texts: Transzorb for MCP73831 USB LiIon Charger?

texts:
The datasheet of MCP73831 (a small LiIon charger device) recommends a transzorb on the USB power input (VDD) for input over voltage protection. See Section 6.1.1.2.

Absolute maximum ratings for VDD is listed as 7.0V plus 4kV human body ESD and 400V machine model ESD.

Most transzorb/TVS/varistor devices that allows 5.1V, can be at 7V before the shunt current reaches 1mA and will specify a clamping voltage of 15-35V for higher currents.

Looking at some hobby devices using the same chip does not help. All these Sparkfun product designers clearly ignored the datasheet recommendation.

So what transzorb device did the datasheet author have in mind?

ADDED Apr 1, 16:

As an example of how the voltage waveform may look without any transzorb device during the USB plug-in event is shown below.

This is using a 5m USB cable to a standard USB wall adapter.


texts: How do I make a high signal last longer so my nodeMCU/Tasmota sees it?

texts:
Problem
I have a data input signal to a nodeMCU running Tasmota. It only works intermittently because the signal often isn't high long enough for Tasmota to sense it. So I need to find a way to make the signal high last longer.
Background
My apartment block has a 12VAC doorbell system, wired into my apartment intercom. I want to be notified when the street bell button is pressed. My solution is to wire the 12VAC into a short LED strip, adjacent to which is a photoresistor wired to an input pin on a nodeMCU running Tasmota. This works OK, but only if the bell button is pressed for longer than a second or two. If the button is pressed briefly, the LED strip lights, but Tasmota doesn't detect the brief signal high.
I am looking for a way in which the duration of the high signal can be prolonged (say from 500ms to 2000ms) so Tasmota doesn't miss it.


texts: I'm trying to wrap my mind around how capacitors work. I understand they store a charge and generally understand how but I don't understand how using them "smoothes" the flow of the charge. Doesn't, say a motor, drawing power from a charged capacitor do the same thing when drawing power from a power source? What does is mean that the charge is smoothed and how??


texts: What does 'output current' mean (PIR motion sensor)?

texts:
I have a PIR motion sensor and looking at its specifications it lists the following:

Voltage: 12V DC
Standby current: < 3uA
Output current: 5A

I am unsure of the term 'output current.'

If I'm not mistaken the outputted current will depend on the resistance of the load, so how can the current be stated?

Thanks


texts:
Hi,

This is a setup-hold time problem given in one of the digital designs book I am using.
In the figure(sorry for the poor drawing), a circuit schematic is shown and we have to find out the maximum clock frequency and whether any hold time violations occur or not.

The flip flops(shown with a CLK input) have a clock to Q contamination delay of 30ps and  a propagation delay of  80 ps.  They have a setup time of 50ps and a hold time of 60ps. Each logic gate(rectangular boxes with operation specified) has a propagation delay of 40ps and contamination delay of 25ps.

I am having a hard time understanding and solving this problem. The book has also provided information regarding setup and hold time constrains in terms of propagation and contamination delays such that

Clock period>=clock to Q propagation delay+combinational logic propagation delay+setup time

and

**clock to Q contamination delay+propagation delay>=hold time**

Can anybody help me with explaining these constraints and the problem solution.

Thanks.


texts: If I made an h bridge out of silicon controlled switches, would I still need a driver?

texts:
My question is relatively simple. If I arraged four silicon controled swithces, like the one here, to form an h bridge, could I drive it directly from the logic level? Since only gate to gate voltage will turn the switch on or off, it seems like there would be no need for a complex driver to handle high voltages between gates and sources or drains. Is this right?

See this question for some relevant information on silicon controlled switches.


texts:
An electrician friend of mine asked me if I could recommend a regulator to step down 125vac down to 118vac with a load of 2.5 amps. He would like 3 amps to be safe.
Normally I deal with low voltage DC and would use a buck-boost regulator to get a very consistent output voltage despite some fluctuation in the input and it has a trimpot for setup/calibration to prevent people from accidentally bumping it or messing with it easily. I don't know if there is a good equivalent for AC loads. Will something like this work, or is there something else that may work better? The load is non-inductive, it is a sensor, so the current draw should be fairly stable. I know we could achieve a roughly similar result with a potentiometer as a voltage divider or a resistor, but we're looking for something more stable and efficient that will adapt to some fluctuation.


texts: Application of Ohm's law / Conservation of Energy

texts:
I am taking my first Engineering Electronics class, Engineering Circuits I.  I seem to be understanding it, but this one example confuses me somewhat.

The simplest manifestation of Ohm's Law (V=IR) the circuit that consists of a single loop with one load and one fixed voltage source, vaguely makes sense given how I haven't had a chemical/quantum explanation of electron actions.

However, at first was assuming that the electrons coming off a 12 Volt Battery have more potential energy than a 6 Volt battery for example, because voltage is defined as joules per columb - and a columb is a fixed number of electrons.

Then we had this problem.  Mathematically, with Kirchoff's law, it makes total sense.

simulate this circuit – Schematic created using CircuitLab

The problem is to determine the total voltage coming off the battery, with the internal resistance of .1 Ohms.  Because the battery/alternator form a closed surface Kirchhoff's law applies and we have: $$V = 12+ [(i_b ).1 Ω]$$

But we know nothing about the potential energy of the electrons coming off of the Alternator, so this suggests that my "theory" might be wrong.

Could someone please be kind enought to explain this?


texts: Step down transformer vs Electronic voltage regulator for appliances between 220v to 110v

texts:
I recently purchased an Instant Pot 6 Quart with specs(Electric Pressure Cooker) from the US(outlet supply 110v) and would like to send it to a country that has outlet supply of 220v. The cooker is rated at 1000W to only run at 110v. This means that the usage of a step down transformer is a must.

I am looking at something like this. The 5000 in the image means it can take upto 5KW.

However, I came across these  electronic(SCR) voltage regulators that can do a step down function also. Pictured below is one such device

My question is the following: Do both these appliances convert 220v to 110v in the same fashion as far the usage is concerned(Off course the mechanism to achieve is different)? If yes, would it be ok to use any of the two for the pressure cooker? If not, why not?


texts: Are there examples of chips where comparing 2 against zero would be slower than comparing 1 against zero?

texts:
This question on StackOverflow goes like this which is faster - while(1) or while(2)? Asking which of two infinite loops is faster only makes sense if you ask it in sense "which can make more iterations per second".

The serious answers so far are "no difference".

Now suppose a compiler is dumb enough and generates a comparison instruction and so the code compares 1 versus zero in the first loop and 2 versus zero in the second loop.

Something like this for the first loop:

start:
    mov reg1, 1
    cmp reg1, 0
    je start

and something like this for the second loop:

start:
    mov reg1, 2
    cmp reg1, 0
    je start

This runs equally fast on some powerful chip like Intel Core i5 because the whole comparison is performed in hardware and effectively just compares any two 32-bit (or 64-bit) integer numbers in one operation and so any such comparison takes the same time.

What about some very low power very simple chips? I guess the comparison circuits on them could be designed simplified to be smaller at expense of speed.

Would comparing 2 against zero take same time as comparing 1 against zero on any reasonable chip?


texts: How to stop an electro magnet from sticking

texts:
I am using an electro magnetic door lock which I am powering with 12 volts.  It is switched on and off using a transistor array (uln2003.)  I have also included a flyback diode.  My problem is this: after I have switched off the magnet, there appears to be a lingering field that holds the door shut until it is pushed open.  It is not a strong field, and it goes away after the door is pressed open.  I need to build a circuit that can neutralize this field.  How?

My inexperienced mind is telling me that I need to send a short burst of current through the magnet in the opposite direction.


texts:
I'm very new to control theory and I am stuck at PID tuning.
I have a given Simulink model but I do not know the transfer function. I want to use a PID to provide new input from the output of the model.
Is it possible to tune the gains of the PID controller without knowing the transfer function?
Which methods can I use for this?


texts:
This is just a basic clarification I need.

I have this Power Supply

I always connect the red and black terminal to my circuit. I have never use the green terminal. I understand that the green terminal is Earth. But when would the need arise when I have to use it and how to use it?

Three questions I have :

The Black terminal is not necessarily 0V. If I adjust the voltage knob to 10V, it means the red terminal is 10V higher than Black terminal. So, the black is not necessarily 0V. Am I right?
When someone says isolate the power supplies, what does the connection imply?

3.I saw a few related questions asked here previously but unable to grasp the concept when someone says, "Don't tie the power supplies to a common ground when you are connecting two voltage sources in series". What does this mean and what would happen if we do so?


texts: Understanding DIN terminal block current ratings

texts:
I am making a control box for 12V 5 DC motors (~1.5 A total) and LED panels (~30 A). The system will pull ~30-35 A when it is running. Upon hearing of my project, a friend gave me some Allen Bradley 1492-J3 terminal blocks. I asked about the current rating and he said 'the amp rating is probably fine.'

But, I am not sure how to interpret the spec sheet. The spec sheet says they are rated at 25 A. Does that that 25 A rating mean that 150 A total could be pulled across all 6 blocks? Or does that mean the total when summing the current across all jumpered blocks can't exceed 25 A?


texts:
I have recently wondered if I could build some kind of useful and cool device, using some sensors, transmitting signal and doing something with it - I think people who answer questions on this site will know what I mean - some desire to tinker something.

So, I wondered about Internet and searched for some ideas, and found one that I would like to try to implement.

So, the idea is that there is a door, and when it opens and it is night time - the lights should be turned on for a minute or two, if there are no other lights on already. I think it is basic enough idea and I could get the experience of making something by implementing it. Now, I know there could possibly be already existing solutions, and I might be reinventing the wheel, but I want to try.

My question is - how do I approach this?

If I understand right,
1. there should be some sensor to detect if the door is open.
2. also another device which keeps track of the day time, so I know if its night or not.
3. some switches to operate with the lights - on and off states
4. some way to transmit the signal from switches and
5. something which will decide if the lights near door should be turned on or not

About the requirements - those things should probably be lightly powered so that they can run a lot of time without needing recharge (possibly using some AA batteries, or something smaller, what kind of power source could I use?), pretty much most of the time the devices should be automatically offline (maybe only switch on at night time?). Considering that I want it to be minimal in dimensions, so that I could easily install it anywhere I want - when the device is finished it should be somewhat compact (perhaps attachable to walls or something?), and of course - this shouldn't cost hundreds of dollars to buy and make, I mean its pretty much a small trinket?

