texts: How to drive 30 LEDs with a smaller amount of pins?

texts:
We have 30 LEDs in a row, and we want to turn them on left to right. However there are way to many for the Arduino to have each one on a different pin.

Is there an IC that can take a binary output, and output in base 1?


texts: Thin plate piezoelectric transducer glued to flat surface in shear mode

texts:
I want to glue a piezo plate looking like in the image below such that the wide surface of the plate gets glued onto a flat surface. The image is part of the datasheet from here.

If I apply an AC voltage to the piezo plate such that it starts expanding and contracting along the flat surface it's sitting on, will the plate fall off?

I have no actual experience with piezo and wanted to see if gluing a thin piezo plate on a flat surface and have it expand parallel to the surface it's sitting on is feasible.
The 2nd image below is what I want to achieve and I was wondering if it really does happen without changing the height  (if it really does only move laterally)

(the 2nd image is from here)


texts: Thermistor control of peltier voltage with Arduino (for DSLR chill box project)

texts:
I am mildly familiar with electronics, mostly from playing around with electronics kits as a kid. That was a long time ago, though, maybe as much as 20 years ago. I am currently working on a cold or "chill" box for my Canon 5D III, so I can keep it's temperature very low, and very consistent, for doing low noise astrophotography.

I have a general design for the box, and I'm using a single 12v 5.8amp peltier (TEC) attached directly to a copper box for cooling. The box is currently insulated with extruded foam board, and the hot plate of the peltier will be cooled with a water cooler from an old computer kit.

I'm getting more ambitious with my project, however. I want thermal regulation, to maintain a consistent temperature, and I'd eventually like to get into two-stage cooling to achieve a Delta-T of closer to -55-60°C relative to ambient (the chill box will be cooling the camera, so the sensor will be warmer, probably by as much as 10°C, than the temperature of the copper plating in the box itself.) I want to have two primary modes:

Rapid cooling mode, operating the peltier at 12v or higher (max voltage is 15.4v) to quickly cool the box down to the target temperature.
Regulated maintenance mode, operating the peltier at lower voltages to maintain a consistent temperature, above the maximum potential cooling the peltier can supply (for headroom as the voltage is adjusted in response to small temperature fluctuations).

I'd like to maintain temperature within 2-3°C if possible. I've looked into Arduino (and I've messed with similar things in the past), and it seems perfectly ideal for the task, with one exception: It doesn't seem to handle the kind of current I need top power a single peltier, and certainly not two.

I've done some research on how I might achieve this, but I'm falling up short on my understanding of the electronics involved. I've found a two-relay "shield" for Arduino Uno that can power two devices with up to 8amps each, and up to 30v each. That can be controlled from the Arduino itself. It seems the design of a relay uses a magnetic coil to actuate a switch that allows an independent power source to be used to power components like a motor, solenoid, or in my case a peltier. I haven't found any way of actually regulating the voltage of the relay with the Arduino, however.

So I kept investigating, and I came across some schematics that showed how to use transistors, specific mosfets to be exact, where the base was connected to an Arduino output, and the collector/emitter were connected to the power loop of whatever needed to be powered at a higher voltage (not sure about current here), and this still allowed control of the voltage.

It's been so long since I messed with any of these components, my memory is extremely rough, and I'm not quite connecting how it all works. I'd be happy with some references to complete examples of powering, and controlling the voltage of, high powered devices via an Arduino, but if anyone here can explain how all this works and why, that would be most ideal. I'd rather understand the concepts, so I can reapply them later, than just have a pattern to follow.


texts: Have bypass cap recommendations already taken derating into consideration?

texts: Datasheets often specify specific values for bypass caps. My assumption is that these values reflect the actual value (after derating), however, I often see on evaluation boards the same nominal value components being used. X5R caps can lose up to 80% of their nominal value under normal dc biases. How are recommended values in datasheets supposed to be interpreted? I can upload specific examples if necessary.


texts: Power calculation for AC signal at the rectifier input

texts: I am working on the design of rectifier using MOS in Cadence ADE. The AC signal amplitude is 415 mV at a frequency of 865 MHz. The current is 14.5 mA. Now, the dDC voltage is 400 mV and the load current of 2 uA. Can you please let me know how to calculate the efficiency? PCE is the DC output power / ac input power. How should I calculate the ac input power? The values which I had mentioned above are not the RMS values.


