add a bit more to my question:

if you look at this thread
Level shifting a +/- 2.5V signal to 0 - 5V

the first answer provides a very nice circuit to do level shifting.

My problem is that I do not understand how to modify the circuit to fit my needs (see above).

In particular, I am quite puzzled by the supply value of the OpAmp. It looks to me I should use +1.5 and -2, but then I get lost in understanding what is going on.


texts: Any thing better to start learning with other than an arduino?

texts:
I've been wanting to get into electronics for a while, I've seen loads of people say that arduino is the best way to go for starting out in electronics. After saving some money I bought a knock-off arduino board with an LCD and started programming. I found it horribly boring. It was just too easy in my opinion, I was hoping to move bits around and interact with hardware, but all I did was call a function to print to a line of text to the LCD.

I'm hoping for something a little harder, Ive got 2-3 years of C/C++ experience and was wondering if there is any 'true' electronics I could get my hands dirty with. As in actually interacting at a low level instead of using a function call.


texts: How does Near Field Communication protect from unwanted long-distance communication?

texts:
According to Wikipedia Near Field Communication is intended for short-distance communication - something like less than a meter. I wonder how could this limitation be enforced?

Usually there're these factors that limit radio communication range:

radio waves being absorbed and/or diffused by obstacles
other radiation being present
initial signal strength
receiver sensitivity

At short distances the latter two factors are the key. Usually specifications will regulate the maximum transmitter power and expected receiver sensitivity and this effectively sets up the communication range.

Now suppose I want to create some fraudulent device that would communicate with devices without owners' consent. The specification will say the transmitter must have no more than some power, but I could easily make it times more powerful. The specification will say some level of sensitivity is required, but I could make a more sensitive receiver. I suppose with such adjustments I could make a device that would communicate with ordinary devices over several meters distance and no layman would notice that.

How does NFC protect from such abuse leading to unwanted communication over distance longer than expected? How could maximum communication distance of less than a meter be enforced?


texts: Electrical Connectors - To Split Pin or Not To Split Pin, That is The Question

texts:
I'm working on repairing a swimming pool hot tub heater.  Feed is 240v 1Ph A/C power and it uses 18 gauge wire throughout.  Apparently something got wet and I can see signs of a thermal event within the an electrical connector joint.  I'm replacing the connector and the terminals with all new ones. (And yes, I will check for other potential shorts before I power this puppy up.  My initial guess is it was powered up during a rainstorm, and the water caused the fault. )

The terminal system is the "Universal Mate-n-Lok" AMP from TE Connectivity.  Male/female hardshell connectors, and their corresponding terminal pins/sockets are readily available from electronics supply warehouse stores.

I see they offer "split-pin" and non-split pin designs.  The "split-pin" design is clearly designed for an bit 'more' of interference fit... its "in phase O.D." = 2.21 to 2.08mm   The non-split pin design has an O.D. of 2.13 to 2.07mm.  (Female terminal I.D. is 2.06 to 1.98mm)  I can't find anything from the manufacturer on usage recommendations on the two different designs.  Reference, MFGR PN: 350218-1 and 350687-1

So here are my dumb questions.  Split pin or non split pin?  The prices are exactly the same.  Why that choice?  And if it doesn't make any difference, and they both perform the same, then why did the manufacturer tool them up that way in the first place?


texts:
I have an FPGA design that works ok in the lab, but timing analysis warns of some serious negative setup slack at worst case temperature and voltage.

I'm curious, what might the derating be? It's not in the datasheet. I found some tables online that suggest up to 40% at worst case temp/voltage, but for an unlisted process. The device we have targeted is on the 28nm process.

