texts:
I have created the low cost oscilloscope and need to estimate the analog bandwidth.

I do not have any specialized equipment and just trying to estimate it by watching the response to the square signal.

Here is the 0.5MHz square wave signal:

I think I can estimate is as 6-8MHz. Am I right?


texts:
I am doing a project in which I have to serially communicate data from 8051 Micro-controller to PC.

The problem is that when I transmit the data from 8051 and receive it over the Putty  terminal it gives me garbage data. I get the same garbage results when I simulate it on the Proteus. I have also set the same baud rates for the micro-controller and the terminal.

Can someone tell me what possibly the problem could be ?


texts: LED upgrade for cooker hood (12 V AC to 240 V AC or 12 V DC)

texts:
I've got a cooker hood with some problematic 2x 12 V 20 W G4 bulb downlights. I want to replace them with LEDs. Unfortunately the units are physically too small to accommodate suitable LED G4s.
Therefore, I'm considering replacing the whole downlight units with LED ones.

The problem I have is any downlight units I find are either 240v AC (I'm in UK) or 12V DC, requiring a driver. However, the supply to the bulbs is currently 12V AC, rather than DC.

I looked to see if I could just use 240V units, but unfortunately the switch is a soft switch, which operates a PCB-mounted relay-switched 240v to 12v transformer which looks a bit awkward to remove from the board.

What would be a sensible option? Thoughts I've had are:

12V AC -> DC rectifier, although not entirely sure whether heat dissipation would become an issue (2x LED units draw about 6W)
Use 12 V AC with AC relay to switch a new parallel 240 V feed to the new units. Possible problem with this is that I imagine it'll reduce efficiency and defeat the purpose of doing this and also the transformer buzzes with no load so if there's only a relay as the load it might still buzz. Plus the AC relays seem expensive...
bite the bullet and desolder the current AC transformer and try and use the existing relay output to switch a new standard 12 V DC LED driver (only reluctant to do this because I'm a (lapsed!) physicist rather than an electronics person and a bit nervous I'll trash an otherwise sound PCB!

Thanks for any pointers.


texts: Separate ground for gate opener control box?

texts:
Is it worth electrically isolating the control box of a gate opener from a well grounded steel fence? Or does the grounding of the fence have the same effect?

My house is in a very lightning prone spot and has been struck with much damage twice in 10 years. The lot is surrounded by 2000' of steel wire fence attached to 1' deep steel t-posts every 12' and 2 3' deep 2.5" steel posts every 200'.

I'm installing a gate opener and am afraid it won't last long in these conditions. I can isolate the control box and everything connected to it except the wires from the gate lock and the actuator, which are bolted or welded to the steel gate and fence. I can run those wires through heavy duty surge protectors, which aren't cheap. Then I can ground the control box to a ground rod separate from the fence.

The gate opener is powered by a 12 volt battery in the control box, charged by a solar panel.

But is it worth going to this expense when the fence itself is grounded by the fence posts? Or since the fence is grounded can I just attach the control box directly to the steel posts with no difference? Is it worth doing something in between, or does only the weakest link matter?


texts: Under which value it is not recommendend to discharge a Li-Ion battery? How fully discharging battery affects a battery life? What happens if we leave a battery on charger, even battery is fully charged?


texts:
I was reading about the selection of output capacitors at the output of buck converters and found this Link

The accepted answer states that before I select an output capacitor, we must fix the desired ripple current and then choose the inductor based on the ripple current.

How to choose and fix the ripple current? Should we just assume the ripple current to be 20 to 40% of Iout max current as mentioned in the TI App Note and proceed with those calculation steps.

I am not sure I get this. I always thought that the selection of output capacitor was based on ripple voltage.

For example, If I have an IC Whose Vcc ranges from 0.8V to 1.2V and typical Vcc is 1V. My Buck will produce 1V with a ripple that must not exceed the Min and Max Vcc of the IC. So, my ripple should be less than 200mV. So, here, obviously our ripple voltage is very important. If the ripple voltage is very high, then our 1V IC may get damaged. But we also calculate ripple current.

How is the ripple current more important that the ripple voltage. What happens if we have high ripple current and low ripple current?

So, I think we would select a capacitor based on our calculated ripple voltage (To be less than 200mV).

So, is our estimate of Inductor ripple current same as the output capacitor ripple current ?

I tried other app notes also. But I couldn't find a formula that mentions the calculation of output capacitor ripple current.
And can someone tell me how output ripple voltage and output capacitor ripple current are related and which is calculated first and based on what parameter.


texts:
This question stems from my own curiosity, so forgive any vagueness.

Imagine the following scenario:

We have a MCU which outputs a PWM signal to control a motor's speed and direction. We ultimately want to drive a 5hp motor using a VFD.

What would we normally need to supply to the VFD to drive the motor? How would it know which direction the motor needs to travel in? Does a PWM signal alone provide this information?


texts: How to acquire current values in data acquisiton accurately when using a shunt resistor in a current loop?

texts:
Here is the setup I use.

Since the DAQ system is only able to read voltages first I record the voltages by a shunt resistor. But I need the "current values" at the end. Transducer will make the current vary between 4 to 20 mA.

If the resistance is constant with respect to current one could just divide the voltage readings to resistance and obtain the current in the loop.

But I observed that the resistance is not the same for different currents. For example for a constant applied 20mA current the resistance is 248.74ohm and for 4 mA 248.27ohm. Is it better in that case to obtain a calibration expression (current to voltage) and calculate the currents in that way instead of taking the resistance a constant?


texts: Is it possible to damage phone battery when charging with a current source?

texts:
Is it possible to damage a phone battery when charging with a current source?

Situation: I am currently busy with a project where we want to use 200 watt solar panel to charge as many phones as possible.
My plan is to find a charge controller to convert the voltage to 5 volt. After which I can connect about 10 USB sockets in parallel.
A battery will also be connected to the charge controller to reduce the intermittent behavior of the source.

Because the current generated by the PV module can be quite high. I was wondering if this could damage the phone batteries.

Thanks


texts: Correct Way to connect 5 car batteries in parallel

texts:
My RV (which I bought used) came with 3 Deep Cycle Marine batteries in Parallel. A previous owner added wiring inside the coach for 2 more batteries, but they were not there when I purchased the coach.
The 3 batteries needed replacing, so I purchased 5 27DC batteries. The wiring is shown in the below figure. When I connected these, I got some burned wires. I've replaced them with 3/0 wire on the 3 batteries.

The 3 batteries in the upper left are in a compartment in the chassis of the RV. The other 2 are inside the rig in a closet (where a washer/dryer used to be.

Is there a "best practice" to connect all of these in parallel?

I have looked in to a disconnect switch for the battery bank. They appear to be connected to the Negative. Why the negative terminal?


texts: How to use 7 segment display to count levels on proteus

texts: Can someone help me figure out how to add a 7 segment display to my circuit. For instance, if the input is 000 the counter displays 0 and no led lights up. If the input is 001, then the display shows 1 and D3 lights up etc. I would really appreciate some guidance here. Thanks!


texts: 8 bit PICs: timer1 asynchronous vs synchronous operation

texts:
The 8-bit PIC family (I'm working with pic18f46k22) offers some timers (timers1/3/5) that can work in both asynchronous and synchronous modes when clocked from an external source.

The obvious differences are:

asynchronous operation gives the possibility for timer to run in sleep mode
An asynchronous source can clock the timer faster since it is independent on the system clock (table 27-12):

and as for the advantages for synchronizing the external clock source... well, I can't see any. One disadvantage to think of is the possible corruption of data if the CPU tries to read the counter while it is incrementing, but the datasheet states:

  12.5.1 READING AND WRITING TIMER1/3/5 IN ASYNCHRONOUS COUNTER MODE:
  Reading TMRxH or TMRxL while the timer is running from an external asynchronous clock will ensure a valid read (taken care of in hardware).

Can someone please explain why did they add the possibility to synchronize the external clock source with the internal phase clocks? I feel that I'm missing something.
Thanx a lot


texts:
I have the following problem. I have to fill in the blank spots in the picture below.

I'm not sure how to answer this question.

My book just says:

If \$V_+ > V_-\$ then \$ V_{out}=max\$

If \$V_- < V_-\$ then \$V_{out}=min\$

Is there an equation of sorts that will help me solve this problem?


texts: I download symbols and footprints from the component supplier into a project's library to go faster but I realized that many of the standard components footprints are slightly different in KiCad, like for example the SOT-23-6 so my question is: is it better to stick to KiCad footprints or just use the suppliers footprints?


texts: Driving multiwinding current transformer

texts:
About the circuit below:

I'm using a Current Transformer with two identical secondary windings, L1 and L2. I can use them indistinctively since they are 1:1. The relationship with the primary is 1000:1, that means 1A in the primary is 1 mA in the secondary.
I'm using L1 as main secondary. I'm using L2 to inject a current for testing. Whatever current I put in L2, it appears in L1. Whenever I decide to inject current to L2 (preferably when there's no primary current) I activate a PWM from the micro and make it pass through high pass filter to inject only AC current to L2.
When I pass a current through primary, I get the expected voltage across the burden resistor R18. See waveform 1. That waveform corresponds to the max current I will measure. I have left L2 without burden resistor, because otherwise it would load L1.
As L1 & L2 are 1:1 I should see the same voltage across L2. But here is the point, I see a much higher voltage. See waveform 2. Why is this?

So, somehow I need to provide some kind of isolation between L2 and the microcontroller to protect it against this high AC voltage. Also, L2 needs to be unloaded so it does not affect signal in L1. Any suggestion on this? I tried to add an analog switch like this one between the cap and L2, but this switch has some internal diodes that clips the signal seen in L2 then it clips it in L1.

Waveform 1

Waveform 2


texts:
I am designing a circuit to amplify audio from microphone as well as removing dc offset from biasing the microphone. I searched for circuits available online for my personal project. I came across circuit from Sparkfun. I understood everything except the capacitor and resistor connected to non-inverting terminal of op-amp. Please explain the use of the capacitor C2 in the above schematic and why it is connected with the resistors R2 and R3.

Also, I am going to convert the analog signal after amplification to digital form using ADC. I want suggestion on bit resolution for audio applications that will provide acceptable voice quality during recreation of the voice.

Here is the schematic from the Sparkfun web site shared under the Creative Commons license.


texts: DC motor rpm change by under supplying voltage

texts: If I have a 6V dc motor running at 20 RPM with a gearbox already attached and I only supply the motor with 5V from a cellphone charger what will my new rpm be?


texts: Do I need a Gate driver on a Power Mosfet if its working without it?

texts:
Do I really need a gate driver?
Here is what I have going on.