texts: Regarding transient analysis of RC circuit

texts:
Here I am trying to find the input current I(t) and Vc(t).
From my calculation, it's evident that Vc(0+)=Vc(0-)=0V and Vc(∞)= 10V but I am confused about the first capacitor. When t=0, it acts like a voltage source of 10V but does it supply current to the 2nd capacitor? The second capacitor was shorted when t=0+,then I(t) was flowing through it. Hence,I(0+)=10V/5kohm=2mA.also I am confused about the time constant of the circuit. According my assumption, C1 acts like an independent voltage source from t=0- to t=∞. Then would the time constant be (5*2)=10? Is my assumption correct?


texts: I am trying to make a OBD logger for heavy-duty vehicles

texts: The thing is that I have to use one CAN transceiver and one CAN controller. Both have one interface (CANH and CANL). I use dip switches to route different CAN signals whenever I need to using a DIP switch.


texts: Can I use a common Clock pin on my micro-controller project instead of separate clock pins?

texts:
In my Propeller project, I have the following devices, with the related pins:

DS1302 RTC

SClk - IO - CE

Micro SD Card

SClk - CD - CS - DI - DO

SPI SRAM x 2

SClk - SO - SI - CE

PS2 Mouse

Clock - Data

PS2 Keyboard

Clock - Data

Eprom

SCL - SDA

Right now, each one of these is individually allocated a Clock Pin,
What I would like to know is if I can merge all of the clock pins into 1 single pin
And re-use the other spare pin for extra devices?

Even if I need to introduce a transistor to boost the signal (So I am guessing, this is what may happen that there is not enough signal to service all the devices and I need a transistor? - I don't know I'm just guessing since I have no formal grounding in electronics)

For reference,
This is the link to an earlier post (different question) on stack electronics which shows my actual circuit/schematic

https://i.stack.imgur.com/pdCgo.png

Thank You


texts: Altium PCB Footprint Component Size Does Not Interpret Text Properly

texts:
I have just updated from Altium 17 to Altium 18 and I am seeing a strange behavior where the special string text overrides the the actual size of the text.

This special string text size is being interpreted as part of the entire component, and therefore I am getting DRC errors.

I have attached in image that shows the the designator (U29) is completely inside the part, but when the part is selected, Altium interprets the size of the component with the special string ('.Designator') and is therefore much larger than it needs to be.

I had this issue in version 17 as well, but I don't remember how to change that setting.


texts: How can I manipulate timer1 / timer2 in arduino nano to get HS PWM?

texts:
I'm new to arduino but have coded a few projects in AVR ASM years ago.

Now I'd like to manipulate t1/t2 to get high speed pwm. I can lower the resolution from 511(?) to 63. And maybe mess with the prescaler. It would be nice if millis() are left intact. Can it be done, or do I need to get out of the arduino umbrella?


texts: Clarification of an answer about CT sensors and diagram

texts:
Hi I have found a perfect answer that clears the purpose of the parts in the schematic.
So two resistors and arduino 5v source adds up to the negative side of the AC voltage.

Is there any "special" name or this kind of circuit where you add  aditional "control" voltage?
How can DC voltage be added to AC?


texts: What are these components in block diagram of STM32?

texts:
Today, when I was seeing in STM32F103RET6 datasheet I saw some odd things(also, they are odd for me, probably you have enough information about these). if look in 12P of datasheet, you will see this picture:

I have determined 3 point of it and have several question about these three point:

for number one: What is this part and What does it do? (I mean "Obl")
for number two: How does this power switch work?(I mixed up, Does it work automatically?)
for number three: What's the mean of the "IF" word? If you consider, even, you will see the "IF" for ADC units(not just for DAC).


texts:
I just read about commutators and their uses in motors and dynamos. While revising the topic I came across this question:

According to me the answer should be (c). Because:

In the above diagram of dc motor the direction of current in coil changes from ABCD to DCBA.

Similarly, in the dc generator shown the direction of current in coil changes from DCBA to ABCD.

But the answer according to the book is (a). This makes me wonder if I missed something in the concept.(or if the given  answer is wrong, which is less likely)

Can somebody please clarify.

Thanks


texts:
Anyone care to explain how this piece of circuit work?