So, given all this, my question is - where do I start? what should I look at? Can anyone describe the whole process to me? Including the final step of putting the electronics to some wrap, so that its inside some plastic and doesn't display the cords and patches and etc? Any advices and explanations are welcome.


texts: What is the difference between general purpose ADCs, Audio ADCs and video ADCs?

texts: An ADC merely converts an analogue signal to a digital one. Why then do we have special ADCs for audio and video application? What if one was to use general purpose op-amp in them instead?


texts:
On wanting to put on lamps I measured the conductors coming out of the ceiling - and they seemed a little off to me, so I wondered if anyone could tell me what it means.

I'm in Germany, and the conductors came in the newer color coded format brown-black-grey-blue-green.

Blue and green had no relative tension, as expected.

For the rest, look at the following table:

brown-blue   |  150 | 226
black-blue   |   65 |  94
grey-blue    |   34 |  48

grey-black   |   30 |  42
black-brown  |   49 |  75
brown-grey   |   77 | 120

The two columns are distinct measures for each of the settings of one of the light switches that appear to have had an influence on the voltages.

Bizarrely, I found no less than 4 light switches that had a significant impact (>20V) on the tension measurements.


texts:
Why is it difficult to find crystal oscillators that oscillate at 3.1 MHz and 3.3 MHz?
I searched for hours and couldn't find it.
Can anybody hep me on this?


texts:
I am trying to find a reasonably priced socket for a TQFP44 microcontroller but I am having a very hard time.

The only I found so far is this one:

http://uk.farnell.com/wells-cti/7010-044-6-08/socket-ic-zif-tqfp-44way/dp/1337653

I can get something similar for half the price if I buy it on Ebay from a Chinese seller, but it is still too expensive.

I think that I need the socket because the DIP version of the microcontroller is ten times bigger and there are no other surface mounted components on the board.  I am going to make only 4 boards, so I am investigating if I can avoid the extra cost of having the board assembled by the fab house.


texts: Forward diode characteristics not starting from zero Ampere

texts:
Why the current is not starting from zero, whats the diode characteristic when current is near zero?

Reading the datasheet for N-channel 60V MOSFET, I encountered this source-drain characteristic of the diode, but I don’t understand how to find diode on-state zero-current voltage here, as current doesn’t start from zero on characteristic.

Here you can find the datasheet for MOSFET.

EDIT:

I want to understand if the diode will conduct lower currents, comparing with other MOSFET characteristics, where you can clearly see how it behaves when the current is near zero.


texts: How does a transistor act as an amplifier considering energy conservation?

texts:
We all know energy cannot be formed from nothing.

So how does a bipolar junction transistor (BJT) — for example — amplify the base current by beta and outputs it to collector current?

Where is the “catch?” Is there somewhere else where were losing energy?


texts: How to charge 4 NiMh AA batteries with solar cell

texts:
I have a nice 6V solar panel and I was thinking to use it to recharge a 4xAA NiMh battery pack (nominal voltage 4.8).

Is it enough to put a series diode (0.7v) to drop the voltage, or do I have to use a current limiter?


texts: We are building a Raspberry Pi with 2 servo motors connected to one power supply. But whenever the servo motors are provided with a signal to power and then move, the raspberry pi's green light turns off, and then when the servo motors stop moving, the green light comes back on. We assumed that this is a loss in power but when we measured the voltage throughout the circuit, we found it to be a consistent 5 volts. Is there something else going on here? Does the raspberry pi's green light not necessarily mean it has power?


texts: What is Inter-Turn ShortCircuit Measurement - Coil function?

texts: I have a multimeter with Inter-Turn ShortCircuit Measurement - Coil function. The result is time value (10^-6 s). Could someone explain how the measurement works and why need a coil test adaptor for that .


texts:
I'm trying to make an accurate RGB detector, where the R,G, and B components of a sample are measured via the voltages
$$V_R, V_G, ~\text{and}~V_B,~\text{defined in the following circuit:}$$

Where the voltmeters are the ADC on the Arduino Due, and where the splitting into three channels goes on in a single component: The Hamamatsu S9702:

The problem is, when I vary the resistance in one channel (from 10 megohms to something else), the readings in the other channels are vastly affected. For example, here is some data from a blue LED source:

Since there is cross-talk (i.e. the voltage in any given channel is dependent on the conditions in the other channels), does this mean I should scrap this design?
Or is this design still okay, provided that the resistances in each channel are precisely the same?
Is there a version of this circuit where the channels are truly independent (keep in mind that the RGB diode has 4 pins, and thus only takes in one voltage source)?


texts: Using Thévenin's Theorem / Voltage Across Independent Current Sources

texts:
I've been attempting this problem regarding the usage of Thévenin's Theorem to find the value of Io. I am able to get the correct Thevenin Resistance, however attempting to find the Thevenin Voltage has been confusing me. When breaking the circuit at the 4kOhm resistor I tried to do a kVl loop around the bottom left square containing the 5V source and the open voltage from opening the resistor and got a value of 5 which is incorrect. I'm confused as to why it is incorrect and am wondering if it is because there is a voltage attributed to the 2mA independent source which I am not considering. I have attached the problem, any guidance would be greatly appreciated.

Thank you!


texts: How can we find transfer function of this n/w

texts:
How can we find the transfer function $$\frac{E_0(s)}{E_1(s)}$$ of this RC network

simulate this circuit – Schematic created using CircuitLab


texts: ESD Anti static mat Grounding and AC volts

texts:
I have an rubber ESD anti static mat on my bench that came without the snaps. I installed 2 snaps, one on each side of the mat. I connected the ground wire from the snap on the mat to the ground in the wall outlet (the screw in the middle). The wire connecting to the ground in the wall has a 1mohm resistance and the wrist strap also has a 1mohm resistance.

I'm performing tests to see if the setup is working properly. Having my multimeter set to AC voltage, I connect the black lead to the ground on the mat, and I hold the other red lead in my hand. With the wrist strap off I read about 10V. When I have the wrist strap on, it reads 2V instead of 10V. I assume this means ground is working.

My question is why isn't the voltage dropping down to 0v instead of 2v when I have the wrist strap on?


texts:
I am using a P-Channel MOSFET to build a buck converter and change 12VDC, 2A (from a 12V battery) to 5VDC, 2A (for cell phone charging), should I use a MOSFET rated for 20V, 2A or -20V, -2A?

I am new to this, so sorry for the basic question. A simple one word answer will do, don't trouble yourselves too much with an explanation.

Thanks!!!!


texts: What role does the capacitor and the resistor play in the following circuit?

texts:
I opened up an LED light bulb at my home and sketched its circuit diagram as follows:

I don't understand what the initial 470n capacitor connected to the live wire and the final 100ohm resistor connected to the neutral wire does.


texts: Plateau in collector-emitter voltage during BJT turn-off

texts:
I have the following circuit that uses a NPN transistor as a switch:

I've built the circuit on a PCB, and while testing I noticed the following plateau in Vce (blue trace) when Vb transitions to zero (yellow trace):

Does anyone know what is causing this? It never showed up in any of my simulations with LTSpice.

I've played around with including a BAT54 Schottky diode between base and collector to prevent saturation, but the odd plateau remains.


texts: Why do we not get shocked by neutral wire and how can it behave as it does?

texts:
I read some articles and watched videos regarding 1 phase and 3 phase ac. And later found that for most home appliances we need 1 phase ac.

Then I came to know about live and neutral wires. Few articles said neutral wire (blue) has 0 potential. And live wire (red) has high potential. Neutral wire is to return the current back to source.

Another thing they said is since current is ac, the bulb in our home keeps dimming and lightning very fastly and it can't be noticed.

(I also read about earth wire. That was the thing that lead me to this question but I'll ask about that later)

All these things gave me 3 doubts for now.

If neutral wire returns the current, the same which was in live/red wire, why doesn't it give shock?
Would it make any difference if you connect the bulb using 2 different methods as shown in image? (I have assumed a blub is connected this way. There are two points, one for in and one for out)
If current keeps changing its direction many times a second, that means current should keep flowing from red to blue, blue to red and continuously. How is it even possible to flow current from blue/neutral wire? Where would current come in blue wire? From Earth?

Okay these might seem too broad, but I believe these are very much related but I have separate doubts since I don't understand the concept fully.

PS: Simple and not very scientific language would be appreciated :)


texts:
I'm newbie in electronics, but I want to learn some basics things.

I have a 12V DC output (from a charging/discharging PCB Lipo battery), and I would like to stabilize it to run a mini-amplifier (Veleman Kit MK190) and 2x2W speakers. For now, I have lots of parazites.

I have an oscilloscope, the signal is this one, with theses scales:

horizontal: 0.5 µs / div

vertical: 20 mV / div

So Delta V = 60 mV

My question: What is the best way to stabilise it, to have a sound without parazites ?
Does a L7812 regulator a good solution ?

In this case, what should be the diagram I could use ?

Can I add a capacitor to filter the signal ?

Thanks

Edit: To precise my question, I havn't the datasheet of the battery, but a photo of the PCB:

I have plugged the oscilloscope in the 12V output.
The battery can also deliver 5V with the USB port.
You can see a displaced capacitor, because I need space...


texts: Derivation of Feedforward Gains for current mode control in CCM converter

texts:
I recently start to read the dissertation of Dr.Ridley, A New Small-Signal Model for Current-Mode Control and I am stuck on a basic equation.
First we have the function of the inductor current for constant frequency control :
$$
R_i<i_L>=v_c-DT_sS_e-\frac{S_fD'T_s}{2}
$$
Which is fine, I get it, then the equation below can be describe :
$$
D=\frac{v_{off}}{v_{on}+v_{off}}\\
D'=\frac{v_{on}}{v_{on}+v_{off}}\\
S_f=\frac{v_{off}R_i}{L}
$$
Normally, if I substitute theses equations in the previous function and perturbing the ON-time voltage, I should get this :
$$
\frac{<\hat{i_L}>}{\hat{v_{on}}} = \frac{DS_eT_s}{V_{ap}R_i}-\frac{D^2T_s}{2L}
$$
But I can't. I guess I'm missing something but I don't know what. Do you have any idea ?
EDIT :
Here's what I can get :
$$
<i_L>=-\frac{DT_sS_e}{R_i\hat{v_{on}}}-\frac{D(V_{on}+\hat{v_{on}})T_s}{2L\hat{v_{on}}}
$$
\$T_s\$ is the period of the switching frequency, \$D\$ the duty cycle, \$R_i\$ the current sense resistor, \$v_{on}\$ voltage when switch is ON, \$v_{off}\$ voltage when the switch is OFF, \$v_c\$ is the control voltage. As for \$S_f\$ it's the current slope inductor and \$S_e\$ is the slope compensation of the voltage control as seen below :


texts: PMOS and NMOS Current loads in Common Source Stage

texts: I am new to the concept of Single Stage amplifiers design using CMOS. In that, I came across a concept of using current source as loads in design of Common Source Stage, where it was mentioned in a statement that, the PMOS current source as load is generally preferred than using NMOS current source as load in Common Source stage. May I know the actual reason for this statement. If there is any reference available related to my question, kindly share it.


texts:
I set up an Octopi system for my 3d printer. I would love if the Pi turns on together with the printer.
The printer PSU outputs 24 V DC and has a couple extra terminals. So to save a plug I would love to have those connected.
I don't really want to buy anything, but I have a lot of electronics laying around, so if there's a circuit I could build to achieve my goal, that would be greatly appreciated.


texts: Driving 74HC logic with sub-nano second clock reference

texts:
My goal:

I am trying to phase lock a 74HC-based digital circuit from a clock reference at 10~15MHz pulse repetition rate. The pulse width is around 400 picosecond. The peak voltage is sometimes below 700mV, depending on the coax cable length.