Does anyone have any experience or know how sensitive the timing is to voltage/temperature? particularly for 28nm?


texts:
I have been studying the effects of using capacitors in different locations and one I have come across is split caps across a signal output. I've re-created the design in LTSPICE and screen-cap'd it:

Let's assume for the sake of argument that the Signal In and Signal Out are already balanced to be half of Vcc, (24V_Ref in the screencap). Is there anything gained by using the above capacitor layout compared to the following simple RC filter? My gut tells me that if the signal is already balanced to half Vcc, then it IS useful, but playing with it in LTSPICE doesn't show any difference between these two layouts.


texts: How to make a RF additive mixer for two inputs in same frequency band?

texts:
One of the most common designs for a SSB modulator (phase shift method) involves an additive mixer as the very last stage.  Here is a block diagram for reference:

This additive mixer must provide isolation between the two inputs.  I am only aware of one method for doing this, which is to "couple" the signals onto each other using well-chosen filters.  Here is an example in the case of a multiplicative mixer:

However, this method only works when the two input signals are vastly different in frequency.  How would I isolate two input signals when they occupy the same frequency band?

Given that I am dealing with RF frequencies, op-amp mixers are out of the question.  Surely there is an active circuit design which provides sufficient isolation, with low distortion and able to run on a single ended supply.


texts: How to decide the Temperature range of an IC?

texts:
I am using a MAX3241E ic in a device that has to run 24x7 out in the open. I am facing a problem deciding the temperature range of the the IC. Since it is out in the open, the ic has to withstand the heat from the sun plus the heating effect due to losses and resistances, etc. I am living in Delhi, India and here the temperature easily reaches 45 degrees. This ic that I have choosen can bear a max temp of 70 degrees. Should I use this ic or should I go for a higher temperature one? Also please tell how should one decide the max temperature of any ic?

Datasheet of the IC: - http://www.mouser.com/ds/2/256/MAX3222E-MAX3246E-99333.pdf


texts: Unpolarized Capacitors in place of Polarized ones

texts:
I have found some projects of interest, and on them there are generally a polarized capacitor in the range of 10 multiple (0.1uf, 1f, 10uf, 100uf, etc), and I do not know why I ordered a lot of polarized capacitors in the 47 range (0.47uf, 4.7uf, 47uf, 470uf and 4700uf), but unpolarized ones of the 10 multiples range.

If I place a unpolarized capacitor in place of a polarized one, can it discharge the wrong way, and burn my circuit?


texts:
why is there 0.7V instead of 1.2V on the common emitter?

if you go through Q1 mesh : Ve = 0.5+Vbe = 1.2 instead of Ve = 0+Vbe = 0.7 from Q2.


texts:
I have a 3 phase motor and 3 phase power supply (400V, 50Hz)

Currently this motor produces 1.5hp in torque and ~1750rpm. I need it to produce less.

My question is:

Is the best way to go about this, a rheostat or a VFD? The cheaper the better.


texts: Pipelined vs Low Latency implementation of cube of a number in Verilog

texts:
I was studying about FPGA design and then came across this terms Throughput and Latency. So the author provided an example of a highly pipelined implementation of finding the cube root of a number:

which apparently has the following logic diagram:

.Then the author has tried to reduce 'Latency' by writing the code like this:

which unrolls like this:

My question is to me both the implementations appear almost identical, so how are they different? I understand blocking and non-blocking assignment, but how are they causing a different logic diagram in this case? How is it decreasing the latency of the circuit in the second case?


texts:
I encountered device made by Texas Instruments with label USB2ANY HPA665. It has LED, mini USB and FloppyDiskDrive-like ports.

I can't find any data-sheet, manual or resources what for and how to use this device. Looks like some kind of programmer/debugger? Can anyone help?

It has MSP430 microcontroller.

More pictures here.


texts: Is it possible to reduce range of an RF receiver or transmitter for LED Strip lights?

texts:
Background:
I recently purchased a couple of strip led lights with remote. These were installed in different rooms.
Problem:
The remote seems to be RF and not IR, thus all the lights in various rooms turn on/off together. This is pretty annoying at the least.
Learned from this thread that reducing transmitter range may not be possible.  <==This is what finally worked, hence edited the title!!
I wonder if there is any possibility to reduce the range of receiver (picture attached.)
FYI, the receiver is also the power supply.
I cut off the green circled coil and still this light works from the remote in other room.
What is the plate in the red circle?
Edit 1:

I tried wrapping the receiver/power supply in aluminum  foil (Like all around except the leaving space for prongs.) It surprisingly had no impact. This still puzzles me.
I have 3 remotes and 3 of these lights. One remote can control all.