12Volt 100 watt incandescent bulb drawing 8.33 watts   (Taxi light on a Cessna 172)
The switch that turns it on and off reportedly wears out from current draw and needs frequent replacement (suggested every three years).
Instead of that I thought a Mosfet would allow the switch a long happy life...
I’m using a IRF3205 HEXFET® N Channel Power MOSFET WITHOUT a gate driver.
12Volts is below the 20v max on the gate and works fine to turn it on.
Of course it just stays on if I take the gate voltage away so....
I have inserted a 270K ohm resistor across the gate to the source as a drop down resistor.
leave 12 Volts applied to the gate and it stays on and when I remove the 12 volts from the gate it shuts off.
Is this the WRONG way to operate this (although it works just fine) I’m not sure if It is okay to leave the 12 volts on the gate?


texts: How to calibrate Accelerometer sensor physically?

texts:
I am having a development kit DK20948 that is a 9 axis IMU sensor on it.

and to use it I am using SmartMotion eMD Page number 47, when using the CLI tool, I am getting data of the sensors and an accuracy flag, where accuracy is rated between 0-3, 0 is lowest.

I have tried to test the accuracy flag with Magnetometer by calibrating is by moving the development kit in an '8' motion. Before calibrating, my data was kinda gibberish but after calibrating, I am getting the reading in 2% compared to my phone's sensor and the accuracy flag goes from 0 to 3. So I believe accuracy flag represents kind of calibration.

I want to calibrate the same for accelerometer. I know software technique of putting it on a levelled surface and averaging it. But is there any phyical method in which I can calibrate it? I couldn't find anything reliable on google except someone's thesis where they put it on a linear actuator and fire it. I highly doubt the approach because not everyone has linear actuator lying around.


texts: How can you add custom supply symbols in Eagle?

texts:
I have multiple 3.3V 5V, 5.2V, 4.8V, and 13V supplies. I tried copying a device from the supply library to mine and renaming the symbol and device, but when connecting it still refers to it as the original voltage supply device net.

Whats the proper/easy way to create a new, custom, and perhaps duplicate voltage supply?


texts: How does this voltage adjustment circuit work?

texts:
This is a real-world application. My circuit 101 knowledge is not up to the task.
I cannot understand the purpose of the portion of the circuit highlighted in yellow. With the presence of diode D3 and D4, I can't see that R_10K ever gets utilized. The only scenario R_10K will have some current passing through it is when V@pointA < 0.7Vdc and V@pointB > -0.7Vdc, but that's an impossibility, you can't reconcile the currents flowing in R14 and R15. The circuit just seems impossible to operate. I must be missing something here.

In retrospect, judging from all the answers to this question, the place I was stuck upon was the notion that: Once D3 and D4 are conducting, they will short circuit R_10K.

In a real-world situation, a forward-biased diode is not a short circuit.


texts:
What is the best (i.e. most energy efficient (has the least energy loss)) way to reduce 120 VAC to various DC charging levels for simultaneously smart charging:  a 12V deep-cycle/starting battery, an 18V tool battery, 7 3.7V Li-ion cells, & up to 8 AA/AAA nimh cells that all charge independently of each other?

Note:  I'd prefer to have/make one bench charging station that allows me to simply connect one or more batteries/cells to it, rather than having a power strip & a mess of AC adapters/converters.


texts: How to interface with SMD pads to a custom MCU on PCB

texts:
I have a board that I want to remove the existing microcontroller and apply my own. I'll be swapping out one brand of microcontroller and putting in something completely different and so I intend to make a small PCB with the required micro and interface, but I need a way of breaking out the old microcontroller pins to the new board.

Basically, I want the reverse of this:

https://www.raypcb.com/things-to-make-sure-for-having-awesome-qfn-pcb-pad-design/

Here you would mount a SMD component and break out the pins you want, but now imagine you have the SMD pads available to you and you need to interface them elsewhere.

We are talking about 56 pins in a 8mm x 8mm square arrangement, 14 pins each side:

My main intention is to NOT desolder the rest of the board (~50 mechanical keys), instead remove this and interface with what is already there and keep the rigidity of the original board.

Desoldering the keys I am concerned I will damage some. If it wasn't for this fact I would just design my entire board, and transpose the pieces from one to the other, however, I am not confident of not being able to remove all components safely.


texts:
I have two terminals which I will measure resistivity between. I will be manually touching the terminal pair to different value resistors.

The terminal pair might look something like a 9v battery plug:

I don't want to be precise about where I touch the resistor (lining up the terminals with the resistor wires).

Is there some kind of "pad resistor" (the size of a small coin) in which I can just touch two terminals anywhere on the surface and have the same effect as if i were using set resistors?

Note: the reason I am using resistors is so I can have a series of pads with unique signature based on resistance over the terminals. If there is some other solution in which I can have unique "pads" be recognised by a microcontroller as different without using resistors, this will work also.

Thanks!


texts: Determine the output capacitor parameters of flyback SMPS design

texts:
I am designing a SMPS using FPS from Fairchild. But I am having a bit of doubt on how to get the output capacitance for my output. I am thinking that the method to obtain the capacitance will be the same for all SMPS designs. The only parameter I have is the ripple current Icap, but how to go about the other paramters is a bit of doubts.

I have attached a jpg off a cut of the explanation from this application note -
 Application Note AN4137, "Design Guidelines for Off-line Flyback Converters Using Fairchild Power Switch (FPS)" 2003.
 Maybe I get some help on this.

From Diagram:

Parameters already derived are Icap(n), Io(n),Dmax,Fs,IdsPeak,Vro,Kl(n),Vo, and Vf.

Parameters i want to get is C(o),Rc(n).

Thanks.


texts: Keeping power on a capacitor after its charged?

texts:
I am building a capacitor bank. I have them soldered in already. My question is simple-ish:

Can I keep the power on while one capacitor is done charging? Like If i hold the charge button on for 10 seconds will it hurt the capacitor. Even if It is a slow possess but in the long run yes, I need to know.


texts:
After studying Multilayer Ceramic Capacitors (MLCCs), I have come to grips with the chemical phenomenon that decreases the effective capacitance of a given part.
Without getting into too much of the chemistry, higher voltage reduces the dielectric strength of such capacitors significantly, reducing the capacitance. This is called the DC bias because it is caused by a constant voltage offset applied across the capacitor.
However, I am planning to use some MLCCs as isolation capacitors, which will pass AC signals of a small amplitude regardless of the DC bias across them.
The capacitors are rated for 1 kV so they should provide reasonable isolation before breaking down. I am imagining that when isolating signals that have a greater DC offset, the dielectric will be further broken down and thus even the AC signals will not pass through with the same source/sink capability on the other end due to less capacitance.
If this is not the case, it gives me much greater design freedom. If it is, I would like some proof that accounts for both the AC signal and the DC bias.
Does the DC bias of a MLCC affect AC signals?


texts:
I have a small 1.5A @ 12V (~10 Amp stall current @ 12Vdc) DC Brushed motor connected to a H-Bridge switched with 20KHz PWM.

The motor is connected to the bridge through a 3 meters long cable:
[H BRIDGE]--PCB-TRACK--[CONNECTOR]=====(3 METERS CABLE)====[DC-MOTOR]

My concern is that the cable will emit EMI.
At 20KHz switching 1.5A through 3mts long cable, is this a valid concern?

Should I use some inductor between the bridge and the connector to the cable to damp high frequency? Or LC low pass filter?

I don't know how to calculate the loss insertion needed for the filter.
Ideally I want the loss to be infinite above the cutoff frequency, but considering the practical implementation, should I just go with as more loss abbove 20Khz, as better it is?


texts: Frome tabletop prototype to a usable home device

texts:
I see a lot of questions dealing with going from prototype to production but I've got a more modest problem. I am building a couple of home automation devices for myself. I am able to build a table-top Arduino-based prototype using breadboard but I cannot find a good resource that would help me taking it from "table-top" to "usable" even if it means usable by myself. To give you an idea what I mean, here are the typical issues I am facing:

"Right" way to connect things without breadboard. Arduino board has special headers for it, so what kind of plug does one use to outfit wires with in order to connect into them (short of sacrificing the test wires I have)? Should I just solder things together or should I use a small PCB (we are talking about a couple sensors and one or two resistors)
"Right" way to outfit a long wire between Arduino and a sensor. Ideally, I would like to have a small 3-wire jack with female side connected to Arduino using short wires and male side at one end of a long cable which will have a sensor on the other end. Of course I can just solder things together but I wonder if there is a better way to do it.

And things like this - basically going from table-top design to a neat box one can use at home without naked wires sticking outside and ugly mess of stuff soldered together inside. :-)

Any tips would be highly appreciated.


texts:
First of all thanks for reading this post. I am designing an isolated board for several peripherals for which I need your help/suggestions. The board contains a buck converter (like LM2596) to step the input voltage from (9-36V) to 5 V. Then there is an isolation converter ( Vin=5V, Vo=5V isolated). My first questions is regarding this isolation converter. The only component I could find online is 0505 series (0505 converter) which is limited to 1 W only. I need at least 1.2 Amps of current supply. The peripherals include one isolated RS485 transceiver, one CAN bus transceiver and two or three ADC connected via I2C bus with a digital isolator between ADC and microcontroller. Following are my questions regarding this board and I would really appreciate your help.
Is there any similar model like 0505 converter(isolated) with higher power handling capacity?
Is the board design ok? with respect to isolation!
The microcontroller runs on 3.3 V so I would need to use a 5 to 3.3 V linear regulator, would that effect the performance too much? is so should i go for 5 to 3.3 V isolated converter?
Any other suggestions regarding this design?
Here is the picture of this board.


texts: Is there a way to make an experimental magnetic head?

texts:
I recently had a magnetic stripe on my bank card fail and I was curious to find out the exact nature of the corruption which would require scanning the surface of the stripe and determining its magnetic characteristics.

I was wondering if there is any simple setup that would allow me to just use a probe and make a map of the magnetism of the strip? Note that I do have a cast iron X-Y table which has dials calibrated in thousandths of an inch. So, it is easy for me to locate the probe to that degree of precision.

I assume that there is way to do it, because I know in the old days there were these things called hard drive "microscopes" that had some kind of needle and you could literally read the bits off the disk platter, bit by bit, with the microscope. But, what I don't know is how easy it is to make the "needle" part of such an apparatus. Is this really simple, or would it be a complicated project?


texts:
Edited:

I'm having a trouble to estimate Vpp of a RCL oscillation circuit. I found a peak to peak inductor voltage (Vpp_L) varies with the different combination of LC, which makes sense because the frequency (f) is different.

Then what is the relationship between Vpp_L and LC combination?

Below graph is to see the oscillation voltage of LC configuration.
Vin = 10v
Trise = 0.1ms
f = 11kHz.