I don't actually mind the shape of the clock; even a conversion to sine wave like waveform is accepted, as long as I can drive my 47HC based electronics from this weak pulsed trigger. Should I look for designs to pre-condition the clock reference? I generally aim at a low-cost solution, else it would be an over-kill for my digital board (~$50).

Circuit diagram of the clock reference

The clock source is generated by a photodetector. The following shows the internal circuit layout provided by vendor. I cannot modify the circuit inside the photodetector as it will void the warranty terms.

Things I tried:

1. 74HCU04 amplifier

The following layout from this blog removes the pulses instead of amplifying it:

simulate this circuit – Schematic created using CircuitLab

2. NPN class-C amplifier

I observe ringing at around 300mVpp but I cannot see the pulses:

simulate this circuit

[EDIT] Things achieved so far based on answers

George Herold reminded me that my current-sourcing signal needs to be converted to a voltage before amplification. So I now connect the 50Ohm termination resistor in series with my amplifier gates.

As I only have HCU04 at hand, I tinkered with the capacitor-resistor combination to amplify the signal at multiple stage:

simulate this circuit

In stage 2 and 3, I have to AC-couple the signal so that it can be biased at VCC/2 at which amplification effect is the largest. Otherwise the baseline of the pulse signal will be drifting away to either VCC or GND where there will be no amplification. The 4th stage works simply like an inverter to give me a rising edge.

Is there any design rule for this? I am afraid the result may not be reproducible on PCB layout.


texts: CPU considerations for PCB software (routing) when purchasing a new computer

texts:
My company uses Altium Designer for PCB design and the most CPU intensive operation seems to be the autorouting.

My question is, when considering a new computer, would it benefit autorouting algorithms more to have multiple cores of a given speed, or fewer cores of a higher speed? Does Altium's autorouting take advantage of multiple CPU cores?

Specifically I am considering laptop processors but this question could easily apply to desktop processors as well.


texts: Designing implementation-inspecific PIC32MZ communication classes in C++

texts:
Alright everyone, that title may seem like a significant amount of technobabble, so let me explain what I'm trying to do.

I'm starting to break into the PIC32 family, specifically the PIC32MZ series, namely because I'm starting to want to do things that I want more horsepower for than an AVR can deliver. I've been reading a bunch of tutorial docs and source on the subject, but I figured I'd bring this question here.

What I'm trying to do is develop a set of classes for the communication interfaces in C++ such that they are unit-inspecific; that is, a generic class that is initialized with the number of the communication interface unit; essentially "one set of code for any number of interfaces". Let me give you an example.

We know from the datasheet that the PIC32MZ family has 6 4-wire SPI modules. This example, while it (presumably) works, it has a number of things that I consider undesirable for my uses:

It's in C. I want to use classes to help with my data management, so preferably I'm looking for a C++ solution. Obviously, it'd take me all of ten minutes to rewrite this code, but see the next point.
It's specific to SPI2. This means I'd need an individual class for each of the six SPI units, even if I only need one or two. What I'd like to develop is a unified class for SPI, such that I can call one class and declare the unit number (1 to 6) in the constructor and have it initialize the appropriate one. Basing off the above example, the constructor would look like so:

SPI::SPI (uint baud, uint u_num)
{
     // Some discrimination of what u_num is
     // Setup
}

Things I've considered, but thrown-out/decided against/unsure if feasible or how to do:

If/else/switch statements in each method. This is the obviously easiest of all possible routes, but also the dumbest and the most sub-optimal. Every time the method calls, it would have to evaluate which unit to assign the parameters to which is wasted time.
Function pointers from Microchip functions into arrays for calls. So, SPI1-6 functions such as configure, send byte, etc. would map into an array, when the class method calls it plugs the unit number (stored in a class variable) into the array and pumps the parameters in to the function referenced by the pointer table.
Macros. Using the register macros provided by Microchip somehow to my advantage, although I have no idea (not afraid to say that one) how I would use that or to my advantage. Again, the gut feeling is it'd have to be some sort of pointer table.
Raw addresses. I seem to remember that the datasheet gives the addresses for the registers in the memory space, although it's hard to draw a reference to them right now on demand. I believe they were virtual addresses - my main issue with this is that I don't have a clue how to leverage virtual memory from a high-level context (I've always understood that the OS and CPU manage virtual memory to physical address mapping, but how that translates up the totem pole I have no idea of), and so I wouldn't have any idea how to make the class work. Essentially, if I could figure it out (providing this was feasible), I could figure out the association (offset) between say, SPI1 registers and SPI2 registers and make the class methods auto-apply that offset depending on the unit class variable.

EDIT: Found the SPI register map along with virtual addresses, apparently starting at 0xBF821000, although it's of little comfort so far.

Thank you if any of you can help.


texts: Automotive power steering unit connector identification

texts:
I would like to request some help to identify the following connector (at least the manufacturer and connector family type):

located inside the Toyota Camry 2018 Hybrid Power Steering Rack Pinion (marked with 2.)
it is connecting the torque sensor with the EPS motor
the type of the power steering rack pinion is: JJ501-003031

Thank you in advance,

Connector marked with 2.:

Front view:

Side view:

Identification sticker:


texts: How can I determine a resolution of 4:2:2 YCbCr image?

texts:
I fetch data from 420 TVL camera, and now I just want to see this image, the only thing I need is resolution to draw it on my screen. How can I determine this?

BWP M420MD -- camera,
I'm getting DCMI data from decoder TVP5150AM1


texts:
As seen from the question above, I'm required to calculate \$I_C\$ for both cases. Why am I not able to get the answer by using the formula $$I_C = I_S  e^{V_{BE}/V_T}$$ ?

I was only able to get the answer through finding \$V_B = 2.5\text{V}\$ and assuming \$V_{BE} = 0.7\text{V}\$. \$V_E\$ is then \$2.5-0.7 = 1.8\text{V}\$, and with this value I can easily calculate \$I_E\$ and subsequently \$I_C\$.

But using the method above, I'm not able to get the answer for part (b), as for the case of \$V_B\$, \$R_1\$ is still equal to \$R_2\$, resulting in \$V_B = 2.5\text{V}\$. I'll still get the same answer.

I recall my lecturer saying that the equation $$I_C = I_S  e^{V_{BE}/V_T}$$  can only be used when \$V_{BE}\$ is to be found through iteration. I can't remember the reasoning behind though.

Hope you guys could clarify on this.


texts: AC fuse sizing and type for a power entry module

texts:
I have this power entry module with a 6A rated current. The module needs two fuses to be installed. The exact model is:

FN 286B 6-06 and at the bottom of page 2 the rated current is given as 6A at 40°C and 7.2A at 25°C.

The data-sheet is not recommending the factor for the fuse current sizing and the type of the fuse. It only mentions the dimensions of the fuse.

I couldn't find consistent information about this. I thought a 10A slow fuse would be too big for this. What current rated fuse and type would be suitable roughly for this module? Is there a rule of thumb?


texts: Theorem For Logic Reduction to LUT for FPGA

texts: I would like to know if there is any theorem that states that any logic can be broken down and simplified such that we can encode that logic in the form of LUT that can be deployed in FPGA.


texts: Is this bistable 1 coil power relay implemented correctly?

texts:
I recently sourced a schematic where one of the functions of the planned board is to latch a high current line via a power relay. The relay is needs to be switched on and off occassionally (e.g a few times a week). I understand the basic operations of latching relays but my electrical knowledge is quite limited.
Here is the circuit in question:

[edited]
Case 1:
When BAT_RELAY_RESET is set to 0 and BAT_RELAY_SET is set high for 100ms every second (suggested by relay supplier), I expect the result the relay should latch, i.e.
But I see the same pulse on both scope channels with probes at A1 and A2.
Moreover the pulse is actually inverted, going from high to low (more like a 900ms) pulse.

Case 2:
When I do the inverse, the pulses have the right order, but the voltage drops by a lot.
I was expecting the circuit which is symettrical around A1 and A2 to provide the inverse results in both cases.
GPIOs pulses from the microcontroller look ok. I'm not really familiar with operating such relays. Does anyone have an idea or suggestion? What change to the existing circuit could lead to a fix?


texts: Why this code wasn't written in a much simpler way?

texts:
I have came across a question while working on assembly language. Here is the question:

Assume that bit P2.2 is used to control an outdoor light and bit P2.5 a light inside a building. Show how to turn on the outside light and turn off the inside one.

Solution given:

SETB C            ; CY = 1
ORL C, P2.2       ; CY = P2.2 ORed w/ CY
MOV P2.2, C       ; turn it on if not on
CLR C             ; CY = 0
ANL C, P2.5       ; CY = P2.5 ANDed w/P2.5
MOV P2.5,C        ; turn it off if not off

I just felt like it would do just the same job to code:

SETB P2.2
CLR P2.5

What's wrong with that?


texts:
I recently started to start working on a project where I started using a half-bridge to turn on and off a device that normally plugs into a wall outlet (120 VAC, 60 Hz). In the future, I am looking to use two of these in an H-Bridge configuration, but for simplicity, I am just using a half bridge for now.

As I was designing the circuit, I started to think of a potential issue regarding the power-up state of the half bridge. When the device is powered up, and the biases for the gate driver / half-bridge are brought up, I was concerned that I might not know the ON/OFF state of each FET. To combat this, I was considering adding a relay to the circuit supplying the voltage to the half-bridge so that I can let all of the low-voltage control circuitry power up, and after I can establish the state of the half bridge, then I flip the relay to supply the voltage to it as show below (please ignore the values on the FET's):

Here is what I was wondering:

Is this really necessary? Is this dangerous to do, as the FET's have some drain to source capacitance, so could this potentially temporarily cause a surge on the 170V rectified AC wall voltage signal? I considered trying to solve this with either a choke/low valued resistance on the 170V input, but again if this is a non-issue, than I won't worry too much. I have a prototype of this device made, and I powered up without the relay with no issue, but I want to make sure I was not just getting lucky, and now I am just waiting for this thing to fail.