I already build it and it works wonders but I can't figure it out.


texts: How are interrupt handlers implemented in CMSIS of Cortex M0?

texts:
I have a LPC1114 kit. Last few days I have been digging up CMSIS implementation of Cortex M0 to find how things are done in it. So far I understood how each registers are mapped and how I can access it. But still I dont know how interrupts are implemented in it. All I know about interrupts in CMSIS is there are some interrupt handler names mentioned in the startup file. And I can write my own handlers by simply writing a C function with the same names mentioned in the startup file. What confuses me is that in the user guide, it is told that all GPIO can be used as external interrupt sources. But there are only 4 PIO interrupts mentioned in the startup file. So tell me:

How can I implement external interrupt handlers for other GPIOs?
Where is the interrupt table mapped in the CMSIS?
What are the major differences between NVIC and the interrupt implementation in AVRs/PICs? (except NVIC can be mapped anywhere in the flash)


texts: If 2 lamps of same power are connected in series, the first one connected glows better and the next one gets dimmer..then Why doesnt the serial lights( Christmas lights ) get dimmer even though they are connected in series and share the same voltage..??


texts: Pros/Cons of using a Power MOSFET vs. a standard MOSFET

texts:
I recently sought (and received much great help) help with a brake light project from this site.  That project went well and I installed it a week ago.  Everything seems to be working as intended thus far.  However, I am interested in playing around with some potential variations to the design of the circuit.

I ordered most of my parts for that build online from Digi-Key and Mouser.  However, I did not have enough extra VN10LP N Channel MOSFETS to complete an identical circuit.

I went to my local RadioShack today and got 4 N-Channel power mosfets to hopefully use in place of the VN10LP mosfets.

My application is straightforward: the n-channel MOSFETs are being used simply to provide HIGH or LOW signal to pins on an Octal Counter IC.

Looking at the ratings of the power mosfet, all of the ratings are more than adequate for the circuit's current and voltages.

Therefore, are there any potential pros/cons to using a POWER MOSFET versus a regular MOSFET in a simple, low speed switch application??

Data sheets for each:

VN10LP N Chan MOSFET VN10LP

IRF510 N Chan POWER MOSFETIRF510


texts: Unexpectedly poor DNL, INL and ENOB on an ADC

texts:
I'm currently trying to characterize an MCU and it's peripherals, in particular the on-board ADC. However, running the usual test procedures (i.e. sine wave for ENOB and sawtooth for DNL and INL), I find that the results are rather poor. Long story short, the ADC "is" 12 bits - meaning one would expect around 10 bits of resolution out of it. However, no matter what I try, ENOB seems to plateau around 8.5 bits. Similarly with the DNL and INL - the best results I've been getting are when the signal is oversampled 64 times. The datasheet on page 44 does say that one may expect DNL of around ±3 LSB - however, this is what I get when I oversample. The raw signal peaks at about 7 LSB. There are a few things that I tried so far:

Putting a 10 nF capacitor across ADC input and ground (which does work to some extent - without it ENOB is 7.5)
Oversampling 4x, 8x and a few others up to 256x. This - as one might expect - also improves results, although not as significantly. Larger oversampling produces better results whereas 4x is almost identical to no oversampling.
Slowing down the ADC module clock and increasing sampling window. None of these were particularly effective. Increasing the sampling window had a small positive impact on ENOB and DNL. Slowing the clock down didn't really have any effect.
Similarly, using external or internal references did not seem to produce an effect, although I haven't done a lot of experiments with external reference - maybe that's the next one to consider. A small edit for the reference of whoever may read it one day - using an external reference in my case yielded worse results. In other words, the internal reference on my MCU seems to be more accurate - or external reference isn't as good as I expected.

Now, the question is at which point does one accept that the ADC is just of poor quality or somehow damaged? What other tests can I try to improve ADC characteristics. Note that I generate the input signals with the function generator. At this point I am just stuck - i.e. ran out of forum threads to read - and I would genuinely appreciate any advice.


texts: Considerations when using internal pull-up/down resistors

texts:
I am working with STM32 micro-controllers. These micro-controllers have the option to set the input pin as pull up or pull down:

Earlier I used to give external pull up or pull down resistor wherever required but now I am wondering whether I can do away with external components and use the pull down feature of the micro-controller itself.

Will that be a good thing to do?