Simulation:

Vpp_L = Vout = 2V @ first wave.


texts: What is the appropriate name for camera modules/sensors? And what kind of supporting circuirty is needed?

texts:
I have seen CMOS Imaging Sensors (OmniVision, Aptina, ST, etc) as well as Camera modules (like the ones in smartphones; e-con, OmniVision, etc), and I know there are the finished product cameras (Cannon, Nikon, Sony, etc). Now, I understand that sensor is only the imaging chip itself, and module is the chip on something that connects to something else. But, is there an common industry name for the different finished products (modules) that can be used in a DIY project? (maybe differentnames for differnet connection methods? with or without lenses?) (as far as finding it quickly on DigiKey, Mouser, Google, etc)?

Now, following this, for a DIY project - it would be really hard to use an imaging sensor due to its small footprint. So, if I am to get one of those small cmos modules, is there any need for supporting circuitry? Or it can be directly connected to a microprocessor to get an image/video?

Please bare with this question, I understand it is very basic to some of you, but it is not as clear to some.


texts: Troubleshooting a SEPIC regulator (MIC2296)

texts:
I am trying to regulate a 5V input, which drops to around 3.5V when a large load is applied. I need to keep the 5V steady, and I am willing to do this at the expense of current, which is why I thought that using a boost regulator is appropriate here.

Since my input voltage can be slightly above 5V when the load is small, and under 5V when the load is large, I think I need to use a SEPIC regulator. The datasheet for MIC2296 says that it can be used in this way, although it does not provide a sample schematic.

Here's what I have so far:

There are two problems with it.

It is unstable. A correct voltage is provided for the first minute or so (although it oscillates by ~200mV even during this period). The voltage at "FB" pin hovers around 1.2V (shouldn't it be @Vref, which is 1.24V?). After a minute the output voltage suddenly spikes and goes up to ~9V. Voltage at "FB" drops to ~0.9V. At this point I have to disconnect power, since my load resistor can't handle too much current.
If I power on my actual circuit with this regulator and then activate the current hungry load, the regulator fails to keep the voltage at 5V and allows it to drop to < 4V, so the regulator is not doing its job of trading current for voltage. Why?

The load in the circuit will switch between a light load (~50mA) and a heavy load. The heavy load will be anywhere between 500mA and 800mA, depending on what my battery pack can provide at 5V.

What can I do troubleshoot these problems?


texts: Bridge rectifier still putting out ac and dc, why?

texts: I have a bridge rectifier on my snow blower and it still producing 8 V of AC current and 24 V of DC current. Anyone know why it would still be producing both AC and DC?


texts: Addition of step disturbance to a microgrid state space model

texts:
If we are having a microgrid model in the state space form as \$\dot{x} = Ax\$ where \$A\$ is complete system matrix.The matrix \$A\$ includes all the active power , reactive power, load currents, line currents etc as states. Now i have to add a disturbance in the form of an additional active load. how can i add it in the state space model.

The reference paper is given in the below link (Pg 622).I am facing problem in getting simulation results. How to obtain the responses
https://ieeexplore.ieee.org/document/4118327/?reload=true


texts:
Suppose only one multiplexer and one inverter are allowed to be used to implement any Boolean function of n variables. What is the minimum size of the multiplexer needed?

answer is- 2^(n−1) to 1

=======================================================

Any help provided to understand this question is appreciated.


texts: Lock-in amplifier output to spectrum analyzer

texts:
In several lock-in amp tutorials and experiments (including at the end of “Physics 111: Low Light Signal Measurements” on Youtube), the lock-in amp X or Y output is applied directly to a spectrum analyzer. I have two very basic questions about this:

After the lock-in amp mixer section the signal is rectified – how can the spectrum analyzer display be accurate with such a rectified signal?
The rectified signal is low-pass filtered before the lock-in amp output – so the spectrum analyzer is only seeing whatever high frequencies that are able to pass through the filter, correct?


texts:
I am making a circuit with a microcontroller that has a periodic need to save about 500 bytes of information in a non-volatile storage. Running only on a supercap that might be charged up rarely, the microcontroller wakes up periodically,
takes some readings and then writes those items to either an off-chip EEPROM via SPI communication, or to a block of its own flash memory.

I stumbled across this type of chip from Cypress - http://www.cypress.com/products/f-ram-nonvolatile-ferroelectric-ram

The F-Ram chips also use SPI as well, but most of the advantages over EEPROM or Flash writes, like faster write speed, no special voltage or current requirements, 100 trillion cycle endurance, and many others
made me wonder if it was too good to be true. I read the data sheet and it shows that the cells are destroyed by a read but the chip takes care of writing the value back to the cell on reads.

Other than the need for an external chip (vs on-chip Flash in the micro-controller) I could find nearly no drawbacks to using F-ram type devices for what I want to do. Does anyone else know of any disadvantages to using F-ram over EEPROM or Flash?


texts:
I'm using Altium 17. Recently I just imported an Eagle project then I generated the component library with Design-> make integrated library. The components and their footprints created successfully and I added them to my project. After I completed the schematic, I generated the PCB but I got into a very strange problem, when I move these imported components the route hint appears and when I place the component all route pins to that component disappear. This problem happened only for imported components from Eagle project. When I close my project and reopen it all the pin names from component disappear and when I move them the hint no longer exist at all. I checked the schematic and PCB library and couldn't found any problem. I tried to create a new schematic symbol and copied the pcb, but didn't work.
Here are some pictures.


texts: SEPIC converter working in BURST mode without having one

texts:
I designed a SEPIC using the LT3467 with coupled inductors. It supply 17V starting from a 12V input.
On the simulator (LTSPICE) everything works, but on the test board there is a problem.
With 70mA output current there is a ripple of 1V (see pic attached) caused by the wrong regulation of the chip.

It seems that the regulator is working on burst mode, and that is the the cause of all my problems.
Here it is a pic of the switching node.

Do you have any idea on how can i make the switching node switch regularly?
Maybe there is  a problem on the feedback loop.
I cannot post the pic of the schematic because i don't have enough reputation points, so if you need it you can tell me another way to post it.

Here is the schematic:

In the  link below you can find the schematic and the output node and the switching node with 200mA at the output.


texts: Trying to determine the internal construction of a BLDC Motor

texts:
The motor is an Electrocraft RPX52600V12. The datasheet indicates 14 poles, 12V, 20.5A, .6 Nm, 1 Ohm, and .6mH.  It is 'Y' connected. There is no access to the common center connection. I don't know if it has concentrated or distributed windings. Measuring phase to phase when turned with a drill it produces an absolutely perfect sinusoidal waveform on an oscilloscope.
Q1: Does this mean it is constructed as if it were a PMSM with sinusoidal BEMF rather than a BLDC Motor with trapezoidal BEMF?
After reading the stack exchange topic under 1 I am still uncertain about the answer to the above question because
Rotating the shaft it cogs 24 times. One post I found here said:

"The # of cogs per revolution is equal to the least common multiple of
the number of poles and the number of stator slots"

The least common denominator for 14 poles and 24 cogs is 1, an impractical number of slots.
Q2: Is it possible to know the number of stator slots?
-K


texts: Any way to surface mounting a through-hole resistor?

texts:
I need to solder a 2W through-hole Resistor on one side of pcb, mean like smd component but this is for through-hole resistor. I google and found there is a way call ZI-form, image is below. So is this possible? Any problem with this solution? Is there any way else better?

Thanks very much


texts: AXI Stream Master - M_AXIS_TVALID not always be '1' during a transaction and M_AXIS_TLAST

texts:
I am implementing my AXI Stream Master module which can be use with Vivado DMA module. The connection of module is shown:

I have 3 questions:
1.) Could the "m_axis_tvalid" signal be non continuous at '1' during the stream transaction? Because some calculation delay might occur in the "axis_top_test_0" module, so the the m_axis_tdata might not be provided continuously. The provided reference only gives some simple condition. I have written my testbench signal which is shown below, so that you can understand my question in a better way:

2.) Is it necessary to set the "m_axis_tlast" to '1' when my transaction is finished? I test the xilinx sdk provided program xaxidma_example_simple_poll.c and it always stops at this line272:
while ((XAxiDma_Busy(&AxiDma,XAXIDMA_DEVICE_TO_DMA)) ||
    (XAxiDma_Busy(&AxiDma,XAXIDMA_DMA_TO_DEVICE))) {
        /* Wait */
}

Then, the program cannot be ended. When I rerun the program again, I can see that the data is transferred to the Rx already (which is the result of the 1st run of the program). Does it mean that the AxiDma is always busy when custom module asserts m_axis_tvalid to '1', if the dma does not receive m_axis_tlast = '1', then the dma will always be busy?
3.) Let's come back to the 1st question, I tested the implementation in question 1, and I still get the result of question 2. So, the only way to resolve it is to first store all my calculation results in a buffer, then I trigger the m_axis transaction once?


texts: Convert RF to DC, specific frequency with extremely low current circuit

texts:
I want to build kind of keyless entry for my car.

My car will have a radar sensor and whenever some body approach it, it will trigger a transmitter (unknown)

Then, this signal will wake up a microcontroller(Arduino) on my keychain and it will trigger a classic 433mhz module to send a specific message to the car that will open the car.

The problem here is nothing BUT the transmitter and the receiver while the transmitter can have at much as 10-20mA, because it will only works whenever the radar detect someone close to the car, the receiver(unknown) on the other side must be extremely low current because it will ALWAYS listen and will be powered by a much much smaller battery (compared to the car)

I'm a beginner, i don't know much about electronics. This means i don't know if somethings like this exists..


texts: Could one actually build electronics without EE degree?

texts:
I understand that a teach yourself electronics book can "teach you electronics", but just how far can that take you developmentally?

I want to have the ability to solve a problem requiring the development of a specific electric motor for example, of certain HP rating and speed as well as knowing the calculations and thicknesses required. I have spent a long time teaching myself the branches of math, and have come to enjoy it too, but I do not want to spend years learning all of the math when only some of it is required.

Can I "thoroughly" build electronics with a teach yourself book? My predicament is that I support a household with a full time manufacturing job that pays well, but gives me no room for full time at a university. I understand that online classes can only go so far as well. My apologies if the above makes no sense in any way.


texts: ADC problem with ATMEGA32 using external clock more than 8MHz

texts:
My code is supposed to check a 50Hz signal with AVR ATMEGA32's ADC. It works at 6MHz with an external clock in both real and simulator. But when I use a 12MHz external clock the ADC doesn't work well at all in real and it almost missed the AC signals.

When I use the simulator, it's perfect but in real it's not.. I have set the fuse bit and I turn the ADC on and off before any reading.