If it helps at all, these are the gate driver and FET's that I am using:

FET - IRLS640A

Gate Driver - FAD6263M1X

Thank you so much!


texts:
Could someone please direct me how to interface with this chip? I am a total newbie in electronics, and after buying this chip, well, i have absolutely no idea how to connect it.

The chip has an USB port, so i was sure that it needs to be connected through it to a PC (perhaps with some jumper setting). I couldn't find a double male usb-a cable, so i bought parts for it with the chip. The USB parts didn't reach me, so i was going to use some old mice and printer cables to salvage the parts - but that made me think - is it really a good idea to connect it like this? I'm just trying to connect it and check what happens - hopefully some hint on how to go from there, not a fire. Hell, i don't even know the pin order for such a cable.

I bought the V2DIP1 hoping i could cut down costs of my robot i decided on a FTDI chip instead of an arduino ADK to get a serial connection from an android device to an Arduino or directly a H-Brdige, or a button/sensor etc. My reasoning was that the ADK devices have and FTDI chip internaly anyway (they do, right?), and i have a arduino uno already.

So, what i need from this chip is at least to make some connection to android (or even a PC, for now) and set/read some pins on/from it - any hints on how to do this, please?

The chip i bought: http://www.tme.eu/en/details/v2dip1-48/ftdi-modules/ftdi/

An FTDI tutorial on how to attach to android (but the board is different :/): http://www.ftdichip.com/Support/SoftwareExamples/Android_Projects.htm


texts:
I'm designing a PCB with Altium 14 composed by 4 SMT headers (2 on top, rest on bottom) but everytime I try to move them it puts the cursor on coordinates -4699.664,49086.331 (way, way far from my design) and I have no idea why is that happening, so I can't move the objects.

Do you know why this is happening or at least know another way to move the object?


texts: Difference between ideal and practical ammeter?

texts:
What is the difference between the ideal and practical ammeter?

To be more precise, here's my task:

I do not need a solution to this. Just looking for a clear explanation between practical and ideal ammeter, because I've only encountered the latter one so far.

Thanks.


texts: Using Metal thumb tacks to trigger events

texts:
I am new and curious to electronics,
The below video shows a circuit bent keyboard using a keyboard made of thumb tacks to control the note input. I would love to know how this was done.

The video: https://www.youtube.com/watch?v=y7G_68mkrs0

Extra information and build notes: https://imgur.com/a/qOT5Y

Is he using the tacks to complete the circuit somehow?
Is he using his fingers to change the resistance, I have no clue.

Thank you, any help would be passively appreciated.


texts: Problem figuring star delta starter circuit

texts:
I know the basic functioning of star delta motor starter configuration but kind of stuck on my current project which uses old L&T starter panel. I can't figure out the terminals like A1, A2 (coil power terminals), NO (used with push start the coil) etc. The panel has two push buttons

Green >> mechanically presses the starter stick

Red >> mechanically presses the stop stick

I am attaching pictures of panel, please help me figuring out the parts used and terminals. I tried searching on internet but can't get much details of these kind of contactors.
Edit: Sticks marked in last photo might be opposite


texts: What does "load" mean and what are the different types?

texts: What are all the different types of "load" and what are the key important facts to know about each?


texts: Analog circuitry for measuring capacitive touch

texts:
I'm interested in adding capacitive touch input to a project I'm working on. Ideally I would like a tapered shape so that a finger can slide up as if it's a mixing desk fader or something like that.
However, everything I read about capacitive touch input online involves using an ADC/microcontroller to digitise the value, then use software to determine the output. I am wondering if there is any circuit which can achieve this without any code: a capacitive touch input, which creates a voltage proportional to how much capacitance* the finger is exerting on it.
So, is there an analog circuit which can achieve this without any microcontroller?
*The capacitance varying through either the distance of the finger from the sensor, or some kind of tapered sensor as I mentioned. I'm aware that external factors could affect the capacitance too.


texts: Unable to send data to Thingspeak using ESP8266 and STM32 Nucleo

texts:
I am using ARM's mbed compiler to program my STM32 Nucleo. I am also using an ESP8266 as my WiFi module.

My connections are as such:

Rx of the ESP8266 is connected to D8 on the Nucleo.
Tx of the ESP8266 is connected to D2 on the Nucleo.
Gnd of the ESP8266 to the gnd on the board.
All other pins of the ESP8266 are connected to 3.3V on the Nucleo.

The following is my mbed code:

#include "mbed.h"

Serial esp(D8, D2);
DigitalOut myled(LED1);

void flush(void) {
  while (esp.readable()) {
    (void)esp.getc();
  }
}

int main() {
  esp.baud (115200);
  char server[]="GET /update?key=NR************2Z&field1=7";
  flush();

  esp.printf("AT+RST\r\n");
  wait(2);

  esp.printf("AT+CWMODE=1\r\n");
  wait(3);

  esp.printf("AT+CWJAP=\"Harsha\",\"*****\"\r\n");
  wait(3);

  esp.printf("AT+CIPMUX=1\r\n");
  wait(3);

  esp.printf("AT+CIPSTART=4,\"TCP\",\"184.106.153.149\",80\r\n");
  wait(3);

  esp.printf("AT+CIPSEND=4,%d\r\n", sizeof(server)+2);
  wait(2);

  esp.printf("%s\r\n", server);
  wait(3);

  esp.printf("AT+CIPCLOSE\r\n");

  while(1) {
    myled = 1;
    wait(0.1);

    myled = 0;
    wait(0.1);
   }

  return 0;
}

I am able to connect to my WiFi hotspot which means there is no problem with the connection. But the data I pass is not updated in Thingspeak at all. I have also tried it including HTTP/1.0 and HTTP/1.1 in the 'server' string, still nothing. Am I missing something?


texts: Inverted Op Amp for Current Sensor Output

texts:
I'm having trouble understanding why the following circuit uses the inverting configuration rather than the non-inverting configuration for amplification.

This design is from the Sparkfun Current Sensor Breakout (Low Current version):
Sparkfun Low Current Sensor Breakout

I do not understand why it can be said that the gain is +2x to +22x. Shouldn't this be -2x to -22x gain since it is an inverting op amp configuration. A = -R1/R2 ?

After doing some reading, the only reasoning I can come up with is the fact that the input impedance in the inverting config is much lower and thus would affect the sensor measurement much less than in a non-inverting config.

I do not understand how this inverted output is going directly to an ADC pin in their hookup guide found here: Hookup Guide for Current Sensor Breakout
Does the ADC only care about the absolute value?

It is not re-inverted again in firmware either. I think I am missing something extremely trivial and it's bothering me a lot. Also, in my intended application, I would eliminate the trimpot on the positive input of the op amp and have a direct reference to ground, since I am only interested in sensing positive direct current that my application will consume from a wall adapter.


texts: Measure temperature of IC/Microcontroller

texts:
I want to measure the temperature of IC/Microcontroller. There is no On-die temperature sensor to measure the heat. I need to check how much hot the controller gets. The LM35 or DHT11 Temperature will not work as they sense ambient temperature not the surface temperature. How about thermocouples or Thermistor NTC?

Any other device for measuring the temp of IC?

This is the device OP is referring to:


texts: What sort of soldering iron tip do I need for very fine PCB work?

texts:
I have a very fine PCB (illustrated in an answer to Soldering with a delicate looking board) but I have discovered that the screwdriver like tip I have seems to be too clumsy to clear solder from so tiny a hole.

If I go and buy an alternative tip what am I looking for?


texts: How to measure output of the ultrasonic transducer?

texts:
I have found a test circuit for the ultrasonic transducer. How do I measure the output distance sensed by the ultrasonic transducer using my Arduino Uno R3? Please help.

I have attached the test circuit.


texts: Using a US/UK voltage transformer at low end of appliance power range

texts:
I've purchased this from ebay, and the official vitaclay product spec page for the model indicates a power consumption range of 500-600W.

Transformers appear to come in either 500W or 1000W, but nothing in between. What does it mean that the product spec indicates a range of 500-600W input? Does it mean that it consumes different amounts of power depending on the functionality that is used with it? Can I use a 500W transformer with it? (For example, this one?) What happens if it attempts to draw power at a rate exceeding 500W?


texts: SMPS powered DC motor inrush current problem

texts:
I stumbled upon a problem when connecting a DC motor to a SMPS. It's a 20W AC/DC converter with an 12V output that powers some 12V DC motors the processor and some LEDs. I needed to speed up the most powerful of the motors so I added a boost converter on the lines of the motor to raise the voltage to 17 V. If I raise the voltage above 17V I encouter a problem when switching the motor on. Apparently the inrush current is too great and the SMPS shuts off and restarts, restarting the processor with it. The winding of the motor has a resistance of 15 Ohms and the running current of about 200 mA.
After searching the web I found 2 possible solutions to my problem:

LC filter after the SMPS where the C1 serves as a bank for the inrush current. The L1 is there to not cause the inrush problem when charging the capacitor C1 at SMSP power up (I have no idea about the right values for C1 and L1). The R1 represents the resistance of the motor winding (15 Ohm).

simulate this circuit – Schematic created using CircuitLab

An NTC thermistor on the line of the motor. I'm unsure about the exact one to use as I am worried that the characteristic is not steep enough and would either have too low resistance when starting or too high resistance when the motor is running and thus slowing it down.

Would it make sense to use the combination of the two solutions?
How can I determine the appropriate values for L1 and C1? I have no idea how high the current peak is and how long it lasts, all I know is that the motor has virtually no mechanic load connected to it and can start easily.
I hope there is enough information, otherwise I'll try to add whatever is needed.


texts:
Can Anyone help me to identify this board to board connector?
7 springs connector on top and 8 on the bottom.

 answer
Found a Korean company producing it. Thanks.

This is the plug on the other end...

Connector with Ruler for size reference..


texts:
I just attempted my first project with an LCD, and it did not go well. I am hoping to get some advice on how to prevent this from happening to my next LCD.

On the first night everything seemed to work fine - the LCD was bright and clear. On the 2nd night I suddenly noticed smoke coming from the backlight LED+ pin (pin 15).

I measured the current going through the backlight and it was something like 80mA. Seems very high to me...

I examined the other side and could see melted plastic:

The datasheet says that no resistor is necessary for the backlight, but I tried hooking up a 12 ohm resistor anyways. This stopped the smoke, but caused the backlight to flicker. I found another datasheet for a similar LCD, and that one required 4.2V instead of 5V on the LED. I tried doing that as well by hooking up the LED through two diodes in series, but this setup continued to smoke. I measured the current again, and now it was drawing 600mA! I am currently running the LCD w/o the backlight, since it now starts making a boiling sound immediately when I connect it.