Is there some use case where I should take extra precaution or not use this feature at all?


texts: How do you calculate the output voltage of a discontinuous inductor boost converter?

texts:
When designing a boost converter to take a low input voltage to a high output voltage, there are many knowns that you control, such as the choice of inductor and the duty cycle of the switching that is at the heart of the boosting voltage. The below circuit is a demonstration of what I'm talking about - no values since its not a question about specifics.

If you're running the boost converter in discontinuous mode, with a known duty cycle and period (\$D\$ and \$T\$ respectively), input voltage (\$V_i\$) and inductance (\$L\$), you can calculate various important values such as peak current through the inductor. But the sticking point that I keep arriving at is how exactly do you calculate the output voltage over a theoretical load, R? Or, as I'm being led to believe, does the output voltage/current actively depend on the value of the load R?

Much of the literature I read assumes that you know \$V_o\$ and \$I_o\$ already (which when you're designing this, it does make sense to know what your desired output is), but I'm approaching this as if I don't, yet not getting anywhere, since the equation regarding the voltage gain:

\$ \dfrac{V_o}{V_i} = \dfrac{V_i D^2T}{2LI_o} + 1\$

includes both output voltage and output current, which seem to depend on each other from other equations:

\$I_o = \dfrac{I_{max} \cdot \delta T}{2}\$

which if you sub in the equation for \$\delta T\$ and \$I_{max}\$ just results in the first equation. I can't find a way of isolating one variable. Trying to equate the energy across the capacitor similarly isn't leading me in the right direction.

What I don't understand is that for the given four variables at the top of my post, I'm left with the output voltage and current as free variables, which leads me to posit that these then must depend on the load? Is my thinking correct, or do I misunderstand the concept of what is going on? I know I'm going about this the 'wrong' way, it's just a curious thought experiment as I'm trying to make sense of other circuits, where the PWM/duty cycle switching and other components are already set.


texts:
I have a project that uses a computer case and PSU, but not motherboard, to turn on the PSU,  all we know is to put green cable to GND.

The problem is the ON Button, it's momentary and I need to keep the PSU on. I've seen some circuits with arduino but because the price its not an option (50 USD arduino).

Any ideas?


texts: Refrigeration compressor circuit, help trying to reverse engineer it

texts:
I have disassembled the motor controlling circuit for my refrigerator.
I am trying to understand how it works, so I hopefully reduce the start surge-current and make it work with my 1000w inverter. Currently the fridge sometimes draws 1100w on start, othertimes only 600w.

The fridge is brand new, high-efficiency, "BEKO" with a Donper AG100CY1 compressor.

I've checked the circuit a hundred times, and it really is like this:

simulate this circuit – Schematic created using CircuitLab

But it seems to go contrary to what I've read about refrigerator controller circuits.

The start winding is permanently connected (normally it would be disconnected after start, e.g. by a PTC)
The run winding is current runs via PTC at start, then via capacitor once hot

My main surprise is that the surprise winding is permanently connected.

(And additionally, I am hoping to add a start capacitor...)

Why isn't the start-winding disconnected? Does this make any sense?


texts:
Are there any circuit template I could look into if I want to achieve the following specification stated below:

Input: 5VDC
Output: 1kV, 0.5mA

I was looking into the flyback convertor but I am not sure if it will work out. Please help me out.


texts: Embedded board level functional test at factory

texts: My embedded project has a GSM and a GPS module. What is the best way to test the radios of these modules after the production of CCA like in a factory conditions.I was thinking of signal generators transmitting at the required frequencies. Is there a better way to solve this problem?


texts: Switching from different sources using a microprocessor

texts:
What I want to be able to do is have a way to switch between different 3.7 volt lithium batteries to charge them and monitor them and be able to have them connected in series through switching as well. I want to be able to control all of this through a microprocessor.

What type of switch could be used for this?


texts:
The figure shows a modification, from state A to state B, carried out on the cell at the output of circuit (X).
In both cases, the voltage at point A is the same. The transistors M1 and M2 keep the same dimensions.
How to define or calculate the rise time of the signal at point A?
How to explain or how to define the decrease in current through M2?
Thank you.


texts: Can a 3.3v logic i2c be directly connected to 5v logic i2c

texts: So can a 3.3v mCu directly communicate via i2c to a 5v mCu ? the buss will be pulled to the lower voltage 3.3v. And since i2c protocols involves just sinking current is what makes me think it will work


texts:
Does electric motor reactance at given speed is constant according to rotor position (angle)?