Any idea? thx


texts: ATtiny85 simulation in AtmelStudio 6.1 (build 2730, SP2)

texts:
I have written a piece of code which manipulates the DDR for port B:

#include <avr/io.h>

int main(void)
{
    DDRB = 0;

    DDRB = 1;
    DDRB = 2;
    DDRB = 4;
    DDRB = 8;
    DDRB = 16;
    DDRB = 32;
    DDRB = 64;
    DDRB = 128;

    return 0;
}

I'm using the simulator and I'm having a hard time in figuring out how this maps in the I/O view, and what will happen on the actual device. I'm stepping over the DDRB=1..128 instructions.

As expected, DDRB values in the I/O view go from 0x1 to 0x20 as I execute the first 6 instructions, DDRB=1..32. However the other two instructions DDRB=64,128 have the effect of setting DDRB in the I/O view to 0x0. In a way this is not entirely surprising, as the ATtiny85 has only 6 PB pins. But is this behavior expected?

The real question is: what are the little squares in the I/O view next to the value of DDRB saying? Here is the state of DDRB in I/O view after each single instruction in main:

DDRB=  0;  --> DDRB    0x37    0x0    000000
DDRB=  1;  --> DDRB    0x37    0x1    000000
DDRB=  2;  --> DDRB    0x37    0x2    000000
DDRB=  4;  --> DDRB    0x37    0x4    000001
DDRB=  8;  --> DDRB    0x37    0x8    000010
DDRB= 16;  --> DDRB    0x37    0x10   000100
DDRB= 32;  --> DDRB    0x37    0x20   001000
DDRB= 64;  --> DDRB    0x37    0x0    000000
DDRB=128;  --> DDRB    0x37    0x0    000000

Also, if I hover the mouse on the little squares, their names range from Bit 2 (the rightmost) to Bit 7 (the leftmost). How does this map to the pins of the real device? and also Why are they named from 2 to 7 instead than from 0 to 5, as on the device (PB0-PB5)?.

I thought initially that the configuration fuses in the simulator are responsible for certain bits of DDRB not being programmable. For instance I know that RSTDISBL must be unprogrammed to enable PB5, and I guess the same is true for the corresponding DDR. But which column is PB5 on the I/O view?.

I also tried to set the fuses in C code:

FUSES =
{
    .low = 0x62,
    .high = 0x5f,
    .extended = 0xff
};

The setting 0x5f for the high fuse should mean that RSTDISBL is disabled, according to the online fuse calculator. However the behavior in I/O view is still the same.


texts: Changing the orientation of the capactior in a simple integrating op amp

texts:
How does the terminal relationship i=c(dv/dt) change if you switch the orientation of a capacitor from  +/- to -/+.

Here is the "normal" model that I have been studying.

simulate this circuit – Schematic created using CircuitLab

Here is the "reversed" model

simulate this circuit

I think the sign would just be negative of the previous.


texts: A standard 1% metal film plated-through hole (PTH) resistor is usually rated at 250 mW. Under which conditions can it handle that power? Are special mounting precautions needed, or will mounting flat on a PCB, with 0.5 mm traces do?


texts:
I'm trying to figure out how to correctly connect 200MHz LVDS oscillator (DSC1103CE1-200.0000T Datasheet) to ICE40LP1K-QN84 FPGA. After reading Lattice's guide to differential signals (Link) this is the routing I've come up with.
CLK_N and CLK_P are connected to IOL_6A and IOL_6B_GBIN7 respectively as recommended in the guide. They are also connected through 100 Ohm resistor (R6). Due to the manufacturing limitations I'm unable to breakout double row QFN-84 package on the single layer, that is why I've routed the signals on the bottom layer.

I would like to know if my routing is acceptable or not. Should I also length-match these two clock inputs? Right now they are 5.39mm and 4.65mm.

Thanks for any advice, it's much appreciated.


texts:
I am a lot confused about how to assign the current of a capacitor and the sign of its constitutive relation, because usually in physics and in engineering there are different conventions. There are some topics here about it but they usually refer to one of these conventions, and I want to understand the link between them and how to apply them correctly.

Precisely, in engineering I have been always told that this convention will work (since it is the passive sign convention, and a capacitor is a passive device):

  Voltage across passive components decreases in the direction of current

So, if we define current and voltage with this polarity (as in picture), we may write that:

It is a very good and practical convention: we know how to choose current and voltage polarities, and their relationship is positive, and there is no ambiguity of sign. I have used it a lot in the analysis of many complex circuits, with also other elements (diodes, transistors etc).

It seems quite clear. But now, let's consider these two typical situations, in which the previous convention is applied:

1) Capacitor charging:

Suppose the capacitor discharged at t = 0, in which the switch is closed. It will start charging and its voltage may be found with the following analysis:

KVL:

Let's put in it the relation:

So:

and finally:

Well, it works.

2) Capacitor discharging: let's apply the previous convention to this new situation, in which the circuit is closed when the capacitor has a certain voltage V0

Let's put in it the relation:

So:

it works: the current is negative, and it is correct because it physically flows in the opposite direction since the capacitor is discharging.

In physics I have seen a different analysis: the capacitor is discharging, and so its constitutive relation will be:

So:

Obviously it does not work. It will work if I take the current in the opposite direction.

So, my final questions are:

1) Which is the link between these two conventions?

2) How can I apply the "physics" convention without sign mistakes?

3) Why does the first convention work also in case the capacitor is discharging, which means that it is working as an active device?

4) How can apply the physics convention in a general circuit (with other components) in which a capacitor is charging at some times and discharging at other times?

5) Obviously I have all these doubts for an inductor too...

About the "physicists" convention, I have found for instance this material (see page 2). It says, about the discharge of a capacitor:


texts:
I am curently working on a project where a MCU got only one UART port available, however I need to run two peripherals with UART interface (not simultaneously) so I was wondering if I can connect two peripherals UARTs on the same UART of the MCU while playing with enabling and disabling the peripherals one by one for communicating with the MCU?

Your feedbacks and recommendation are appreciated about this situation

Regards


texts:
i trying to control 3 phase BLDC motor. I already done 6 step commutation which works fine. Now i going for sinusoidal control. Have studied more about sinusoidal control in bldc and got some idea.

I created sin LUT table for 360 degree using
= 127.5 + 127.5(sin x )       0 < x < 6.28 radians
My table size 2^8=256
table {127,.....255......127......0......127}
By using the table i get good sin wave and i also generated 3 sin wave which are phase shifted 120 degree each other

But i am struggling how to interface this sin LUT with hall sensor angles. I knew that by using PLL logic we can achieve.

Some one clear explain me about hall sensor synchronization with sin LUT. Hope that will help me.

Edited

In the above image, yellow= input pwm to fet & green = phaseA to gnd

The Output wave look ok but motor consumes more than 10amp at 15hz speed. Any guess why its like that. I am confused,.


texts: 3.5mm Stereo to dual 6.3mm mono. Would this work?

texts:
I need to build an adapter which does not seem to be readily available so I can use an audio mixer with my iMac and iPad.

The adapter will convert one 3.5mm male stereo jack to two 6.3mm male mono jacks. One 6.3mm jack will be for the left channel and the other will be for the right.

Would the circuit in the diagram found below work, is it safe, and are there any improvements that could be made?  :

Thanks for any replies.


texts: Gas Tubes: neutralization of space-charge causes drop in tube resistance? Deionizing voltage re-combination?

texts:
The following paragraph is from Chapter 3 of the book Principles of Electronics.

  When cathode is heated, it emits a large number of electrons.  These
  electrons form a cloud of electrons near the cathode, called space
  charge.  If anode is made positive w.r.t. cathode, the electrons
  (magenta dots) from the space charge speed towards the anode and
  collide with gas molecules (cyan circles) in the tube. Fig. 3.5 If the
  anode-cathode voltage is low, the electrons do not possess the
  necessary energy to cause ionisation of the gas.  Therefore, the plate
  current flow in the tube is only due to the electrons emitted by the
  cathode. As the anode-cathode voltage is increased, the electrons
  acquire more speed and energy and a point–called ionisation voltage is
  reached, where ionisation of the gas starts.  The ionisation of gas
  produces free electrons and positive gas ions (cyan circles with +ve
  signs).  The additional free electrons flow to the anode together with
  the original electrons, thus increasing plate current.  However, the
  increase in plate current due to these added electrons is practically
  negligible.  But the major effect is that the positive gas Gas-Filled
  Tubes ions slowly drift towards the cathode and neutralise the space
  charge.  Consequently, the resistance of the tube decreases, resulting
  in large plate current.  Hence, it is due to the neutralisation of
  space charge by the positive gas ions that plate current in a gas tube
  is too much increased.

Why does Resistance decrease resulting in large plate current? My thinking is that if you have a cloud of electrons acting as charge carriers - that would be good for conduction so neutralizing them should increase resistance

  (iii) Once ionisation has started, it is maintained at anode-cathode
  voltage much lower than ionisation voltage.  However, minimum
  anode-cathode voltage, called deionising voltage, exists be-low which
  ionisation cannot be maintained.  Under such conditions, the positive
  gas ions combine with electrons to form neutral gas molecules and
  conduction stops.  Because of this switching action, a gas-filled tube
  can be used as an electronic switch.

Could someone explain why 'conduction stops' with the formation of gas molecules - shouldn't plate current continue to flow?


texts: Why do power diodes have a p+ n- n+ construction and why not p+ p- n+?

texts:
I've been learning about power diodes and how they differ from low power diodes with the addition of a lightly doped n-type layer.
This n-type layer improves the breakdown voltage rating of the device, and improves conduction in forward bias due to the high number of injected carriers from the heavily dopes regions.
Will a power diode work the same if this n- layer is replaced with a lightly doped p-type layer? If it does, why is an n- layer preferred? Or, if it doesn't, why?


texts: AC current in a coil. Why is this statement true?

texts:
I can't understand the following statement:

"A contactor coil with a small control voltage, e.g. 24V AC, consumes
a higher coil current than a similar contactor coil for 230V AC."

Does this phenomenon have something to do with the fact that the self-induced voltage creates a current and that current generates a magnetic counter-flux which weakens the magnetic field in the input? Hence, I think that with the 230V, the counter-current will be higher and so the current in the circuit will be lower. Is this true?

Your answers will be greately appreciated.


texts: Modelling internal fault in a transformer

texts:
I am doing an analysis of faults in transformers and i need to model internal faults in a transformer. Please do advise on how to model internal fault in Simulink.
Thanks in advance


texts: Why does re-seating the battery work to fix a device?

texts:
I have a wireless mouse that is powered by standard AA batteries. Periodically I will go to use the mouse and there's no response. Every time when this happens all I need to do is open up the mouse, re-seat the battery, and then everything works fine again. I want to emphasize that this is NOT simply because I am cycling power. There is a power switch on the back as well, and turning the power off and then on does not fix the mouse.