I have purchased this LCD here:
http://www.adafruit.com/products/181
http://www.adafruit.com/datasheets/TC1602A-01T.pdf

And hooked up the backlight in accordance with this tutorial:
http://learn.adafruit.com/character-lcds/wiring-a-character-lcd

Note that both the tutorial and the datasheet hook up the LED directly to +5V, which is exactly what I did.

So, what could have gone wrong? What precautions can I take to prevent this from happening again? Any suggestions would be appreciated!

Here is a video that shows a bit more of the setup and the smoke: http://www.youtube.com/watch?v=Wdqyi4hqlMw

Thank you!


texts: How to enable the 12V output in a storageworks HS0550 psu?

texts:
[update: added trace of pins]

I needed a chunky 12V power supply, and I have found one of these HS0550 which is rated to supply 12V @ 45.2A according to the spec;

It was surplus from an old HP StorageWorks XP20000 system. However none of the pins on the back seem to be giving +12V relative to what I think is GND. (there are pins with +3.6v and +4.68v)

Googling the product code suggests it's manufactured by Hitachi as a "HITACHI 5529219-A USP-V DKU POWER SUPPLY";
http://www.serverworlds.com/hitachi-5529219-a-usp-v-dku-power-supply/

Unfortunately, I can't find any docs on either the code 5529219-A  or "HS0550"

I don't recognise the pinouts, but those connectors are actually adapters and can be removed, which gives 5 blocks of 6 pins;

I presume that these supplies use something similar to the ATX power supply standard, and require shorting across pins, or some other signal to enable to the 12V line;
http://www.techpowerup.com/articles/other/22

But I can't find any explanation of what power standard this PSU is using...

Some general troubleshooting seems to suggest that the unit is working, as I can find 9v at some points on the board when powered up, and there is a test point which is reading something like 418v DC;

Here are some shots of the top and bottom of the board;

I've traced out the pins, and the brown trace looks like it should by the one carrying 12V. I think the blue trace is the signal for connection pin.

There are 3 opto couplers in the centre which I think are being used to switch on the main 12V circuit. 2 are connected to one daughter board, and then the other to a separate daughter board with the 12V level adjustment.


texts: how to remove dialshock 2 ribbon flex board?

texts:
my dualshock 2 has a connector to the ribbon board and looks like this
connector

can someone tell me the proper way to remove the flex board from this connector while leaving the connector in working order?


texts:
I'm trying to generate a 24MHz clock signal from the STM32F407 running at 168MHz. This signal would then be used to clock a USB hub IC (Microchip USB2513B). From the hub's datasheet, I learn that the clock frequency should be 24MHz ±350ppm and the jitter less than 100ps RMS.

My question: would a clock signal generated by a timer fit with these specifications? I know that I can generate a 24MHz signal using a period of 7 (168/7=24MHz) but I wasn't able to find anything about timer accuracy and jitter in the STM32F407 datasheet.

Another potential option would be to use the Microcontroller Clock Output functionality but I would have to lower the system clock to 120MHz since the prescaler is limited to 5 for this feature (120/5=24). Again, I couldn't find any information on the accuracy and jitter of the MCO.

Third option would be to use a 24MHz crystal as a source for both the STM32F4 and the USB hub. If possible, I'd like to keep the 8MHz crystal I have now.

Does anyone know more about timer precision on the STM32F4 series?

EDIT: I found the main PLL jitter (15 or 25 ps RMS) but nothing about the accuracy.

I'm not sure if my reasoning process is sound, but assuming I use a 8MHz crystal as oscillator for the STM32F4, I guess that at best I can expect 3x the accuracy/jitter of my crystal?


texts: Video RAM: How to create a shared bus for processor and VGA controller

texts:
I have a discrete video controller which reads a image from SRAM. The image should be written by a CPU. So I designed this circuit.

I use two display RAM because I want to use double buffering. So the CPU should only write to the inactive memory.

Is there any option to simplify this circuit, because I think this solution is very complex (especially when I design the PCB).


texts: A mechano-electro-magnetical control circuit

texts:
I came up with the following mechano-electro-magnetical control circuit. The system as depicted here is in equilibrium, i.e. the upper spring s1 is relaxed , the upper circuit is closed (C1 producing a magnetic field), the lower spring s2 is slightly stretched, the lower circuit is open  (C2 not producing a magnetic field).

I wonder how this system behaves when m2 is driven into the direction of the magnet/coil C1 by an external force.

Eventually the magnetic force will exceed the force of spring s2,  m2 will jump and close the contact.  C2 will create a magnetic field that pushes away m1, opening the upper circuit. The magnetic field created by  C1 will vanish,  m2 will be drawn back by  s2, and so forth.

Possibly, a limit cycle will be reached, possibly the stable ground state will be reached, depending on parameters like spring and coil constants, the voltages Vi and resistances Ri.

  Can this system be solved analytically?

Additional question:

  Has such a circuit been realized and is acutally used in any context? Any references?


texts:
I am quite new in this field and I started recently by reading the first books in electrical engineering where I learned the concept of current, voltage, impedance, reactance (inductive and capacitive).

I was reading yesterday about coaxial cables where the conductive elements are the core and the shield. I though that the the core and the shield are the "extension" of plus and minus poles of the power source (that in the ac source alternate).

The reason I am asking is that the shield is typically connected to the ground ("The cable is protected by an outer insulating jacket. Normally, the shield is kept at ground potential and a signal carrying voltage is applied to the center conductor."). So somehow I am a bit confused on if I understand precisely how one can think a coaxial cable being a part of a simple RLC circuit schematic.


texts: 24V Isolated digital input protection TVS

texts:
I am working on creating 24V industrial Grade(Like Siemens PLC I/O) Digital Input circuit,The micro will use the 3.3V supply.
circuit works with TWO input signal one of them is 24V industrial "24V_sig" and should be protected ,the "5V_IN" is from Tac switch. (D1,D2 and D5,D6 In OR Combination).

I have some ideas but I don't know do I think in right way.
Here is two circuit that i design :

1-Which way of protecting is better, first or second?

2-in first circuit,is it necessary to add D4 when there is SMBJ28C there ?

3-Should i connect Common to GND ?


texts:
Never used a BIOs programmer before. Wondering what are they for.
For my current project, I need something to configure my PLL chip, which has an SPI interface.

I already have the evaluation board for my PLL chip but I need something to program it. I don't know if a universal BIOs programmer like a Oumij EZP2019  example one would do the job. Does anyone has suggestions? how would one usually program such IC?
Thanks


texts: I'm trying to learn how AM radio communication works. If I understand correctly, an AM radio signal transmits on a fixed frequency, using the amplitude of the wave to transmit the frequency of the sound. However, this only carries the frequency of the source sound, not the volume. So if you're transmitting voice, how is a whisper quiet and a scream loud? Why wouldn't they be the same volume?


texts: We have all heard the buzzing sound that your speakers makes when you use your phone near your radio or amp. My question is why does one hear this interference if GSM operates at ~800-900MHz which is 40x higher than the highest humanly audible frequency?


texts: Confusion with meaning of low and high impedance sensor

texts:
Regarding an excerpt from this text:

  Some accelerometers feature an integrated electronic circuit which
  converts the high impedance charge output into a low impedance voltage
  signal.

What is meant by low/high impedance here? Output impedance?

Why is charge output a high impedance and what does it mean that it is converted to a low impedance voltage signal? Can you give an analogy or basic circuit example to understand these? And why does it matter?


texts: Can I connect DC GND to AC earth? If so, what is the purpose?

texts:
I am trying to use the circuit shown below in the picture.
In the circuit, from the AC supply, the PE is connected with the ground symbol. I assumed I need to connect PE (protective earth) with the DC Gnd (-ve terminal).
Is that correct?


texts: How should I size the transistors in the class AB linear amplifier

texts:
If I want to design a class AB linear amplifier as the following one, how should I determine the width of the pmos and nmos?

Class AB amplifier specifications:
Vdd: 6V
Input: 0.5V to 5.5V
Output voltage 0.5V to 5.5V
Output current: -450mA to 450mA
Length: 180nm
As both pmos and nmos are either turned on or off, so they are in the triode region instead of in the saturation region, so I suppose the square-law formula as stated below is not applicable in this case. Am I correct?

So if the square-law formula cannot be used, what formula can be used for sizing the transistors in the linear amplifier? Thanks.


texts: How to prevent Quartus RTL Viewer from optimizing my Verilog code?

texts:
module temp (

    input [1:0] A,
    output [1:0] O

);

    wire w0, w1;

    nand (w0, A[0], A[1]);
    nor (w1, A[0], A[1]);
    not (O[0], w0);
    not (O[1], w1);

endmodule

When I do an Analysis&Synthesis to above code, and then go for Tools->Netlist Viewers->RTL Viewer ;

I see the below one,

Now, the thing is, I have to implement a circuit with using NAND, NOR and NOT gates only, and there, I have an OR statement. So, I though I can do an OR out of NOR+NOT. But, as you see, the RTL viewer optimizes(?) my code and replaces NOR+NOT with an OR. Is there a way to prevent it doing so?

Thanks.

edit:


texts:
I am trying to use an AC/DC converter module developed by third party.

In the data sheet, I see following

Is there any way I can do both at the same time?


texts: How to Make two different frequency outptups with Arduino for SMPS inverter?

texts:
i am triying to make a SMPS inverter with Two different chips (TL494), one controlling the low side at 50Khz and one controlling the high side at 50hz. This task is getting difficult because the frequency of one chip affects the other and is not something that results in stable output.
So i want to use Arduino (am new at Arduino), i just want to know if IT IS possible to have One pair of the pwm outputs with 50Khz frequency (one being phase shifted respect to the other to drive a pair of mosfets in totem pole configuration) and another pair outputs running at 50hz (again phase shifted).
Can Arduino do that without problems? The range of frequencys is too different to make that possible? I would like to use an Arduino Nano because it is chepaer.


texts: What is the difference between these 2 types of drivers?

texts:
I have a small doubt about LED Drivers. I have recently studied 2 posts related to LED Drivers - one is LED Driver Circuit and the Other one is Bipolar LED Driver Circuit. Those 2 posts links are also mentioning here for your reference:

LED driver
Bipolar LED driver

It is mentioned that the main advantages of these circuits are for indication purposes, home lighting and decoration purposes. But, is it not possible to use any one of the above circuits to handle all the cases? I mean, is it not possible to use the bipolar LED Driver circuit to operate both bipolar leds and also the normal LEDs by just making small changes in the values or connections?