Edit 2:

Adding two other pics of that RED thingy
Name on the Power supply is CNSUNWAY Lighting

Edit 3:
Found something that worked for me. Will post the answer below.


texts: Why does my crystal oscillator spike so much?

texts:
I just got a new oscilloscope (Rigol DS1102E) and I'm new to EE in general.

One of the first things I put on the scope was my 3.579Mhz "TKD" crystal oscillator.

What I didn't expect was the spike on each rising and falling edge (hope I said that correctly).

If you look at the attached picture, you will see what I mean.

So, what is that all about?  I'm building an audio circuit that uses the NTSC frequency to drive an SN76489.  The IC uses the frequency to generate square waves for audio so while my circuit sounds "good enough", seems like spikes like that would cause issues later on?

I don't have any resistors or capacitors on my circuit.  Just the OSC out to the CLK pin of the IC.

Also, what's the deal with the scope reporting ~3.597Mhz?  It seems to fluctuate in the 3.56 - 3.59 range.  However, when I put a 1Mhz crystal on the scope, it shows a nice 1.000Mhz frequency.


texts: lug identification on Carling rocker switch

texts:
I have a carling rocker switch (LTILA50-6S-BL-RC-NBL) 125V with red Neon light. The switch was turning the amp on and off okay, but no light.  I switched the power and accessory wires. Now switch turns on Amp but light is illuminated on off position.  Only markings are A by one corner lug, Center lug has a green pin stamped D, the last lug (opposite A Lug has no markings.  I have search the net for hours trying to verify which pins are power, Acc, and  ground.

Pics - Light on and amp off,

Amp on and Light off,

and Lugs.

Any help is greatly appreciated.

Steve


texts:
Nearly all of the railgun designs I've seen have arranged the capacitors in parallel. Why is this? If one arranged the capacitors in series, couldn't they achieve a higher voltage (and thus more current and a larger force on the projectile) while still maintaining the same capacity for energy in the capacitors? What advantage does adding capacitance provide for the railgun?

Wikipedia - Railgun


texts: Converting 5V to 3.3V with 100mV ripple max, preferably without board

texts:
I am working on a project in which there is an existing enclosure, an existing power supply board and a bought board that I need to interface with.

The board I need to interface with needs to receive a supply voltage with the following demand:

  +3.3 VDC ±5% with less than 100mV ripple

I don't that much experience in board design, so what I need to know is how to supply that 3.3V with the "less than 100mV ripple". I have 5V and 10V from that power supply board that I have.

The power supply board that I have uses the NCS6S1205C for 5V and NCS6S1212C.

Which components do I need? an LDO? a DC-DC converter? I suppose I also need components like inductors and capacitors to meet the <100mV ripple?
Can I do this somehow without a board? maybe put the voltage converter on the enclosure itself?
If I do need a board, I would love if someone can provide a reference schematic I can use, or provide me with a good component that has such a reference schematic in it's datasheet.

I did search and find some stuff like:

http://www.ti.com/product/TPS60201

http://www.ti.com/product/TPS60205

https://www.rohm.com/documents/11486/47257/BD99010_BD99011_Datasheet_Rev+003_EN.PDF

But I really prefer to ask here, since I need the simplest design that will use the least components as possible.