Why would re-seating the battery make a device work again when simply cycling power does not?


texts: How do I connect this crane machine motherboard to my power supply? What connectors do I need for the power supply header pins?

texts:
I bought a DIY crane machine online and I'm trying to work out how to set up the power supply.
The power supply they provided in the photos looks setup like this, where elements are screwed into the power supply:
https://gyazo.com/b30a3d192a799a9513d32b92e5e4fd9a
In this example above, some of the connections are for the rocker switch & plug. But at the moment, I'm mainly interested in connecting the cables which come from the motherboard in the correct way. The cables that need to be connected to the power supply look like this:

https://gyazo.com/82856b58e3b1f74935cde8b067ac64e3 (The cables in the motherboard)

https://gyazo.com/694600f6beca6003b89fae9a3b11a7ca (The other end of the cables)

The main problem is that the power supply sent to me doesn't have screws like in their example, it just has header pins. This is what the power supply looks like:
https://gyazo.com/29abae5454328bed9581bb0c4f246f75
On the left pins, there is a Molex Housing which fits into this section, but the pins sticking out for the motherboard connections don't make sense to me. I tried buying a 6 way single rail Molex housing with 3.96 mm pitch, but it just doesn't fit and I can't find any suitable female connectors that would seemingly fit this.
So my question to anyone that can help me is: what do I need to get this connected properly and where should the cables go?
Following this, I would also like some advice on attaching the rocker switch, but one thing at a time :D
Thanks a lot for reading if you've made it this far. Any help would be appreciated.


texts:
I'm designing a device that will output TTL (0-5V) over a 50 Ohm coax to an NI PXie-6672 with programmable 50 Ohm termination.
I'm wondering if I will truly need 100mA of drive strength from my output - from what I understand parallel line termination is the standard of most devices, so using basic ohms law shouldn't I be expecting 100mA when logic high?  Or is series termination more common in these devices?  If so, doesn't that cause a reflection?
I don't have easy access to the PXIe's datasheet and the user manual doesn't specify if they use parallel or series termination.
Any help is appreciated!  Simple problem but it has me and some coworkers confused.
-Andy


texts: What is this large metal bar inside my DMMs? One of them labeled it ST. They appear to be connected to the COM port or fuse. Is this just a big jumper for the 10 A ammeter?


texts: Somewhat broken 74HC00 ic. What happened to it?

texts:
I built the following single stepping circuit using a new 74HC00. The inputs for the two unused gates were connected to GND and power decoupled with 0.1uF as close as I could.

The circuit appeared to work but it sometimes produced strange transients (below is an example of one of the more extreme ones). The IC also drew 0.05A which was more than expected. I eventually constructed a copy of the circuit on a breadboard using a different 74HC00 which worked perfectly. No transients, and the power supply showed 0.00A. Dropping in the (desoldered) first IC and I got the transients and the 50mA current.

Is this some kind of classic fault?
Could it be due to my lack of proper ESD practices?
Do you test ICs before?


texts: LED determining Series / Parellel configurations for most efficent design

texts:
My circuit has an input range of 11.8 - 28 vdc. I have 2 types LEDs that I would like to place in this circuit.

The first has a VF Typ of 3.4v and an Idrawnom of .150 A
The second has a VF Typ of 2.2v and an Idrawnom of .150 A

(Link to data sheet)
http://www.optekinc.com/datasheets/OVS5MABCR4.pdf

I have 2 sections in my PCB.

In one section I would like to put 4 of each color.
In the other section put 20 of each of these.

These LEDs could be considered to be on all of the time after power up.

I am trying to figure out what would be the most efficient use of power and determine the series parallel configuration. PWM is a possibility if needed.

The large swing in the input voltage is why I am asking this question. If it were only 12v or 24v then the answer would be straight forward. Also if I was not concerned about efficiency / power distribution it would easy as well.

Also I am trying to stay away from the use of LED drivers vs PWM because of the code rewrite involved.


texts: What is the maximum length a MC68030 can be placed away from Commodore CDTV motherboard, without affecting timings?

texts:
I want to fit a TF536 accelerator card into Commodore CDTV case, which is a challenge from the perspective of available space.

I know there is a relocator board project available, but it still doesn't fit the case. The only way I could possibly make it work is by mounting the accelerator card underneath the motherboard. This would however require an extension wires from 68000 socket of around 3-4 inches (7.5-10cm). Is it even possible to create such extension, and does it make sense? Will I mess up the timings or other parameters of the CPU due to delay (wire length vs traces)?


texts:
I am trying to align a PCBA very accurately (within +/- 0.5mm positional tolerance) on a plastic enclosure. I'm thinking about using two 2mm diameter dowel pin that is press-fitted into the plastic enclosure and then having the two clearance holes on the PCBA align with the press-fitted dowels on the enclosure. Is this a good plan? Any other suggestions of ways to make this work?

Thanks!


texts: How to identify a VCC pin on PCB use digital multimeter?

texts: I want identify a VCC pin in JTAG header on PCB use digital multimeter. The multimeter is entry-level model without continuity test mode, only Resistance mode and Diode test mode. The VCC voltage is 3.3V, but the other JTAG pins (except GND) also have the same voltage too, as it is digital logic circuit. Should I check continuity between supposedly VCC pin and other known VCC power point on the board in the Resistance mode? When checking continuity between two VCC pins, should be board powered on or off?


texts: Why is it a bad idea to divide reference voltage only with resistors instead of using an op-amp buffer?

texts:
I'm planning on shifting the output of an AD8226 instrumentation amplifier by 'about' 0.5 volts using a 2.5 v precision reference and a voltage divider. According to the datasheet this is a bad idea and a buffer must be used:

I understand that if I don't use a buffer I'll probably end up with a slightly different voltage shift and a slight increase in gain. I'm guessing these can be calibrated out by software without a problem. If yes, then why should I use a buffer? Also, there is a note at the last line about a degradation in CMRR. I'm using the device for reading a 0-10 v (very slowly changing) signal in an industrial environment (single ended). Will the CMRR degradation be significant?

P.S. Voltage divider used has two resistors 20k and 4.7k.


texts: Differential cascading of two equal pole Induction motors?

texts:
I was working on speed control of Induction motors through cascading. Theoretically, in differential cascading of two motors, the speed is given by $$\frac{120f}{P_1-P_2}$$
where \$P_1\$ and \$P_2\$ are number of poles. What will happen practically when the number of poles of both motors will become equal. Will the speed saturate and if yes then why?
Precisely, if two same induction motors i.e. having the same rating and number of poles, are cascaded differentially then \$P_1-P_2\$ becomes equal to zero theoretically, giving resultant speed as infinite.


texts: How do I get +5v for loud noise, 0v for silence from Electret Microphone (or other components)?

texts:
I have been asking a few questions here to get to a proper one, the initial questions I asked are linked to at the end. I used Fritzing to make up some schematics of my initial thoughts, but at the very least I need help with the values on the components, which I only vaguely understand and picked what seem to be reasonable or common values.

Basically, I have an Arduino that has 6 analog inputs. It uses a 10-bit ADC to read the voltage on any of the analog pins, so 0 = 0v, 511 = 2.5v, and 1023 = 5v, and all the values in between. It makes a LINEAR DC reading, so I'm not looking for logic 1-0 here.

I have this hooked to LED lights, and I want to make them respond to music. What I want is maximum resolution with minimum components, and I think I'm using WAY too many components and making this WAY too complex. Perhaps Electret microphones are not what I want here, I'm open to something else. I'd prefer to not use op-amps to conserve space on my PCB.

What I want is a simple noise level sensor. I'm not looking to reproduce the audio, or have clarity or anything, but I would like, as close I can get:

Perfect Silence = as close to 0v DC (stable, not AC) as possible
Medium Noise = Around 2.5v DC (stable, not AC)
Loud Noise = as close to 5v DC (stable, not AC) as possible

I understand with a BJT that the best I can get is going to be 0.6v to 4.4v, but this is acceptable enough. What is not, however, is half of the wave, 0.6v to 2.5v. This seems to be wasting half of my available resolution for no reason. However, if there are other setups than a BJT that can get me closer to 0v-5v, I'd be interested in giving them a shot; as long as they're simple.

Here's a simpler one, that I hope that this is possible, but it requires the electret signal to have enough amplitude to drive the envelope detector circuit (diode, resistor and capacitor) to get only the positive half. I don't think it can because of the diode's forward drop, but perhaps this can be rearranged or done before the output cap? What should the values of the envelope detector and amplifier resistors be? Should a sensitivity potentiometer be placed on the signal, or RE, or RL, and what should it's value be? Linear or Logarithmic?

However, perhaps the electret output can't survive the envelope detector, sensitivity shunt, and still drive a NPN transistor. If not, here's a more complex version. Do I need to go this route? Does getting my desired output from the circuit really really require all these components?

Here are some of the past questions I asked before I more fully understood what I was trying to articulate, for more details. Here's what the envelope detector is 'supposed' to do, and I'm not sure how to tune it for the electret output:


texts: Low Current From PNP S8550 Transistor as a switch circuit

texts:
I am using a GPIO pin from the Raspberry Pi to control the Base of a PNP S8550 Transistor and turn an LED on and off. I designed the circuit below:

Base connects to GPIO from Raspberry Pi
Collector connects 5V to LED
Emitter to GND

simulate this circuit – Schematic created using CircuitLab

Yes the Resistor values are correct. I know I am overdriving the LED. LED is also brand new. I want to push 60mA through my LED but the output I am seeing is 3.5mA.

NOTE: CIRCUIT UPDATED


texts: How do flyback diodes (on an H-bridge) affect the motion of the motor?

texts:
I'm designing an H-bridge and one of the features I'd like to have is to allow the motor to keep it's momentum even when the H-bridge is off.