Can anybody explain in detailed way about the main difference and working of both kinds of drivers?


texts:
Little backstory: I built an electric skateboard about 4 or so years ago and like 6 months back I was riding it at my normal 35 mph and a solder joint came loose on a battery and opened the circuit.  That stopped the board in its tracks. I got a nasty case of road rash and only 1 stich.
Anyway I decided instead of just resoldering that one spot I would pull the batteries apart and use a spot welder this time.
I'm glad I pulled all the tabs off because there was several that were not very secure and would likely cause the same thing to happen again - but most of them were crazy strong connections. There were 3 single batteries that were dead (0.5V.)
I got all the batteries cleaned up and they all have the same voltage, but now I can't remember the safest way to assemble the pack to avoid any sparking or anything.
I have them in a 6s4p and they are secured in those square plastic holders from Amazon and they are assembled 2 cells wide and 12 cells long so the top is in sets of 4: pos, neg, pos, and so on.
Do I just lay the nickel strips down over the top then weld them all up then repeat the same for the bottom, or do I weld all the 4p sets in parallel first then go and connect them in series?
I'm pretty sure the latter is the correct answer but that would involve welding some cells twice and that seems unnecessary. I feel like this is a really stupid question to have, but I'm having a brain fart right now and need some assistance.


texts: PWM low frequency generation low current draw

texts:
I'm a mechanical engineer with the work assignment to develop a low current draw PCB to control a servo mechanism. The device must work on two 9 volt batteries in series (the device must deliver an 18 volt maximum amplitude signal) and remain operable for up to 72 hours of continuous operation, which gives a roughly estimated allowable current draw of (500 mA hrs/72) = 6.94 mA at best.

I'm struggling with the simple feasibility of this project, as 6.94 mA isn't enough to power my Arduino Nano on sleep mode. I can negotiate the operation down to 48 hours of operation, which is 10.4 mA allowable draw (I'm highly aware that 9 Volts do not really have 500 mA of effective power, it's highly dependent on conditions).

Furthermore, the servos I'm trying to control requires both variable duty cycle and variable frequency (based on the brand of servo), and the frequencies vary from 100 Hz to 1500 Hz, which from what I've seen is an extremely slow frequency compared to most PWM applications where desired frequency is in the tens of kHz range or higher.

Can anyone tell me

A) is this possible under any circumstances?
B)is there a better battery out there that doesn't require complex recharging circuits like a Lipo often does?
C) Could I use a LM555 Timer to generate this circuit; a bit of simple calculation shows that the capacitor/resistor combination to be used in astable mode for this chip (according to datasheet) would require a very beefy resistor and capacitor?
D) Is there a low current draw arduino compatible microcontroller that would make this simpler.? I am also somewhat familiar with PIC devices.


texts: Transimpedance amplifier bandwidth limit

texts:
What limits the bandwidth you can achieve on a transimpedance amplifier? Why can you not take measurements at say the GHz range?

I'm guessing it has something to do with an RC element in the circuit.

Thanks!


texts: Multiple 4-wire PT100s with same excitation current?

texts:
Is there any potential loss of accuracy if I use the same excitation current for multiple 4 wire PT100s? Effectively connecting the excitation wires in series.

At present I am using one set of analog inputs (2 out of 4) on an AD7195 to measure voltage over a single PT100. I use AC excitation and feed the current through a precision resistor to act as a reference voltage. I am getting a 200 microKelvin resolution. I need to drive a second PT100 but without duplicating the precision (expensive) excitation components.


texts:
I am still trying to understand what kind of errors are caused in the R2R ladder depending on the amount of resistor mismatch relative to the others.  For example if you have a mismatch of 12% in the MSB of an 8 bit ADC I think you would have a gain error since the total resistance would not be equal to R and and thus the inverting amplifier would not be balanced.  Also I think there would be non-monotonic behavoir and DNL errors.  On the other hand I think that you would have DNL and gain error even with the slightest mismatch(such as 0.2%) in the MSB resistor but you would not have non-monotonic behavior.

On the other hand if you have an error in the lower resistors such as for example LSB(+3) in an 8 bit DAC you would have both DNL and INL errors with the slightest mismatch such as for example (0.2% mismatch) and you would only have non monothonic behavoir if the mismatch is larger than a certain amount (for example 12%).

Can somebody please verify if my assumptions are correct?


texts:
I have this circuit given and we're asked to get the contribution of the 75V source to iR using superposition.
The yellow and red line in the picture are my assumed current flow. However, I couldn't construct a nodal equation that would make sense from it. Are my annotations correct?
Also, I want to simplify the resistances on the left side of 75k ohms and I get 16.7k ohms. Is this correct?


texts:
I´m working on a voltage multiplier with 5 stages. I am using the same value for all capacitors.
I think that my problem is the current load but I actually think that with a resistor in the output of the multiplier but this doesn't work.
I actually calculated the output with the ideal equation (5Vin)-(((n-1)/(cf))*Ioutput).The output multiplier should be 5 times the input voltage.

How I should calculate the value of the load resistor and is the schematic that I made wrong?

Taken of https://www.onsemi.com/pub/Collateral/1N4001-D.PDF


texts:
I am trying to understand the working of a Diode ring circuit from this Video

I find difficulty in understanding how the circuit works.

How is the voltage at the point marked below is equal to ground?

When the RF is 10 MHz and the Local Oscillator is also 10MHz, then only the current flows, right?

Can someone explain that circuit and how that marked terminal is taken as ground reference while he explains that circuit?

And it would be great if someone could help with some frequency examples along with the working of the circuit


texts: using the AD8475 as a single ended output

texts:
simulate this circuit – Schematic created using CircuitLab

I am putting together my schematic and I am trying to figure out if I can use the AD8475 as a single ended output buffer.  AD8475 Found here: http://www.analog.com/en/products/amplifiers/adc-drivers/fully-differential-amplifiers/ad8475.html

My setup has 4 incoming wires (3 signals with a common gnd) going into 3 separate AD8475's.  I then have 4 inputs into my ADC and I would like to have 3 signals all with a common ground again.  This is very similar to the example in the AD7176-2 datasheet but is single ended with 3 buffers rather than differential with two.
ADC7176-2 found here: http://www.analog.com/en/products/analog-to-digital-converters/ad-converters/ad7176-2.html

In the schematic/datasheet it only talks about differential output.  Could I tie all OUT- terminals of the 3 Buffers together and then add a 10ohm resistor before the ADC and capacitors across from all the OUT+'s to the OUT- as in the fully differential mode?

My reason for using the Buffer (AD8475) is I need a VOCM so I can adjust the reference to 2.5V as well as scale down the input precisely.

Any suggestions or help would be great.

UPDATE:
added schematic.
Also the inputs to AD8475 will be scaled down to <5Vpp but it will be offset by the 2.5V reference voltage so it will be from 0V-5V.

looking at the AD8475 there is also some interestingly placed capacitors, and I am guessing those will have to be adjusted as well..

I also found this http://cds.linear.com/docs/en/design-note/dn473f.pdf
which is specifically focused on using TI differential amplifiers as single ended ones.  They seem to indicate all that needs to be done is not connect the out-, which doesn't make sense to me....

Thanks,

scarlson


texts: Xbee Explorer Regulated (WRL-11373) - Current draw

texts: Can anyone tell me roughly how much current the WRL-11373 draws?  I've googled and looked on Sparkfun but can't find any info on it. It says here that the max supply current is 500 mA.


texts:
Hi
I have tried to extract the transfer function of the filter above, as you see it a high order filter.
I have combined the \$C_1\$ in parallel with \$R\$ & \$C_2\$ then make a voltage divider in order to add the inductor.
I always miss the capacitor or I don't get the same result. Where is my mistake?


texts: Name of connector that connects wires to washer drain pump

texts:
I was sent here from https://diy.stackexchange.com/ as they said connector identification is quite common here.

I'm looking to replace a connector that connects to my washers' drain pump.
I first suspected the drain pump to have gone bad, but it looks like the wire itself was burnt or sheared off. I was going to splice the wire back together but figured it would be better to replace the connector all together.

I've attached some pictures to help identify it.

The washer is an Amana NTW4516FW1


texts: Why is that when I use electrolytic capacitors (the cylindrical ones) and measure the end with respect to ground, there is some DC voltage appearing (where in fact it should be 0 volts since capacitor passes only AC signal but blocks DC signal), but when I substituted a non electrolytic capacitor, like tantalum capacitors, they work well. In a simulation program, electrolytic and tantalum shows no difference and they block DC, but in real life, electrolytic fails to function correctly. What's happening?


texts:
I just bought a Bluetooth receiver and whenever I connect it to the radio it started to make some weird noises like beep constantly. I then decided to take a look to this problem on the internet and the solution that I found was to connect it to a 6V supply(https://www.youtube.com/watch?v=_JupcaTRKYk), but if I connect it to 6V it randomly turns off, which didn't happen on the normal connector (5V). What can I do to solve it? I'm new in electronics so maybe you can give me a hand on this.
Here is a diagram of the Bluetooth receiver and some specifications:

And my power supply is a modified cellphone charger which I change the Zener diode for a 6.2V one:
input:100-240Vac; 50/60Hz; 0.35A
|||output: 6.2V---2A


texts: What kind of transistor turns on with 0.2 volts?

texts:
I need a circuit to turn on a LED with 0.2 volts.
I want to do it with a transistor as a switch.
What kind of transistor will turn on at this voltage?


texts: Xilinx Design ISE Tools - See used Block RAMs

texts:
I guess that a pretty easy questions but I really couldn't figure it out. I made a design with the Xilinx ISE Design Tools which uses a lookup table which is saved within the BlockRAM. Where do I see the amount of how many BlockRAMs I used and how many are still free?

I guess it must be somewhere within the Design Summary but I really can't find it.


texts: AC power (220V/50Hz)Track width calculation

texts:
I want to control 5KVA heater through atmega2560 . So, I isolated my heater through MOC3020 optpcoupler and triac(BTA24).
I am confused to design a PCB of power circuitry part. How to calculate the width of the AC supply Track.
enter image description here


texts: VHDL Procedure - Same variable for input/output parameter

texts:
I've written a component where I use the same variable for the input and output parameter of a procedure. A reduced example looks like this:

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

entity var_test is
    port
    (
        iClk        : in  std_logic;
        iReset_n    : in  std_logic
    );
end entity;

architecture behaviour of var_test is
    procedure incr(
        iVar : in  signed(15 downto 0);
        oVar : out signed(15 downto 0)
    ) is
    begin
        oVar := iVar+1;
    end;
begin

process
    variable vVar : signed(15 downto 0) := (others => '0');
begin
    wait until rising_edge(iClk);
    if iReset_n = '0' then
    else
        incr(vVar, vVar);
    end if;
end process;

end behaviour;

When observing vVar in the simulator I expect it to be a counter. This is indeed the behavior I'm seeing when setting the VHDL standard to 2002 in ModelSim 10.5b. However, when selecting VHDL 2008 the variable value is undefined (displayed as 'X') after the first rising edge after reset. Was there a change regarding this behavior between these VHDL standards? Or is this code illegal and just worked by accident?


texts:
I am currently working on high speed ethernet data line, and I wanted to know if there is a way to decrease TVS capacitance.