Thank you!


texts: OP Amp non-inverter amplifier - Do I have to use power supply to amplify a signal?

texts:
Im new to OP-AMPs I simulate a circuit using one op amp just to amplify the signal to the double this is my diagram

But im not sure if the Vs+ and the Vs- is useful in this case? I put the Vs+ to 5v and Vs- to GND and also remove it and it gave me the same result, did it matter if its or not connected?


texts: Determining the voltage of 5 phase PMSM motor

texts:
As a part of the project, I have to design a 5-Phase PMSM motor, for which want to know the following:

How to determine the voltage ?
What should be the ideal voltage to use this motor in an electric car? Provided the car has 12 battery packs of 12 volts ( i.e 144 V supply from the battery?)

If, additionally could anyone  suggest me some literatue, it would be a great help.


texts: Which would better suited for a CNC drilling machine: gerber or gcode?

texts:
I am planning to develop a CNC drilling machine for a college project. The idea is to export the hole coordinates and drill size directly from a .brd file on Eagle, which will later be read by an MCU for processing. We're trying to define which format to use: gcode or gerber. Any suggestion for a third option will be gladly welcome.

Which one is easier to work with or is better documented?

Also bear in mind that we want other students to be able to do the exporting from Eagle without much effort.

Thanks for your help.


texts:
I'm trying to understand what is going on here - this is in a normal house linked to the grid (240 volts / 3 phase), nothing extra. On two sets of plugs (next to each other), I measure 36 volts between ground and neutral. I see 240V between ground and live (in my minimal knowledge, this seems correct?), and 240V between neutral and live (again, this seems correct?).

In the appliances plugged into these plugs (I've unplugged all of them and get the same readings) you can feel a tingle when touching the metal housing (which I assume is linked to ground). The appliances themselves work just fine.

In all the other plugs in the house, I read zero volts between ground and neutral - this leads me to thing that the plugs showing the voltage are wired incorrectly / differently to the rest of the house.

Can any shed some light on what could be going on here? Should I be calling in my electrician?


texts:
In a project with FPGA stereo vision I use two MT9V032 cameras. The cameras are connected as in the application example in the data sheet.

In stereo output mode the data length is 18bits long. There is one start bit and one stop bit. So there are 8 bits for each pixel of master and slave camera.

In Application Note XAPP1064 I read that maximum bitlength of 16bits is possible for Spartan 6 Deserialization. Is there a trick to support higher deserialization factors?

As I do not need the start and stop bit, is there a solution to deserialize only the bits between start and stop bit?


texts: Interfacing a melody generator IC that drives speaker directly to an amplifier

texts:
[EDIT]

I have figured out the solution before, but forgot to update here. Actually you can just connect the two polarity of the amplifier directly to the two speaker out wires, which leads to a completely normal and clear audio quality. But if doing so, the signal may be too high for the amp, connecting an resisitor divider can solve this. Or even better, like one of the answer suggested, use an isolation transformer after the divider, which will isolate the output of melody generator from the amplifier. And actually this is how the product "Car Audio High to Low Level Converter", that you use to interface car audio that only comes with amplified speaker output to another amplifier, works.

However I still don't understand why connecting only one PWM output, along with ground, will bring in the noise. My assumption is that the two PWM output each carry a part of the audio signal, and if you only take one half it won't sound right.

[Original Question]

I have a msuic chip and it has a PWM output that drives a speaker directly. Used logic analyzer to check the output frequency which is about 60kHz.
Now I need to connect it to an amplifier. I have tried RC filter but there was a strange noise.
I calculated and adjusted R and C value but this didn't help.
What should I do now?


texts: How to analyze analog output waveform in Modelsim

texts: I want to analyze an output sine signal from my VHDL code in Modelsim. I have created a project and simulated the code. However the outout in the "Wave" window is in binary form represented as a 32 bit output. I tried to change my signal as a Analog signal in wave properties but nothing really changed. I would like to se an analog output signal in decimal format which resemples a sine wave. How do I do this?


texts: how to map a pid controller to a process

texts:
How do you "map" the output of a PID controller to a process?

Say you have a resistor, a thermometer, and a PID controller. The thermometer provides feedback, and the PID controller can control the electric current of the resistor. You want the resistor to run at X degrees, so you use the PID to regulate the current going through the resistor.