Obviously flyback diodes are used in H-bridge designs to allow the coils to discharge. I feel like I don't have a very intuitive understanding of this concept, but my hypothesis is that this will cause the motor to stop spinning (or at least slow down a bit until the voltage on one of the motor's terminals is no greater than the power supply +0.7V). Is this correct? What does this mean from a mechanical perspective?


texts: Substitute for transistor 2N3904 that is a SMD

texts:
I have the circuit shown below and one of the components (Q2) is a common through-hole transistor.  I'd like to replace this through hole device 2N3904 with a common SMD transistor that will do the same job so that my PCB manufacturer can solder these for me.
Does anyone have a recommendation?


texts:
Recently I've been working on an RC car controlled by a Raspberry pi mounted on an RC car and connected to 2 motors via l298n dual h-bridge
and im using a 12V battery to power the l298N However it only outputs between 2v-1v to the motors and that s not enough to move the car.
So my question is how to controll the voltage output of This Driver ?


texts: Why does amplifier power efficiency not consider the power input by the input signal?

texts:
If we are considering efficiency of a power amplifier, shouldn't I consider all sources of input and output power? Therefore, why doesn't efficiency consider the power of the input signal as follows:

$$\frac{Average \space Power \space of \space Output \space Signal}{Average \space Power\space of\space DC \space Supply\space + \space Average\space Power\space of \space Input \space Signal}$$

As opposed to:

$$\frac{Average \space Power \space of \space Output \space Signal}{Average \space Power\space of\space DC \space Supply\space}$$


texts: LED Christmas lights without limiting resistor

texts: My LED Christmas light strings do not have a series limiting resistor, how is this achieved? They are 70 LED strings with two 35 bulb sections. I have carefully checked and there are no provisions in the plug or inline with the wire. I measured resistance from sockets back to plug and measured no impedance. What am I missing? Can the the LEDS be made (doped) so the internal resistance be high enough that as a group they provide sufficient impedance?


texts: Which side of a PWM MOSFET should an inductor go on?

texts: I have a power supply circuit that needs to supply bursts of power at 5A, 8V but only 1/4-1/8 of the time (using PWM). I wanted to smooth the current draw out on the actual source of the power, a large battery, and I figured an inductor would be able to average out the 5A current draw so that the actual current draw on the battery would be more around 1A or less. I was wondering which side of the MOSFET I'm using to control the PWM I should put the inductor on, whether to put it between the MOSFET and the battery or the MOSFET and the load.


texts: Does the Qualcomm MDM 9207 chip have WiFi, Bluetooth and GPS?

texts:
I am researching about the Qualcomm MDM9207 chip and I have some questions regarding it:

Does this chip contains a WiFi module or do we have to integrate it outside?
Does this chip have a Bluetooth module or we have to integrate it?
Does this chip contain a GPS module or not?

I have researched this and I got some information regarding it but I am not sure whether this is contained in the chip or not.
This is the link: https://www.qualcomm.com/products/qualcomm-9207-lte-modem


texts:
My arduino mega freezes on startup.  I am powering it with an ATX power supply and the Arduino does nothing after power is applied, until I hit the reset button.  I thought the issue was the slow startup but I measured the Power-On Slope Rate to be about 0.56 V/ms which is slow but still well above the minimum 0.01 V/ms for the ATmega2560.

I figured the issue might be the Brown-out Detect threshold, so I used an AVR programmer to change the fuse settings.  I tried 1.8V, 2.7V, and 4.3V BOD thresholds but none of them fix the problem.  Even if it were the BOD, I figure the microcontroller should eventually come out of reset mode.

My first question is: how could I modify the arduino mega board so it will startup reliably?  Is there some capacitance or a resistor I could add to help the microcontroller startup reliably?  Note: using the POK signal is not an option.

Second: if I need to increase the Power-On Slope Rate, what is a method to do this without modifying the power supply?


texts: Bluetooth vs Bluetooth LE susceptibility to interference

texts:
Bluetooth Noob here.
We are currently developing a device which utilizes BLE for connectivity with mobile phones. However, we are experiencing a large amount of interference and broken connections in places were there are a lot of WiFi and Bluetooth devices, such as in shopping malls for example.

The issues include:

Difficulties finding the BLE device during scanning
Intermittently losing connectivity to the BLE device after the GATT connection was established.

We do not experience such issues in a controlled environment such as in a company office or a lab and connectivity is usually stable and fast to establish.

Given that classic bluetooth has 79 channels available instead of BLE's 40, does it mean that classic bluetooth is less vulnerable to interference from WiFi and other Bluetooth devices than BLE? Would it be more reliable in high interference environments?


texts: Improved Howland Current Source not providing less than 1mA

texts:
I've learning a lot about op amps and constant current sources lately. I've implemented the above Improved Howland VCCS. Found it on page 6 of TI's "A Comprehensive Study of the Howland Current Pump":

http://www.ti.com/lit/an/snoa474a/snoa474a.pdf

I see that it draws 1mA/V with loads ranging from 1k to 4k. Which makes sense to me since R13 sets the gain. Yet, for some reason the circuit wont output any current less than 1mA (unless I increase the load resistance above 5k, which isn't important to me). Essentially the relationship of 1mA/V doesn't apply anymore. When I input 0.5mV I still get 1mA out. Same all the way down to zero.

Does anyone know why this might be happening? I'm using an LM741. Do I need to have the exact op amp as seen in the pic?


texts: As i know, we find a thevenin equivalent resistance by finding open-circuit voltage and short-circuit current and then divide these two. I have looked on wikipedia and other sources but could not find an answer. On these websites they only tell how to do it. How opening a circuit and shorting a circuit helps us to find an equivalent resistance? What is a physical fact behind this idea?


texts: Electret condenser: what is the point of this circuit and how to wire it to a TRS jack

texts:
Let's look at the datasheet of a typical electret condenser: https://www.mouser.com/datasheet/2/334/AOM-5024L-HD-R-1219369.pdf

What exactly do the resistor and capacitor do and how does one determine the capacitor value? Looking at the datasheet it looks like the max voltage of the capsule is 9V so adding a 2kOhm resistor limits the current to ~0.4 mA, which is the max current rating of the capsule. So, the resistor is limiting the current to the capsule. I don't understand why we have a capacitor and the physics of the capacitor in this design. Is my interpretation of the resistor correct?
Additionally, suppose we wire this for a 3.5mm TRS or TRRS jack.  Presumably, the tip and ring on a TRS jack both provide a small positive voltage. How does the device separate out the voltage and the output signal from the mic and how is this wired? For a TRRS configuration assuming CTIA standard, I'm guessing the sleeve provides this voltage and also is the output?
Edit: From https://www.epanorama.net/circuits/microphone_powering.html
    +---------------------------- battery +ve (3 to 12 Volts)
    |
   2k2 R1
    |
    o---------- 10uF ------o----- output
    |+                     |
 CAPSULE                  10k R2
    |-                     |
    +----------------------o----- GND, and battery -ve

This is the basic electret microphone powering circuit which you can
use as generic reference when receivign circuits which use electret
microphones. The putput impedance is determined by R1 and R2. If you
leave out R2 the output impedance is roughly the resistance of R2.

Finally, this 10kOhm resistor  connected between the output and the ground, is confusing me, as well as the statement in quotes. What does the 10k  resistor do and how does not including this leave the output impedance roughly half the resistance of R2 (now left out of the circuit)?


texts: The relation between a link speed and Fourier coefficients

texts:
I am reading Computer Networks by Tanenbaum and the the chapter about the physical link and there is an example that I don't understand.

The author states that given a bit rate of b bits/sec the time required to send 8 bits is 8/b bits/sec. thus the frequency of the first harmonic is 8/b.
Then there is an example of a telephone line which have a cutoff at 3000 Hz and claims that the highest harmonic passed is 3000 /(b/8) = 24000/b.

An Example is given for a 300 Bps, the transmission time is 26.67 msec, the first harmonic is 37.5 Hz and the number of harmonics sent is 80.

I understand that a real signal is finite and we can regard it as having a period of some T. I noted that the first harmonic is at 1/T.

I have a few questions:

When sending a stream of data, do we do modulation for some of the bits up to a point and this is the signal we calculate its period etc' ? we can't read all the data to transmit before transmission.
I get that we can reconstruct the signal from the Fourier coefficients. I didn't understand the relation between harmonics and coefficients (does sending k harmonics means sending k coefficients ?)
I don't understand the calculation that was made to get that we can send 80 harmonics in the above example, why does it taking the bandwidth and dividing it to the frequency of the first harmonic ?
Is it possible or wished for that the harmonics sent would not be the first harmonic and all of its multiples up to a certain point ? e.g sending the first harmonic and sending the third one but not the second one.

I'd appreciate an answer to any of those questions, I have studied Fourier analysis but with no relation to signals and real world applications so I'm having difficulties putting theory to use.


texts: Overloading BLDC Motor (Between nominal and stall torque)

texts:
I'm building a robot and want to use a small BLDC Motor.
I want a motor to deliver  1 - 1.1 Nm torque (Before gearing).

If i use a BLDC motor with a Nominal torque (max continuous torque) of 560 mNm, with a stall torque of 7480 mNm.
How do i know how long the motor can deliver 1100 mNm before overheating?

Some specs:
Nominal Voltage: 36 V
Kt= 109 mNm/A
Kv= 88 RPM/V
Stall torque: 7480 mNm
Stall Current: 69 A
Terminal Resistance Phase to phase : 0.522 Ohm.

Thermal Resistance Housing - Ambient: 1.91 K/W
Thermal Resistance Winding - housing: 2.6 K/W
Thermal time constant winding:46 s
thermal time constant housing:283 s

Max Winding Temperature: +125°C

I think the answer has mostly to do with cooling of the motor. How would i go about calculating the time i can overload this motor to 1100 mNm, so i know this motor is suitable for my application?

What do the thermal time constants mean?

Thank you guys very much!


texts: I'm getting a noisey/square wave output for my mux/demux?

texts:
I am using a "CD74HC4051 High-speed cmos logic analog multiplexer/demultiplexer"

I put 5V to VCC, put my oscilloscope probe to the common out/in, put 3.3V to A1 (channel in/out), and have a wire holding 3.3V ready to plug into S0 (address select) so that I can activate A1 from on to off state easily. I expect the oscilloscope to either give me a 3.3V or 0V output depending on whether or not S0 gets a voltage (according to the truth table, S0 on high activates A1).

However when I power the circuit, the oscilloscope outputs what appears as pulses. The oscilloscope also states "Square wave or pulse detected on CH1". When I put 3.3V to S0, another output appears but it's still a noisey square wave.

Any ideas as to why I'm getting such strange outputs? I'm not exceeding the voltage range so I don't think my device is blown?

I noticed the device has a VEE input, should I be putting a voltage here?


texts: Building a "ground plane" for a CB radio

texts:
I'm new to CB radio's and finally setup a home one. The kit I bought was cheap and was made for a car. I got all the wiring done correctly and able to get some fuzz back when I turn the unit on and scroll through the channels.

I'm just realizing now that I need a "ground plane" I large metallic surface to give and receive signals. Normally this would be your car. I have the antenna on my fire escape now, do you know a DIY object I can build / place under it to act as a good ground plane?

Thanks in advance.

The antenna in question is here:
http://www.amazon.com/Cobra-Base-Load-Medium-Magnet-Antenna/dp/B00005N5X2/ref=cm_cr_pr_product_top


texts: Why inductors lose inductance when connected in parallel?

texts:
Generally I can't arrive due to why inductance lose inductance when connected in parallel.

If two capacitors are connected in series, the distance between the plates of a capacitor increase and thus the capacitance decreases, but what happens in the case of inductors?


texts: Doubling RC circuit frequency: troubleshooting

texts:
This is a followup to Is it possible to double the resistance of a potentiometer?, which solved my AB problem of adding a half-tempo switch to an existing beat generator by suggesting that I add a switch + capacitor in parallel with the circuit's capacitor.