I thought of putting two TVS diodes in series to reduce capacitance.

What other ways can I reduce capacitance in TVS diode?
Please give an example.


texts: Why Doesn't SPICE Show the Discharging of a Capacitor after Input Voltage is Removed

texts: I have a very simple circuit that includes a capacitor meant to provide a few seconds of battery-like backup to a few LEDs when power is removed.  In real life, it does exactly that. However, when I simulate it in LTSPICE it seems that after the input voltage is removed the capacitor doesn't "pick up" to power the circuit. Being rather new to LTSPICE, is there something about how to simulate it that I'm missing?


texts: lossy open stub of \$ \frac{1}{32} \lambda \$ is equivalent to?

texts:
A lossy open stub having a length of \$ \frac{1}{32} \lambda \$ , is approximately equivalent to :
  a)A small capacitor in shunt with a small resistor
  b)A small capacitor in shunt with a large resistor
  c)A small inductor in shunt with a small resistor
  d)A large inductor in shunt with a large resistor

My Approach:
$$\text{We know for a lossless line : } Z_{in}= Z_0\frac{Z_L + j Z_0 \tan(\beta l)}{Z_0 + j Z_L \tan(\beta l)}$$
$$\text{so, for a lossless open stub having a length of }  \frac{1}{32} \lambda  \text{ , is approximately equivalent to : } $$
$$Z_{in}=Z_0 \frac{1}{j \tan(\frac{\pi}{16})} \text{ , as }Z_L= \infty \text{  & } \beta= \frac{2\pi}{\lambda}$$
As \$ \tan(\frac{\pi}{16}) <1 \$ ,so \$ Z_{in} \$ is equivalent to a small capacitor
so, for a lossy open stub having a length of \$ \frac{1}{32} \lambda \$ , we can conclude it is equivalent to a small capacitor in series with small resistance
so what can I conclude from the options given in this question? please help...


texts:
I'm working on a project and have been stopped in my tracks part way through.

I am designing a system that will power an RC over a distance. So I have a generator, and around 300 meters of cable to a low power system. Since I want to use lighter wires I plan on ramping my voltage very high at the generator, passing it down the wires at a much smaller current, and then finding a way to transform the power down for usability, and then of course return. I dont care about power loss, if the system is only 50% efficient then its still successful.

My issue is that I cant find a way to make the power usable at the low end, without using a classic inductance transformer, which will weigh too much, (i only have about 2 kg to work with). Is there a basic concept that I'm missing for changing voltage at the low end? Also if it matters I need 2kW on my lowside to power my motors...


texts: Help with reverse engineering an LED driving circuit

texts:
I am trying to reverse engineer an LED driving circuit. The schematic I generated from analyzing the board looks as follows:

The main circuit is this one: https://www.monolithicpower.com/pub/media/document/MP3202_r0.91.pdf

From the datasheet I understand that the FB pin is regulated to 104mV. The currently mounted LED needs a max. current of 140mA. However I am not sure if R7 is the only resistor influencing the max. current through the LED? If yes, this would result in 138mA?
The input signal on the left is generated by a Microcontroller and only used for dimming?

Now I need to modify the circuit so the current is max. 60mA only. So is the only modification I have to do to change R7 to 1.75 Ohms?

I am sorry if this seems to be a silly simple question...


texts:
I am an Electrical Engineering student and I'm making a relay test for dad because I want to design stuff.  Basically, there is an oscillator switching the relay constantly, and there is a \$ 1\text{A}_{rms} \$ passing through the 6 switches.  Then I have a circuit which is looking at the voltage across the 6 switch (and if that voltage is too high, that means that the contact resistance of the switches is too high and the relay is buggered).  Anyway, the circuit looking at the voltage consists of two op-amps to make a precision full wave rectifier, and then a single stage passive RC filter on the end to make smooth it.

Now, I wanted to replace the passive RC filter with a Sallen-Key one, so I did the design and found that to get a corner frequency of 10Hz and Q of 0.5, use 1.59Mohm resistors and 0.01uF capacitors (or 159kohm and 0.1uF or 15.9kohm and 1uF etc...).

Then I did the simulation and I'm getting unexpected results.  I'd appreciate if someone could perhaps advise me as to what the problem is or what I've done wrong.

For some reason, if I lower R and increase C, the filter doesn't seem to work properly.

As far as I can tell, both filters should be exactly the same, they have (as far as I know) the same corner frequency and Q factor.

Thanks.


texts:
Im working on a project where I want to measure low magnetic fields in a wire. The range I want to measure is 0.1 - 10 mG or 0.01 - 1 µT in low frequencies (DC - 500Hz) (This range (0.1 - 10 mG) can be larger but I want a accurate measurement in this range).

I looked into hall sensors and current sensors that use the hall effect but these are for larger fields most of the time (and large currents). I thought about using a current clamp and calculating the magnetic field from that, but that relies on the distance from the wire (and with these small field you make it really inaccurate).

At what other things should I look so I can move on in this project?


texts:
I am working on dc ac flyback
We have got 35 Volts for the Panel and the grid 120 volts (RMS) 170 V, 60 HZ
I am trying to choose the right mosfet, I need for M1 S1 S2 ( after the diode D1 and d2).
Idealy I want to control each switch with this driver FOD 8318

It is quite vague (like fog), in the net,  with which parameters I need to choose to select my mosfest.

IN addition I have voltage and current strees
M1 :68 V for 28 A.
S1 and S2 340 v.


texts: how to amplify current coming out of n channel mosfet

texts:
I made a school boy error in buying the BS170. It doesn't produce enough continuous current to power my leds. They're bicolour and can only be wired in parallel hence I would need at least 2 amps!

Since I can't return them I was wondering can I just get some transistors to amplify the current up to 2.5 amps. Also would it have a knock on effect on the resistors am using?

I have 20 copies of this circuit on strip board. Some of the leds are grouped together and switched by one mosfet hence the 2amp

Sorry the led is actually supplied by 5v regulator which isn't on the diagram


texts: Difference between maximum amps for chassis wiring and power transmission

texts:
I am putting together a test system that'll be carrying over 50Amps.

I need to rate the wires that will be powering the device under test and also querying voltages and signals on the device.

Looking at the AWG table hosted by powerstream there are two current guidelines, one gives the maximum amps for power transmission and another gives the maximum power for chassis wiring.  There is a huge difference between the two e.g. for AWG24  3.5A versus 0.577A

I would hazard a guess that chassis wiring is less than 1 metre and power transmission is greater than 100m. Or maybe chassis wiring is something that carries a signal or is only on for a limited amount of time?

What exactly is meant by chassis wiring and power transmission, what is the difference between the chassis and power transmission wiring?


texts: How to plan diagram states of this machine?

texts:
How can I design a tracking system that receives two numbers x and y parallel, bit per cycle, starting LSB, and emitting a "1" when x>2y ?

I know that "2y" is like "y" with zero in right side .. But I still can not plan diagram Conditions.

Note: You need to do it with less than 5 states.


texts: How to get 3.3V output from Vishay 6n137 high speed Opto Coupler?

texts:
I am using 6n137 opto-coupler to drop down 5v pulses to 3.3v level pulses. I found in data sheet the minimum input voltage is 4.5V at Vcc. and the circuit given in the data sheet has pulled up Vo to Vcc using RL resister. Is it ok if i supply Vcc with 5V and pull up Vo to another separate 3.3V level,to get 3.3V pulse output? as shown in below figure.
data sheet 6n137


texts:
I have a problem, found on both ATMEGA1284P and ATMEGA2560.

I have set a 16-bit timer in CTC (tried both Timer1 and Timer5) to give an interrupt every 1ms so I can increment a 32-bit volatile time variable. At the same time, I am sending and receiving data using UART1 and UART2.

This works for some time, however, after exactly 1 min and 6 seconds (~65500 ms ~= 2^16 ms), my UART1 stops working. UART2 and everything else is still working as expected.
When I disable my timer, UART1 keeps working.

I would highly appreciate any help. I have posted my initialization code, let me know if I can provide anything else to find a solution.

UART1 Init code:

#define F_CPU       16000000UL
// (I have also tried disabling the 16 MHz clock and fall back
// to the 8 MHz clock, setting OCR1A to 0x03EF, with no success)

void uart1_init() {
    uint16_t baudrate = UART_BAUD_SELECT(BAUD485, F_CPU));
    UBRR1H = (uint8_t)(baudrate>>8);
    UBRR1L = (uint8_t) baudrate;

    // Clear USART Transmit complete flag, normal USART transmission speed
    UCSR1A = (1 << TXC1) | (0 << U2X1);

    // Enable receiver, transmitter and receive interrupt
    UCSR1B = (1 << RXEN1) | (1 << TXEN1) | (1 << RXCIE1);

    // Asynchronous mode, no parity, 1 stop bit, character size = 8-bit
    UCSR1C = (1 << UCSZ11) | (1 << UCSZ10) | (0 << UCPOL1);
}

// somewhere later: sei();

Timer1 code:

volatile uint32_t time = 0;

void timer_init(void) {
    // This code sets up Timer1 for a 1ms @ 16Mhz Clock (mode 4)
    OCR1A = 0x07CF;
    // Mode 4, CTC on OCR1A
    TCCR1B |= (1 << WGM12);
    // Set interrupt on output compare match
    TIMSK1 |= (1 << OCIE1A);
    // Set prescaler to 8 and start the timer
    TCCR1B |= (1 << CS11) ;
}

ISR(TIMER1_COMPA_vect) {
    // Action to be done every 1 ms
    // Problem also occurs with empty interrupt
    // What I should have here: time++;
}


texts: Do computers speed up at higher temperatures?

texts:
At higher temperatures, will computers get faster? Evidently, one always wants cool a computer down as higher temperatures can damage core components.