Do you connect the PID such that the controller sets the current to a certain level, or do you connect the PID such that the controller adds/subtracts current to the instantaneous current to reach the desired level?

That is, does a PID's output directly control the process output or does the controller's output keep changing a processes output to reach a desired level?

EDIT: Whooo man, did I write this? I asked this question 2 years ago when I was first fiddling around with a PID. Now, I can barely understand what I was asking. At any rate, @spehro pefhany's answer provided what I think I was looking for back then: a comparison of position- vs velocity-based control.control.


texts: Step Up Converter (Boost) is Wasting too much Power

texts:
I'm using a boost converter to run a brushless fan (10V, 5Watt, 0.5 Amperes) from a power bank with a 5 Volt output. The converter's efficiency is rated at approximately 85% (from 5 to 10 V). Theoretically the input side of the converter should have a 1 Amp current absorbtion. Instead I'm measuring 2.7 Amps (the power bank can't substain this). In other words to feed a 5 W motor I'm giving 13.5 W.

Are there some reasons for this? Maybe the brushless motor requires some Capacitance?


texts: Simulating AC-Coupling capacitor used in PCIexpress

texts:
I am trying to simulate and understand the AC-Coupling capacitor effect on signals with DC bias.
I have a signal which has excursions between let's say 0.5V to 1.5V, So, it has 1V(0.5+1.5/2) DC bias. I thought 1V DC bias will be removed from the AC coupled signal and output(Signal after capacitor) will have excursions in between -0.5V to 0.5V.
I may be wrong.please correct if i am wrong.....

But simulation gives waveform having excursions between 0 to 1V. I don't know How to explain this theoritically.
I have used LTspiceIV from Linear technology and also Micro-Cap. Both given same result.


texts: agilent 34903 Actuator/Relay card not working in remote mode

texts:
I have a simple SPDT relay on the 34903A card, hooked into a 34972A DAQ Unit.

The COM is a 5V supply from an external source,and I have the NO pin hooked up to an input externally as well.

When testing this relay on the front, it works fine.

However, I am unable to actuate it remotely. I send the following cmd:

"ROUT:CLOS (@301)"

I dont get any errors back and I get a return message from the cmd. However, the relay doesnt actually switch.

If I use the same command on an unused channel(@302), it works even remotely.

What is going on here?


texts:
I installed 6 battery-powered 1Watt LEDS in my dad's home to help when he has power outages. They worked as intended for some time, but recently begun to fail in an odd way. They no longer turn on immediately, instead seem to slowly warm up. At their brightest they are still incredibly dim. One seems to flicker dimly, while another does not turn on at all. I've never seen LEDs fail in this way (if it even is the LEDs at all)
Here is the schematic:

If I remember correctly, the LEDs where 1W ±3V. Something like this: Datasheet
My dad says over time the lights began to act erratically. Eventually half the lights stopped working, then a few weeks later they all stopped working (which makes sense considering I've got two strings of three).
I suspect one dud LED failed leading to a cascade of the rest failing, or mice chewing the wires in the ceiling.
The battery is measuring 13.7V
One of the LEDs measured 2.36V. This was after it had eventually "warmed up" and was shining very dimly. It was not warm to the touch like they were when they shone at full brightness. (Didn't measure the rest because its high up in the ceiling. I'm assuming they're all reading ±2.36V)
R1 = 8ohm (To limit current to ±660 mA)
R2 is a few ohms. Shouldn't effect the circuit.
What do you think the issue is? Has anyone experienced LEDs slowly failing over time in this manner? Will it be worthwhile replacing the LEDs, or do you thing they will fail in time again?
Any insight would be much appreciated.


texts: Can I convert to less AC volts to get more amps?

texts: I was wondering if I have (for example) an input of 12V and 100A DC, instead of going to, let's say 120V and 10A AC, if it could be converted into 100V for more amps. (I already know about loss so let's just assume this is a magical lossless system.)


texts: How to design a 5-32 decoder using 4-16 decoder with enable?

texts:
I am finding it hard to find a detailed step by step process. Do I have to make a truth table?