I've got the answer from that question and am stuck on the implementation.

Here's the schematic of the audio board I'm trying to alter (area of interest boxed in red):

Here's what I'm trying to do with it according to my understanding of the answer I got for the linked question:

simulate this circuit – Schematic created using CircuitLab

However, when I touch the new capacitor's legs to the existing capacitor while the beat generator is running (to test the effect) nothing happens.

I'm pretty sure

I've identified the right capacitor on the board
The replacement capacitor value is correct
Both capacitors are unpolarized

I don't know

If there's a mismatch in the kind of capacitor on the board vs what I've bought, preventing it from affecting the RC frequency properly because of differing slew rate, hysteresis, etc
How to troubleshoot this further, i.e. what some smart next steps would be :/

Edit:
Here's a photo of the board, with the capacitor in question highlighted:

And here's the full schematic for the rhythm board:


texts:
I'm trying to figure out why the output voltage waveform of this circuit would not include a DC offset of E. My understanding is that D1 becomes forward biased when Vs > E, and so that is when it should conduct. Every waveform drawing I've seen, on the other hand, begins conduction at 0 volts.

Also, what would be the difference between this circuit and one that replaces two diodes with thyristors? I've seen the latter referred to as half-controlled.

Thanks!


texts:
I am a totally beginner in electronics and I am facing a big problem with my prototype. I am trying to create an autonomous circuit that runs an Arduino powered by a 3.7 LiPo battery. The problem that I am having is that after a few days, the battery is discharged even though the solar panel is exposed to direct sun for 7 hours.
The Solar panel Maximum Output Voltage is 5V at a Maximum Output Current of 45.7 mA (  229 mW power)
The above solar panel is connected to a boost converter that outputs a constant 5V and next connected to a TP4056 LiPo battery charge module.
There are some other components like a buzzer, RGB Led, and a Light to frequency converter TSL235L that are connected to the power rails of the circuit.
During the day, Arduino enters in a programmed sleep mode for saving energy. I have constantly measured the voltage in the circuit and it constantly drops from an hour to another with 0.1-0.2V
Is there any problem with the circuit I created or are there any components that are consuming the battery without me noticing it?
Any tips and help will be highly appreciated


texts:
Alright I've been creating some cool stuff in VHDL but I've run into a quirky problem.

I'm creating an ALU, and attempting to write a test-bench for it, but for some reason the timing is off and my signals don't get updated properly.

When I test some logic functions they work properly, but when I reach addition it fails. My inputs update, but the addition of the two inputs doesn't update until the next cycle.

Here is a snippet of the code: "0010" is the control signal for addition.

Here are the signals' values during that cycle: A_ext is in blue, and B_ext is in red, yet the sum vector (brown arrow) has an incorrect value. Its value is actually the sum of A_ext and B_ext from the previous cycle.

And here is the transition to the next cycle. You can see at the brown arrow that now sum has updated to the correct value from the previous cycle.

So I'm a bit confused.  Is this a problem with the way my code is written, or this timing normal in VHDL and there is no way to change it?

Edit

As I said in the comment below, some of the test cases seem to update concurrently however they are in the same process and case statement as the addition test case, the test-bench cases are all coded the same way!

Notice the following picture.  The red arrow points to the first test case, which is:

11111111 (top signal) AND 00000000 (2nd signal)

The result is correctly 00000000 (bottom signal).

The 2nd test case (brown arrow) is

1001100010011000.... OR 1000100110001001...

which correctly results in 1001100110011001...

If the output was updating on the next cycle for EVERY test case, then the output signal above the brown arrow would be the output for the first test case, 00000000..., but it's not.

Here is a larger segment of the code. I've been using 33 bit signals, A_ext and B_ext, for the addition of the 32-bit signals, A and B because to be quite honest I don't know any other way to do it and catch the carryout bit but if someone does know a better way, I'm all for it!


texts:
im working on a solid state tesla coil project,so i have a inverter ic

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.alldatasheet.com/datasheet-pdf/pdf/512032/POWERINT/TNY274PG.html&ved=2ahUKEwixwcSNn_LoAhULXSsKHeeuCcYQFjAMegQIBBAB&usg=AOvVaw2hCcPIbN5UCF-J_L_MQYgQ

Here is the datasheet for the ic so the question is can i apply a signal to the en/uv pin and use it to drive the gate drive transformer


texts: maximum via current carrying capacity pcb

texts:
As I know, there exist limits on maximum current, a pcb via can tolerate before it melts before the via's temperature rises unacceptably high above ambient (say 10-100 C above ambient depending on application).

What are standard values or rules of thumb for the maximum current (or current density) through a pcb via?

PS: the question is about DC, but any additional considerations (if any) for a high frequency current are welcome as well.


texts: How can I constraint placement of design inside a specific slice using the LOC constraint with only mentioning Slice

texts:
My design takes up 4 LUT so it can be placed in one Slice. I want the placement in specific locations. Since my design is parametric, I want to just instantiate multiple instances of the Module and pass the Slice Location in a parameter as LOC=SLICE_XnYm .  I don't wanna mention which Cell is taking which LUT.
I want to only provide Slice information.
with only using the LOC=SLICE_XnYm  inside the module, It show some some LUTS in Cyan and some in orange. Cyan as Placed and Orange as Fixed. Will it make any issue?
ro.v
`timescale 1ns / 1ps

(* keep_hierarchy = "yes" *) module RO
#(parameter SLICE = "SLICE_X43Y0")
(
(* dont_touch = "true" *) input enable,
(* dont_touch = "true" *) output clk

);
(* LOC = SLICE *)
// Intermediate Connections
(* dont_touch = "true" *) wire w1,w2,w3;

(* dont_touch = "true" *) and #2 (w1, enable, clk);
(* dont_touch = "true" *) not #1 (w2,w1);
(* dont_touch = "true" *) not #1 (w3, w2);
(* dont_touch = "true" *) not #1 (clk, w3);

endmodule

top.v
`timescale 1ns / 1ps

    module top(
            output out
        );

    wire enable, clk1, clk2;

     RO  #(.SLICE("SLICE_X0Y99")) R0(enable, clk1);
     RO  #(.SLICE("SLICE_X0Y98")) R1(enable, clk2);
    endmodule

and the placement after implementation looks like this:

Why the two LUTs are placed in other slices?
It should look like this, and also in the status should be Placed (Cyan).

Update: If I use SLICEL slices then the placement is OK, but It's status is  still Fixed not Placed.


texts:
How do I work out the optimum charging amps for a life 2p4s battery?

I have 8 x 66ah sinopoly batteries.
http://www.sinopolybattery.com/userfiles/files/SP-LFP66AHA.pdf

Charge Specs
* Standard Current 22A CC&CV
* Max. Current 132A 2C
* Limited Voltage 3.65V
* Cut-off Current 2.18A 0.033C

As I have 2p4s making 132ah is the max current 132ah x 2c = 264A?

Is the "standard current" the optimal charging? Is it now double to 44A?


texts: What is the purpose of transistor and zener in this circuit?

texts:
simulate this circuit – Schematic created using CircuitLab

(simulation will not be correct because the diodes are added just by its name.)

Hello, I am a student who is not really familiar with electronics, and these days I start studying several circuits which is being used in our experiments.

I have a circuit we insert between room ground and the circuit with power supplies. I made a diagram from the photo of the circuit that I took.

As far as I know, to avoid too high floating voltage between the circuit with power supplies and the ground, the circuit is to make negative voltage ~ MAX -50V relative to ground. (Zener diode 1N5347B are actually 5 in series, not one. I omitted for the simplicity in the diagram)

I sort of understood by Googling and learning myself that the capacitor and the diode is a safe circuit for sudden voltage peaks (am I right?)
But, the center part in the circuit diagram, still no idea after several days study. Only figured out that 1N5347B Zener diode 10V 5W  is to endure max -50 V.

Here are my questions..

What would this circuit be called, if it has a name?
How may the capacitor size 1 uF and resistor size 10 ohms be chosen?
Why and in what role are those resistors (cement resistors) and transistor connected additionally to the zeners? I thought to have max -50V, only the 5 zener diodes may be sufficient.
Is it sort of isolation circuit or floating regulation circuit?

----------------------added at 20:52 pm, 6th March, 2016 ----------

Thank you for all who had commented.
The following figure is the edited schematics.
U1 - U3 are some user equipment boxes powered by DC power supplies 1, 2, 3 sharing Vcg with their '-' port. (PSs have '+, -, GND' ports, and'GND' ports in PSs are not connected to its own '-' ports.)
So, the right side of Vcg are grounded, not to earth, but to the node Vcg.
The circuit in the photo is the left side of Vcg.

simulate this circuit

So far what I learnt about the circuit (left side of the node, Vcg) are,

to keep 'Vcg' negative potential relative to earth. (which doesn't really have its own power supply), but up to max ~ -50V.
thanks to @transistor, the roles of the capacitor, diode, and shunt regulator.

Here, additional questions came up to me.

What role does the circuit itself have when it doesn't have a power supply to itself? would it be just being connected between Vcg and earth, and would start work when Vcg tends to go further negative than -50V?
In what case (I guess, when what happens in the right side circuit for operation of equipment), Vcg would tend to go more negative?
and let's say when it goes -51V, without any power supplies on the circuit, the current through R2 to turn on Q1 is going to come through the earth?
What kind of improvement would I be able to make for this circuit?

(from the previous question)
5. How may C1 1 uF and R2&R3 10 ohms have been chosen? (got to know about R1 to limits the current through D2, thanks to @transistor)

p.s. Am I asking too many questions in one? is putting additional questions not quite the thing?