For switched reluctance it is not. But for three phase induction motor?
Considering there is no any noise.


texts:
I have a problem with SPI communication with ENC28J60 chip. Basically I can't use SSP in SPI mode as it is, because ENC28J60 expects CS to be low for multiple bytes while SSP shifts it high after each byte transmitted. To overcome this, I have GPIO bit acts as CS. Looking at logic analyzer signal, it seems correct to me, but still I don't get the expected result.

I have connected LPC1788 <-> ENC28J60 like this:

SSP0_SCK  - SCK
SSP0_SSEL - NC
P0_19     - CS
SSP0_MISO - SDO
SSP0_MOSI - SDI
GND       - GND

Signal looks like this:

MOSI looks correct, clock is somehow strange (I'm not sure if this 0.5 us delay is normal), enable is also correct, but MISO should return something on last MOSI byte (0x00).

EDIT: I have changed the clock to be compliant with ENC28J60 (clock low at idle). Picture is updated as well.


texts: Water level detection using non contact sonic sensors

texts:
I have been working on a project, where I need to find the water level of underground borewells with a diameter of around 6-10 inches and a depth of up to 100 meters. I have been researching a lot about the methods that I can use for this and after ruling out the contact method of a using a probe I settled for a non contact sonic method where a sound wave would be sent and the time of flight of echo would be used to calculate the distance. Now I was thinking about making a circuit out for it and had a couple of questions in mind:-

Which sonic transmitter can I use i.e. a piezo or a simple loudspeaker version?
What circuitry would be exactly required to work this out? As far as I know I would produce a PWM of varying frequency until I get an optimum value, fed from a controller and amplify it to feed it to the transmitter.
For the receiving sensor I think the condenser mic would serve the purpose, correct me if I am wrong and any suggestions would be appreciated.
Where can I find these sensors in order to use them for my project? My local vendors seem to be unaware about any of these.

Here is the link to the discussion a started for knowing about the frequency and spreding angle concepts related to sonic beams.

https://physics.stackexchange.com/questions/408894/sound-ultrasonic-waves-distance-travelled-and-spreading-angle


texts:
I am not very experienced with soldering. I have a basic soldering iron with a new tip, and a third hand.

Last time I tried soldering wires to a ble chip that looked like this, I ruined two chips in the process and gave up. Those were not cheap.

Now I want to solder this QFN chip but I want to have the right tools and skills for the job.

Perhaps I don't even need to solder, all I want is to connect some of the pins of the chip to a bread board. If there is another way to do that without soldering, I would prefer that.

I am a novice in this area. Any help, guidelines or reference to tutorials for beginners would be much appreciated.

I just want to know what is the best way, that is relatively safe (so I won't destroy the chip), to get it on a bread board.

Thanks!


texts: Connecting two USB 2.0 devices to a single USB port on an MCU

texts: I'm designing a PCB where I need to have two possible USB 2.0 connectors (and hence 2 sets of diff pairs) connect to a single USB 2.0 port on an MCU. Only a single connector would be used at any given time. What can I do to improve the signal quality? I've heard of redrivers/retimers but can these be used in this scenario to get around the effects of reflections due to the stub I would be introducing? If so, how many would I need and where would I add them?


texts: Adding a Vacuum Tube library to OrCAD CAPTURE

texts:
Introduction

I wanted to mess with Vacuum Tubes and learn from old electronics to show my granpa how they worked, specially radio (AM and FM). I downloaded a library of vacuum tubes but could not install it properly or i am missing something.

I am using OrCAD Capture 16.6-2015 Lite

How did i get to the problem?

I downloaded the RAR file containing a .lib and .OLB which i copy pasted into the next directories.

.lib at C:\OrCAD\OrCAD_16.6_Lite\tools\pspice\library

and

.OLB at C:\OrCAD\OrCAD_16.6_Lite\tools\capture\library

Where is the problem?

When i run the simulation it jumps into this error:

ERROR(ORPSIM-15108): Subcircuit 12AT7 used by X_VL1 is undefined

That means it can not reach the library or some other file? I have read another question about the same problem but still could not solve the thing.