Workings so far: I can guess that I would need 2 4-16 decoders, which share the 5 inputs of the required 5-32 decoder, and gives 32 outputs. But that leaves me with 1 extra input that I can't cater to, where is it going to come from?


texts: Transimpedance Topology - from block diagram to schematic

texts:
As I work through learning the four topologies of negative feedback, I can't seem to figure out the transimpedance amplifier.

As far as I understand it, I need to consider my input as a current source.  The signal input \$i_s\$ is reduced by the feedback network \$K\$ so that the current \$i_{in}\$ entering the internal amplifier is attenuated.  Then the internal amplifier \$A_o\$ produces an output voltage \$v_{out}=R_oi_{in}\$.  That output voltage is applied to the feedback network \$K\$, which itself produces the output current \$i_f\$ that attenuates the input because of KCL.  So far, so good, I think.
What's missing for me is being able to understand how the discrete components in the circuit at right would apply to the block diagram at left.  I was able to perform this type of analysis for the voltage amplifier (common-collector here) and transconductance amplifier (common emitter with degeneration here).
For this example, where would I begin if I wanted to derive the open-loop gain and closed-loop gain in terms of actual circuit values?  How does \$R_C\$ in the schematic relate to \$R_o\$ in the block diagram?  How does \$R_F\$ in the schematic relate to \$K\$ in the block diagram?


texts: understanding how to set values when using all 8 bits from one address plus the next 2 of the next address

texts:
I hope that I am phrasing this correctly but here goes. I have been building a service for MSRDS to run my prototype board. People have probably seen me ask questions about this before. I have been pretty successful with it and I have an interface that lets me write and read from it but I am not sure how to deal with addresses like 0x53-0x54 where they use all 8 bits from 53H and then 2 more from 0x54.

For example I can set the address 0x4D (which controls whether or not the digital ports are input or output) to 0x01 and then set 0x4E to 0x01 and the LED I have plugged into the bread board lights up - that's easy because in both cases I am only dealing with a single 8 bit address my problem arises when I am trying to set the voltage on analog output O0. I thought I could just send two commands, the first setting the address of 0x55 to 0xFF and then setting 0x56 to 0xC0. I have tried various combinations of this however can't ever get the voltage above about 1 volt and I think it is because I am not setting the values properly.

Hopefully I have made this clear enough that someone can enlighten me as to what needs to be done in order to better understand what I am doing.

This is the code that actually handles sending the message over USB serial link to the I2C device. It's sort of complex and not really clear because it is posting to a service (the brick service), I have spent hours with it but I suspect it won't tell anyone else much off the bat. It's from a modified version of the NXT source code included in MSRDS samples. That being said I can tell you that it works pretty well when I am dealing with just one 8 bit address. Also not - it's called ReadFromI2cAddressHandler because with the lego USB protocol you always get back a 16 bit padded response - in the case you want to just write some data you just ignore it because it's all zero's anyway. If you want to see more of the code it's on my github account.

 [ServiceHandler(ServiceHandlerBehavior.Exclusive)]
    public virtual IEnumerator<ITask> ReadFromI2cAddressHandler(ReadFromI2cAddress readRequest)
    {
        var write = new LegoLSWrite
        {
            Port = _state.SensorPort,
            TXData = readRequest.Body.TxData,
            ExpectedI2CResponseSize = readRequest.Body.ExpectedResponseSize
        };

        Activate(Arbiter.Choice(_legoBrickPort.SendNxtCommand(write),
                                EmptyHandler,
                                f => LogInfo(f.ToException().InnerException + " " + f.ToException().Message)));

        Activate(Arbiter.Receive(false, TimeoutPort(80), EmptyHandler));

        var read = new LegoLSRead(_state.SensorPort);
        Activate(Arbiter.Choice(_legoBrickPort.SendNxtCommand(read),
                                r => readRequest.ResponsePort.Post(new ReadResponse {Bytes = r.CommandData}),
                                f => readRequest.ResponsePort.Post(f)));
        yield break;
    }


texts:
Some tiny background:

The reflection coefficient, \$Γ\$ can be calculated according to this formula:

$$Γ=\frac{Z_L-Z_S}{Z_L+Z_S}$$

For a transmission line, \$Z_S\$ is the impedance of the transmission line and \$Z_L\$ is the input impedance seen from the transmission line.