-------------10:34 am 7th March 2016, updated--------

I think @transistor answer makes sense, and I understood its role. But my schematics may have error still, and the figure in p. 338 doesn't show clearly how the circuit will be closed during the thruster operation, I am trying to give as much information as possible. @transistor mentioned about 'closing circuit', and I added a drawing for that. Generated plasma near anode (inside in U1 in the drawing) accelerate to the vacuum chamber wall which is earth ground, so I expect this is the mechanism closing the circuit.
In the drawing, the big square grounded is the vacuum chamber.
I hope this help to comprehend the circuit for the additional questions.


texts: Can anyone help me identify the kind of connectors in the pics below? Both the male and the female version. In case it helps, these are used in an LED fixture, to connect the (DC) output of the LED driver to the LEDs themselves. They are relatively small, roughly 15mm by 5mm by 2mm.


texts: Why is my fan circuit with SSRs short circuiting on power down?

texts:
I am attempting to build a "smart" ceiling fan for a home automation system I have created and added to over the years.  However, this is the first time I've tried controlling a fan motor and the first time I've used solid state relays (SSRs).  My research (and now experience) shows me these two elements can be a bit tricky.
Note: I am a software developer with no formal electrical engineering education so you will forgive my ignorance when it shows.
In brief, the system powers on fine and can be controlled by my software running on a NodeMCU successfully.  It can do this for several days.  However, at some point, during a power-off cycle, the circuit will short and blow the fuse.  Once this occurs, 4 of my 8 SSRs will be permanently closed.
I am very confident the short is occurring during power down (i.e,. while turning off the wall switch that provides 120v to the black (#6) wire as seen in the attached SmartCeilingFan schematic).  This is true because when I had it on my bench testing it, I saw a blue flash from the fuse when I turned off the system after a successful test run.  After that, the SSRs mentioned below were permanently closed.  (This has occurred on three different prototypes I have done so it is clearly repeatable.)
Troubleshooting I have done:

I have placed an oscilloscope on all of the used data pins on the NodeMCU and confirmed their behavior on start up to be as I state in the attached SmartFanWifi image.
I have placed an oscilloscope on the data pins for both of the SSRs I suspect to be coming on at the same time and causing a short and confirmed that neither bounces HIGH during power down.
I have gone over the G3MB-202P datasheet and the SSR's Common Precautions sheet in detail.  However, this is where my lack of formal electrical engineering training will show... while I believe I have followed the guidelines and am in spec for the SSRs, I somehow must not be.
I have bench tested the max amp draw of the ceiling fan by placing an amp meter in series on the load side of the fan and then held the fan from spinning (not a perfect way to do it I am sure, I'm willing to be taught).  The max amp reading using the method was around 500 mA.

Additional information:

The ceiling fan is a Hunter fan with this wiring diagram out of the box.
Here is the datasheet for the L293D ICs.

SmartCeilingFan Schematic Image

SmartFanWifi Schematic Image


texts: Why is 3-chip forward current less than 1-chip in RGB LED LTRBR37G?

texts:
Why is the forward current of 3-chip operation less than forward current of 1-chip operation? (Page 3 of datasheet.)

https://dammedia.osram.info/media/resource/hires/osram-dam-6751107/LTRB%20R37G_EN.pdf


texts: Understanding time constant of high pass filter at op amp input

texts:
In the circuit attached R17 is the burden resistor for a CT which measures 50/60 Hz currents. The switch is a CMOS analog one, not electromechanical.

When the switch is closed, the gain is about R16/R14 = 49.9k/832 = 60. When the switch is open, the gain is R16/(R14+R15) = 49.9k/(832+49k) = 1.

The cutoff frequency of the low pass filter is 1/(2pi*R16*C17) = 678 Hz

Now my question is about the AC coupling cap which forms a high pass filter.

When the switch is closed, the cutoff frequency is 1/(2pi*R14*C18) = 4 Hz and time constant RC = 39 ms
When the switch is open, the cutoff frequency is 1/(2pi*(R14+R15)*C18) = 0.068 Hz and time constant RC = 2.34 s

Is there a negative effect of these time constants on my 60 Hz signal (16.67 ms period)?


texts:
I have a radio transmitter and a radio receiver .

simulate this circuit – Schematic created using CircuitLab

Will the sound produced by the loudspeaker have the same frequency with the tuning frequency?


texts: Change same signal at either rising or falling state of a signal

texts:
I am bit new to VHDL, and hope some of you guys could help me here.

I trying to establish a connection between an ADC, LED, and control component.

The purpose of this application is to convert an analog value measured on the ADC, and then output to the LED.

The way i've designed the communication is as follows.

The LED set and signal high (start_adc) Which the ADC read, and start the ADC.

When the ADC is done, it sets the signal read high, which Control then reads, and then read the ADC_value ( a binary value - std_logic_vector (9 down to 0)).

This ADC_value is kept within control, but the LED has to change its state. So Control set the signal next_state high, which LED reads and changes its state to something  else.  The problem here is how do i turn off next_state?.

My solution entailed the use of a signal named received which would be set high, if an rising_egde(next_state)was seen such that, if control saw an rising_edge(received), it could then turn off next_stateand then when LED shaw and falling_edge(next_state) it could set received low again, and then start_adc high.

code wise it looks like this

state_changer: process(clk,state)
variable count: integer range 0 to 500000000 :=0;
begin
     if falling_edge(next_state) then
       received <= '0';
       start_adc <= '1';
     elsif rising_edge(next_state) then
       received <= '1';
        count := 0;
        start_adc <= '0';
     end if;
     count := count +1;
end process;

but as you can see the problem is that the same signal is set either at rising and falling..  how do I work around this issue?..

Notice count is also important.


texts:
I'm sorry for asking a question this simple but I can't understand it .
Single phase ac has two wires , phase and neutral but I don't know which wire change voltage . Like neutral wire is always 0 v and phase wire changing +V to -V or phase and neutral changes direction ? (Like phase +V , neutral 0V then neutral +V , phase 0V ).
Also what's the difference between pulse signal and ac ?


texts:
I have a 6V input on my board. I need to put a load switch for USB 3.0 which needs 5V. I need to stepdown 6V to 5V using a series diode. 6V is going to other circuits also.

Can someone suggest the diode I can use & what parameters should I consider while selecting a diode.


texts: How to choose appropriate DC-DC converter for Electric Vehicle battery charging application?

texts:
I'm currently working on a project which requires building an EV battery-charger as a starting point. At present, I wish to design it for a 220 V, 50 Hz grid source input. The nominal voltage of the battery pack is 82 V, and nominal charging current is 80 A.

The DC-DC converter has to be in current-controlled mode (for 80 A constant current). The top-level schematic is as follows:

However, many guidelines on the web suggest that buck converter is not a suitable choice for high power applications:

https://www.we-online.com/web/en/passive_components_custom_magnetics/blog_pbcm/blog_detail_electronics_in_action_45887.php
https://www.smps.us/topologies.html

Why won't a buck or isolated-buck be sufficient?


texts: Whats the easiest way to make an antenna for a given radio

texts:
I am trying to make a PCB for the nrf8001(http://www.nordicsemi.com/eng/Products/Bluetooth-R-low-energy/nRF8001). The IC has all the radio transceiver parts , however it requires an external antenna. Its small scale. A maximum of 50 pieces is all I will be needing. I was thinking whats the best approach I should take? Should I use a ceramic antenna or a PCB trace antenna. (Its for 2.4GHz and cost is definitely a factor which needs to be taken into consideration.)
Also I was wondering how the nrf24l01+ is available for such a low price. The IC is cheaper I agree , but for me to just make the board itself is extremely expensive  compared to the value of the entire breakout nrf24l01+ board? How do people achieve such low cost?(Ebay-Link which shows the low price of nrf24l01 breakout board -http://www.ebay.com/itm/2pcs-NRF24L01-2-4GHz-Antenna-Wireless-Transceiver-Module-For-Microcontr-/251044600998)

I have also looked at https://github.com/nabilt/nRF8001-Breakout-Board but it seems to expensive for what I am looking for. Whats the best way for me to proceed?


texts: Simulating TFT LCD (ILI9341) With Proteus V8.3

texts:
I am using Mikrobasic for AVR, and Proteus V8.3 ,So i have wired my circuits as you see in this picture:

I modified it in Proteus with one IC Atmega128 as you see in this picture:

and i used this code in Mikrobasic for AVR :

    program MyProject
 '*******************************************************************************
'----- Color LCD CONFIG --------------------------------------------------------
'*******************************************************************************
 ' TFT display connections
dim TFT_16bit_DataPort_Lo as byte at PORTD
dim TFT_16bit_DataPort_Hi as byte at PORTE
dim TFT_16bit_WR as sbit at PORTA1_bit
dim TFT_16bit_RD as sbit at PORTA2_bit
dim TFT_16bit_CS as sbit at PORTA3_bit
dim TFT_16bit_RS as sbit at PORTA0_bit
dim TFT_16bit_RST as sbit at PORTA4_bit

dim TFT_16bit_DataPort_Lo_Direction as byte at DDRD
dim TFT_16bit_DataPort_Hi_Direction as byte at DDRE
dim TFT_16bit_WR_Direction as sbit at DDA1_bit
dim TFT_16bit_RD_Direction as sbit at DDA2_bit
dim TFT_16bit_CS_Direction as sbit at DDA3_bit
dim TFT_16bit_RS_Direction as sbit at DDA0_bit
dim TFT_16bit_RST_Direction as sbit at DDA4_bit
' End of TFT display connections
 ' TFT display connections
 dim
  TFT_16bit_Disp_Rotation as byte
' End of TFT display connections

' Declarations section

main:
     TFT_Init_ILI9341_16bit(  240, 320)
      TFT_16bit_Dot(50, 50, CL_WHITE_16bit)
      TFT_16bit_Fill_Screen(CL_AQUA_16bit)
end.

So if the connections is correct it must show an blue page in Proteus simulator,but it don't work.!!!

so you could find the Hex file and Proteus file here:

http://www.mikroe.com/forum/download/file.php?mode=view&id=12099&sid=ed3ccf136cea56f86f33688e91ce2a88

So i think that i have wrong in Proteus connections for TFT LCD ILI9341.!!!
But what is the correct connections?!!!

Thanks a lot.


texts:
I would like to know which sensors should I use in order to get measurement of a movement of my device (slow speed movement on a 2D plane, in cm or mm if possible). The goal is to find out if the user has moved the device from a starting point and to calculate the distance between the two points.

EDIT:

The plane will be 2.0m x 0.5m. It will be a device held by a person that will begin the "measurement" at the intersection of the diagonals of the plane. The user can lift the device.  I can't tell you exact the speed right now - just a slow hand movement (but the speed will not be constant).

I would appreciate any advice on a device that could rotate; But in this case I am asking for a non-rotating device (there will be single point to track). There are no cost restrictions, the smaller the device, the better.


texts:
What type of electrical motors are on the movie?

On the Youtube video they use commercial off-the-shelf consumer fans.

There is a control system - which is basically 4x OptoCoupler + Triac + (resistors and capacitors).

Those two motors on the movie are so nicely speed adjustable.

What they are, out of:

single phase ac motors

Split-phase motor
Split-phase start capacitor motor
Split-phase run capacitor motor
Shaded-Pole motor
Universal motor

for sure this is NOT no.5. (because they are specifically loud)

It seems that this is NOT no.2 neither. In the publication, author try to achieve the same, but withouth successful results (p.23-27), on page page.14 he states that this is 'Single Phase Induction Motor / Capacitor Start Type Motor / 370 W'
https://es.slideshare.net/VISHNUG39/automated-speed-drive-using-raspberry-pi

Which of those motors form the list (no.1-no.5), ventilators on the youtube movies are then?