However, is it an interplay between silicon, which at higher temperatures will release more electrons and the resistance of the metal components which will increase as temperature does? Or is this negligible in terms of overall computer performance?


texts: Use symetric SMPS power supply for audio amplifier

texts:
I want to know if it's possible to use a SMPS power supply (DC) to power this audio amplifier.
It says I should use an AC 28V/0V/28V power supply but I already have a -28V/0V/+28V DC power supply and watching the amplifier circuit there is a diode rectifier just behind the 28V/0V/28V socket.
Will it works ? Or just burn ? :D


texts: How to import a component in Fusion 360 Electronic Schematic

texts:
Well, I have been following tutorials within AutoCad Fusion 360's schematic editor. So far, I have not found directions for importing single components such as an LTC6993-1. I would typically fetch the symbol, pad, and 3D model from a vendor such as Digikey or Mouser, although all the big vendors have some of the component's information.
Could anyone tell me what the general process would be, or point me to a resource, and I'll do the rest.


texts:
I have been trying to read in values from the ADC of the Psoc 4700s, but I have not been successful with producing results. I am using the 10 bit ADC described in this  datasheet, but I still can't find any tutorials using this ADC.
In my code I start the ADC, Start Conversion, and read, but I am still not getting any values. Here is some code that I am using:

 ADC_Start();
 ADC_StartConvert(0u);
 uint16 val = ADC_ReadResult_mVolts(0u);

However in the debug mode I am receiving optimized_out for the value of val, but other variables have values so I know that the debugger is working.


texts: Power filtering and reference voltages for ADC/DAC

texts:
High precision ADCs need a precision voltage reference.

The question is: If such a reference source can supply the current, can that voltage (after being fed through suitable LRC filters) be used for powering the chip? (Or vice versa - power the chip, then LRC, then reference input)


texts:
For my final project, I am looking about smart grid. What I want to know is that what kind of communication is done in smart grid and the appliances, protocols used etc.

Can I extract a data whether the grid is peak or off-peak?
I have read many papers, but couldn't find an answer for this.

Sorry if this is a wrong forum to post this question


texts: Create a simple oscillator using relays?

texts:
Is it possible to create a very simple oscillator using relays to cause the current to quickly switch back and forth between two lines (or even pulse on one)? It seems like it's almost possible, but I can't figure out a way.
I think if I could design a switch that stops current when current is applied, it would be possible.

I can't figure out how to wire it up exactly. Here's what I'm looking at


texts: What does this ladder logic schematic showing a coil in parallel(?) with a contact mean?

texts:
I am confused on this schematic drawing and understanding what it means when I see the T1 coil in parallel (I'm not even sure) with the PR1 contact?
Does that mean they are logic "OR"ed together or something else entirely?


texts: How to convert spontaneous emission into stimulated?

texts:
I have a semiconductor diode that has spontaneous emission (LED).
The question is what can I change in the fabrication of the diode to improve its performance such that the diode gains a stimulated emission like a laser.
I asked my professor for help and he told me to make the procedure in 4 steps. I do not know if there is a standard way of doing this conversion from spontaneous to stimulated emission.


texts: 8080 assembly comparing which of the numbers is greater etc

texts:
In my 8080 assembly project I need to check if user entered digits and if so do some stuff on it, otherwise display some error and close app.

Normally i would do it like that

CPI '0';if below '0'
JS ERR
CPI 58D;if over '9'
JNS ERR

but there's no JN and JNS in 8080 instructions, So how can I accomplish this?


texts:
This is an AC equivalent circuit of a pre-amplifier. I already derived the formula for input impedance (Zi) but I'm having trouble getting the formula for output impedance (Zo). I can't find a way to incorporate R3 into the formula. Also how do I derive the formula for Vi and Vo?

simulate this circuit – Schematic created using CircuitLab


texts: If I grab any Atmel AVR-based microcontroller off the shelf, will I be able to write code for it using the Arduino SDK?


texts: Protecting battery and USB inputs from each other

texts:
I have this circuit, which I expect will protect my primary cell from USB voltage and my USB port from being powered by the battery.
My logic is;

D2 will stop anything flowing out of the USB port from the rest of the system
When USB 5V is present, the PMOS (Q1) will be turned off regardless of if the battery is in place and restrict flow to the battery terminals.
When the USB 5V is not present the PMOS will be on, allowing current to flow from the battery.
C2 will provide a small amount of charge to handle power loss situations (looking at it now I think I'll increase R3 to restrict discharge back out through the USB port in a power loss scenario).

Is this a sensible circuit?


texts: What happens before the first instruction on a µC?

texts:
I was reading a book by Elecia White (O'reilly) recently and came to a question:

What happens before main()?

Actually as soon as the programcounter is at the first instruction I guess I'm familiar with the process. But what happens between when the voltage first hits the processor?

As far as I know every processor has a RESET line, that is activated until all CLK and PLL stabilize but. My process looks kind of like this:

1) Capacitors gather all the energy they can get

2) The XTALs start working as soon as their supplyvoltage is sufficient

3) After that the PLL starts to stabilize

4) ?

5) Something somewhere recognizes that the circuits are ready and relaese the RESET

6) Profit!!

Which processes did I miss? How does the Something somewhere know when to release the RESET? And how long do these processes usally take?


texts: Connect ground of system A to 1v6 of system B?

texts:
I have an embedded system powered by a 3.7V LiPo battery that will be connected to an iPod's headphone out cable.  The embedded system will perform some DSP on the iPod's audio out signal and use OpAmps to mix it with a second signal.

Through some of my own measurement, I have discovered that the iPod's audio signal is about 2Vpk-pk and is centered around the ground wire provided in the headphones.

I know it is common practice to connect the grounds of the two systems together to make sure all voltages are at the same level between systems.
Instead of connecting headphone ground to embedded system ground, could I connect it to the middle of a voltage divider in my system so that all the signals coming from the iPod are "centered" around (3.7V/2 = 1.85V)?

simulate this circuit – Schematic created using CircuitLab
Thanks,
John


texts:
I was editing a PCB and KiCAD crashed. When I restarted all fields that were previously invisible are now showing, even though their property is set to invisible.

Is this a bug? Or an option I can toggle somewhere. Like "Hide/show all hidden fields."

Opening other older PCBs is the same thing. fields set to invisible still show.


texts: APB PENABLE stays only for one PCLK regardless of PREADY signal

texts:
I followed the AMBA 3 APB specification to design my APB slave. Reading from slave requires several clock cycles to make the data ready for the bus, so I set my   PREADY signal for one clock cycle when the data is valid (PREADY default is always low). However, the APB bus controller does not wait when PREADY goes HI. It keeps PENABLE for one clock cycle and terminates the transection. Any one has an idea what is wrong?

It is running on soft processor CortexM1 on Microsemi FPGA.


texts: Grounding with a battery-powered differential amplifier

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I have made a simple battery powered instrumentation amplifier (based on the AD8429 chip) for some very low noise measurements.
The rough circuit diagram is below.

Note that the BNC input is isolated from the enclosure, while the output BNC has its shield shorted to the enclosure.

I connect to a device under test, which is mains-powered and has some reference to ground, but I wish to make a differential measurement. I look at the output on a mains-powered scope. The cables are RG58 coax, and are no more than metre or two in length.

When I use the amplifier, if I just leave it connected as in the diagram, there is a lot more noise than I would think, mostly at few MHz. But, if I touch the aluminium enclosure with my finger, the noise goes away, and it's closer to what I expected.
This doesn't happen if I touch the bare metal connector of the coax connected to the scope.

Why does this happen? I have a theory, which is that since that the ground reference for the amplifier is coming through the coax shield, and the shield has a reasonably high resistance, current flowing along it gives a lot of voltage drop.

How best to fix this so I can make a low-noise measurement? Should I use a low-resistance connection between the enclosure and the scope?


texts:
I'm attempting to draw the following two circuits up in NI Multisim 10, to attempt simulation and confirm my calculations.

However, I'm not sure how to represent the Vin and Vout sources. Also, multisim only seems to have amplifiers with power supplies, but all theory I read seems to draw the amplifiers without. Does that matter for a eventual simulation?

Also, ff there's any better software for the purpose than Multisim, then please tell.

Thanks.


texts: Reading Current Transformer using Arduino

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I want to be able to read current using an Arduino. I have purchased a Hobut Current Transformer from Farnell (Element14): http://uk.farnell.com/hobut/ctscmicro19-150-5-t/transformer-current-150a-1-5va/dp/2448032?ost=2448032

Here is a link to the datasheet: http://www.farnell.com/datasheets/1850577.pdf

Could someone point me in the right direction to reading current using this current transformer and an Arduino?

Thanks in advance


texts: I am new to soldering, and I am not sure if I did a good job while trying to solder some pins into a HX711. My concern is that the solder in SCK and VCC are touching (also E+ and E-), so I thought this might create some electrical noise, leading to mis-measurements.


texts: Do SMD resistors have to be reflowed black side up, or is black side down okay?

texts: I reflow my own boards in a toaster oven. When I drop my resistors off the paper tape, I always flip them over to black side up before I place them. Should I bother if it doesn't really matter?


texts: What is the technology that transmits voice in 3G networks?

texts:
Sorry for having naive questions and using improper terminologies.
I heard that

2G networks are said to transmit voice only, while 3G both voice and data, and 4G data only.
When the 3G coverage isn't good enough to make calls, a mobile carrier will use 2G instead.

My questions are:

In 3G networks, what technology(s) is (are) used to transmit voice?

is voice transmitted over data, like VoIP? If yes, don't both 3G and 4G transmit data only?
or is voice transmitted in a similar way in 3G networks as in 2G networks?
or can voice be transmitted in either of the above two ways?

If a 3G network contains a data part and a voice part, do data and voice always have the same coverage?
What does "when 3G coverage isn't good, change to use 2G networks for voice service" mean?

when data coverage in a 3G network isn't good, change from using the data part of the 3G network to using the voice part of the 3G network to transmit voice,
or when the 3G network coverage isn't good (for both data and voice), change to use 2G for voice service?

Thanks.


texts: Which is the best memory option to store about 8MB of sensor data?

texts: I'm preparing a data logger with some sensors. I want to store that data to a memory. It should store data for a continues period of 2 days. I need atleast 8MB. Here I'm using STM32L053 for my project. All those non-volatile memories are very small in size. Which way i can make this??. thank you.


texts: construction of voltage transducer to regulate voltage

texts: How do I regulate 80.1 volts dc to 75 volts dc maximum from 600w solar panel Without affecting the output. The maximum voltage required by the inverter is 75 volts and the connection gives me 80.1volts u really need to reduce this. Bear in mind that it's not dc to dc control


texts: Reverse Polarity Protection relay calculation

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i want to make reverse polarity protection without voltage drop ,i was searching and i found this
https://www.edn.com/design/analog/4368527/Simple-reverse-polarity-protection-circuit-has-no-voltage-drop

now , i want to size this relay .
load ( 30 A , 48 V ) 1440 Watt
Does load ( normally closed ) matters with relay?
Where load is normally closed so relay is not operated when power supply is connected correctly.
so if that right then
Does relay ( 12 V , 5 A ) 60 Watt  can do the work ?
if all above right , then the load will taken into concern is when relay energized so the led ( in photo above ) and resistor here will be loads .
Thanks you .