If you are using a closed stub on the transmission line, then \$Z_L\$ is 0 which results in \$Γ\$ being -1. A total negative reflection occurs. If you are using an open stub then \$Γ\$ becomes 1. A total reflection occurs.

For a rope, \$Z_S\$ is the impedance of the rope the signal is entering and \$Z_L\$ is the impedance of the other thing connecting it. If you try to whip the rope when the other end of the rope is connected to something fixed, like a building, then the impedance of the wall is 0, \$Γ\$ becomes -1 and you get a total reflection. If you whip and there's nothing connecting the other end of the rope then you get a total reflection. Right, nothing weird.

So the same equations can be used for both waveform mediums.

Here's an image of a rope being whipped, at the point where the rope goes from thin to thick, the  \$Γ\$ is calculated which describes what should happen to the wave, how much that should be reflected back and how much that should go through.

As you can see with the red arrow, going from a thick medium to a thin medium increases the amplitude, and that's why a whip works, because you hold in the thick end and the whip gets smaller and smaller which makes the amplitude of the wave so much higher and higher, amplified several hundreds of times.

In a transmission line, the same thing happen as in the above image if you got two transmission lines facing each other with different impedances.

Now, here's waldo, if I want to make a physical whip with a rope then I make sure to make the \$Z_S\$ to decrease from my handle to the other end of the rope, or I make \$Z_L\$ larger. Because then the red arrow effect in the image above appears. If I want the same thing to happen with my voltage in a conductor, I should do the same thing. How would that electrical whip look like?

I'm imagining that it would look like some kind of triangle /\ and at the bottom of the /\ triangle you apply some small voltage and at the top you get a massive voltage and possibly some corona appears if I would pulse a 9V battery to it. It would be wound in aluminum foil which would be grounded. Otherwise it's not a transmission line.

Another waldo appears, the reason for why I'm interested in this is because I've never seen any whip effect happen in a conductor, where a voltage grows larger and larger and larger the further it propagates the line. Also I'm a little bit certain that a directional antenna use the whip effect, though I'm not sure at all. And I would use it to turn pulses into ultra tall pulses to see if I can turn on MOSFET's ultra fast, much faster than what they are specified for.

EDIT1

Here's my understanding of how to design an "electrical whip".

I assume I need to shield it like a coaxial cable in order for it to act like a transmission line. And if I close the switch for a brief second => send a pulse, then \$V_x\$ should read something much higher than 5V. If it would've been a coaxial cable then it would've been close to 10 volt. Let's just say that the resistance at the end has the value 10k ohm. I'm mismatching the impedances on purpose.

It's a shame that I can't test this out right now.

EDIT2

Ferrite doesn't have high permittivity as far as I'm aware. Though it got high permeability
Copper powder got quite high permittivity because of the surface area and distance between the powder is small. Any conducting metal that is not iron or steel can be used as a powder instead for the copper powder I assume. Copper is chosen because of low permeability. The powder must not touch each other.

The electric whip got high permittivity at one end and high permeability at the other end.


texts:
I have made this circuit:

The idea of this circuit is to convert 0-3.3V(vdc0) input to 0-10V output. I have tested the circuit both in a simulator and in real life. In the simulator it worked. In real life it is another story..: I input 3.3V and get 10V output. But the output can only go down to 6V and not lower. Why is that? Is it something to do with some bias current from output through R1? I have tripple checked my wiring though..
I use a LM1458 as OpAmp.
Can anyone give me a hint to where i can find the answer?