Extra

Here is a pic of the schematic if someone is interested of the FM radio with vacuum tubes.

PD: I know the values are not correct or adequate, it was a test to see if it could simulate and i am open to improvements if it a simple change i can understand.


texts:
I have a sabertooth motor controller and it is rated max 33v input. I need (at max) almost double that on the output. Can I hook up one of these to the output port, between the sabertooth and the motor and get up to 60 volts?

If so, What happens if the input voltage is less than 10 (it says that's the minimum)

All my amps are in range. Motor draws 5 amps max, and sabertooth can handle up to 25A. Power supply can handle up to 30A.


texts:
I'm really confused understanding the following device manual:https://www.endevco.com/product/prodpdf/136.pdf I don't understand most of what they write. Any one has some idea about these terminology?

1) Input impedance: 1 Meg Ohm minimum. Is that the built-in input impedance of the amplifier?
If it is why doesn't it just say 1 Meg Ohm? Why does it say "minimum"?

2) What does "Common Mode" mean in this context?
Isn't' it supposed to be very small for amplifiers? It says 50 Volt. Why do I have to know that?

3) Common Mode Rejection: It says 200 ohm imbalance, DC to 60 kHz. I don't understand what they mean.

4) Input imbalance adjustment: Whats that about? Do I supposed to deal with it?

5) Linear output: What is the difference between linear output and output?

6) Corner frequency? Is that a kind of limitation?

7) Cross talk between channels? 80 db RTI. What does it mean?

8 ) Resolution? Do they mean the amplification factor for the signal input?


texts: Are there DC motors that can apply constant torque under extended stalled or reversed conditions?

texts:
I need to be able to generate constant torque and my first approach is using a DC motor. But, the problem is that I'll need to be able to apply this force in a stalled (static) state or even a reverse state where there is counter rotational torque which is greater than the motor torque being applied to the motor so it is turning against its own torque but just resisting the external torque.

I know that most DC motors would be prone to overheating in this condition. Is there a better option?


texts: Does a "Buck Step Down Voltage Regulator" provide constant output voltage regardless of input voltage?

texts:
I've got a small solar cell panel rated at 20V on a good sunny day. I need to regulate this down to 13.8V to charge a lead battery.

Can I use a "Buck Step Down Voltage Regulator" for this? I'm uncertain about whether the regulator will provide 13.8V regardless of input voltage, or if it just provides an output voltage relative to the input voltage.

Specifically, I'm looking at an LM2596 regulator.


texts: Continuous duty tolerance for automotive resistors

texts: What is the designation for resistors to be used in 12 v automotive applications?  The resistor would pass 5-10 V continuous while the vehicle is switched on. The goal is to lower the standardized switching temperature range for automotive coolant controls. I think this is a watt question.


texts: Question about a high voltage setup/scenario

texts:
I was wondering what would occur in the following setup.  Say you have an circuit basically like this:
V1 is a source of high voltage (high enough for corona discharge to occur), and no current can flow through the source.  The resistor has a high enough resistance that most of the current from the source leaves as corona discharge through the open wires.  The capacitor is initially charged to the same voltage as V1, and no corona discharge or leakage can occur from the capacitor, so it can only discharge by arcing across the small air gap and then through R1.  What I was wondering is does/can the corona discharging electricity from V1 prevent the capacitor from discharging?


texts: I need to detect zero crossing for a soft starter. A long while ago, I have done it using a 1 Mega ohm resistor directly connected to micro controller at one side and live power at another side. I was successful but is it advisable ? what other way I can do it cheaply and reliably ?


texts: Applied 370degC at the input of an ADC in a Microcontroller

texts:
I am using this Microcontroller - 100 pin

I have configured pin 82 as an ADC input. ADC Reference voltage is 5V (provided from an LDO whose input voltage is 12V)

To test my ADC accuracy, I took a thin 45cm copper wire from that pin and started to measure.

But while the board was in functioning, by mistake I used the soldering iron at the other end of the wire taken from the ADC pin. The soldering iron was around 370degC for 3sec contact at the wire.

Noticing this immediately, I turned off the module power and restarted it again. Upon restarting, the power module started consuming an excess current of 80mA.

What would have happened at the ADC input pin due to this mistake?
And what would the same scenario if those pins were output (open drain or push pull)?


texts: Altium re-synchronize schematic and PCB files

texts:
just transfered from Eagle to Altium here. So I got 8 schematic files and the respective PCB file in one folder (all Altium format). I imported them in one project but still can't edit them synchronously.
I tried to re-annotate as said in:http://www.carminenoviello.com/2016/08/28/correct-perform-re-annotation-designators-altium/

There is still no link between them. Please help, many thanks.


texts:
I would like to know how to calculate or select DC motor parameters when knows some parameters.

Knowing parameters:

Speed range: -2000 to 2000 rpm
Torque range: -65 to 80 Nm
Expected friction torque: 2 Nm max
Total moment of inertia of the load: 0.8 kgm2 or less

How to calculate or select following parameters?

Va- armature voltage
Ra - armature resistance
La - armature inductance
K - motor constant


texts: How to view pre-trigger data on digital scope (Owon SDS-7102)

texts:
Noob oscilloscope user here.

I want to view the voltage rise on my oscilloscope when I connect a device to a 1.5VDC power source, to see how clean the connection is - i.e. how many times the voltage bounces on/off/brownout/etc before stabilizing.

I set the scope trigger to about 200mV, and the input to DC coupling.  Measure depth is set to 10M samples at 10MS/sec sample rate.  Trigger: single, rising edge.  Holdoff is set to minimum value possible (100ns). There is no option to disable holdoff that I can see.

The scope triggers and captures the signal, but there is no rise.  It is immediately captured at 1.5V with no rising edge.

I assume since the voltage stays above the trigger level after the initial rising edge, it continues sampling until reaching the end of sample memory, which is 10M samples at 10Ms/sec = 1 sec.  So I'm seeing a 1-second-long 1.5v flat DC.

Is there a way to define the length of pre-trigger data to capture?  Also I'm confused as to why I don't see a rising edge, since the trigger level is set to only 200mV.

Thanks for any suggestions or explanations.

Here's a screenshot:


texts: Consistent LED intensity from low and variable voltage supply

texts:
I want to light 1 red LED among 3 (or no LED at all; never 2 or 3 simultaneously), using 3 output ports of a micro-controller (PIC18LFxxx or so). The catch is that I'm operating from a low and variable voltage supply Vcc_IN of 2.2V to 3.1V, and want to avoid too much variation in the LED current (I'm content with like 2mA, give or take 25%). This simple solution won't cut it:

simulate this circuit – Schematic created using CircuitLab

Instead of R1, it looks like I need an ultra-low dropout 2mA current source.
Also my application requires a low current consumption, especially when Vcc_IN is minimum (2.2V), for then I have barely enough current available for 2mA in the LED. What reliable, easily sourced, cheap, simple solution is there?

Clarification: A key issue is the very low voltage margin between the red LED's forward voltage @2mA (say about 1.7V) and the minimum Vcc_IN voltage (2.2V); these mere 0.5V must be enough for the dropout voltage in the Mx transistor (say about 0.2V) and the current source. Notice that if I adjusted resistor R1 experimentally to get an appropriate current at the low range of the supply voltage, the LED current would increase dramatically with power supply voltage.

I thought I had found a solution using one of the output of a MAX1916 (and reversing the polarity of the CPU output ports). The current regulator section of that IC (featuring a MosFET current mirror with x230 gain) would be quite nice for my use, unfortunately it seems that I do not have enough voltage to force the IC in ON mode.


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A Unijunction Transistor has a negative resistance region where voltage drops with an increase in current. This was explained to me as a situation where "Ohm's Law is broken". This doesn't sit well with me.

Can anyone explain how this negative resistance and inverse voltage-current relationship works in terms of Ohm's law?


texts:
The Question:

When is using latches better than flip-flops in an FPGA that supports both?

Background:

It is a well-known principle that level-sensitive transparent latches should be avoided in FPGAs, and edge-sensitive flip-flops should be used exclusively. Most FPGA architectures natively support both latches and flip-flops.

The general advice -- even from the FPGA vendors -- is to watch out for latches, or never use latches, etc. There are very good reasons for this advice, the details of which is all well-known. However, most advice is phrased, "don't use latches unless you know you need them".

I am an experienced FPGA designer, and over the years every time I thought I knew that I needed a latch, a quickly realized that there was a better way to do it with flip-flops. I am interested in hearing examples of when using latches is unequivocally better.

Important Note:

Latches vs. flip-flops often gets people riled up. I am only interested in the answer to the question. Responses explaining the difference between latches and flip-flops, expounding reasons to use NOT use latches, detailing why flip-flops are better than latches, talking about how latches are better in non-FPGA targets, etc, would be totally off-topic.


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I've been reading a lot, here as well, and from what I understand, your garden variety battery meter isn't truly accurate for telling you the voltage of a common household use battery at any given time (AA, AAA, C, D, 9V, and button cell). This is due to no load being placed on the meter while you test a battery. The load, if I've read correctly, gives you a more accurate understanding of what a battery can do in an actual real-world application.

So, I'm trying to buy a device that cheaply tells me what any battery I have is able to output but I don't want to buy something that only gives me a superficial inaccurate reading. Does the device I want exist or is it something I'll have to assemble out of different components like a resistor, etc?

Thank you for any help and for anything I can get from you to learn this better! You'll have to go easy on electronics fundamentals if you're going to explain concepts to me. :)


texts: Connecting BLE module to Lipo battery and recharge it?

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I would like to use a BLE module, where I can solder a tactile switch. There should be also the option to charge the module via USB. Earlier I have only worked with breakout boards, where I could connect the battery to the GND and VCC pin. Now I would like to use the BLE module directly to reduce the size of the device.

I have worked with the NRF51822 before which should meet my requirements. Unfortunately I am really new to schematics and struggling with the information provided by it. I also wondered about the naming of the pins. Is there a convention and official list where I can find more information? Could you explain me how I can find out what the different notation stands for? Is there a general legend?

The schematic of the board for the 51822 is listed here. Do you have any good literature for the wording and understanding of these schemes? Can I simply connect the battery to VDD and DCC? Doing a Google search for "VDD" is not that helpful.

I would use it with a Lipo charger like this. Would you recommend such a charger or what is the most elegant way?


texts: What are the chain reaction that create the electromagnetic wave?

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From my very limited knowledge I know that an electromagnetic wave is created by some chain reaction of accelarating/oscillating electric and magnetic waves, I also know about how the electromagnetic wave looks like and have basic understanding about electric and magnetic fields how a magnetic field can be created from moving charge, etc.

One thing that I don't understand is how those waves interact with each other to create the chain reaction that drives the electromagnetic wave.

Can someone please explain how this happens?


texts: Heating up using an LM317 voltage regulator

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I try to regulate a 12V into 3.7V using an  LM317 voltage regultor.
I used R1=220Ohm and R2=470Ohm, using this circuit:

It regulates a 3.9V (close enough for me,) but it heats up. I can't even touch it while it is powering an ESP8266 ( which draws a max of 200mA.)
Why is it getting hot?


texts: What is this Op-Amp Configuration doing?

texts: This Op-Amp Arrangement is part of an analog signal processing for a knock sensor of a combustion engine and I'm very curious about what this part actually does, as my google research didn't help me at all.


texts: Assigning binary value to decimal value using counter


texts: Laptop style multi-cell battery charge and power draw

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Basically, I'm trying to build a laptop of sorts. Long story... but I want to be able to have the same type of battery setup. I need between 14 and 24V from a multi-cell lipo pack but I want it to act just like a laptop battery would. Plug in the power adapter and it powers the whole thing plus charges the batteries. Unplug it and it automatically switches to battery power.
I've seen a lot of battery management boards for charging multi-cell lipo packs (in series) but they all seem to be for charging the battery without any external load.
So how do I even do that? Preferably is there some sort of pre-existing board I can use for this?


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I have the following circuit:

Here I have obtained the equation of Ud = U * ((deltaR / R)/(4+2(deltaR/R))). But I'm stuck on the part on how to derive that formula.

Any help or guidance is appreciated. (mainly since my book don't have the answer to this question that is within it)


texts: Solar panel simulation for 7 solar cells in series

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I have this question about the circuit that I am working on for quite long and it is just not working. Please help, i have already tried every thing i could understand.
I followed a YouTube tutorial and the circuit is working fine for the inputs entered in the video but not working for my modified inputs. i will attach the snapshots of Youtube tutorial below and my input values are mentioned here:
VOC=2.33V,
Short ckt current Isc=500mA=0.5A,
No.of cells in series = 7.
I want to obtain the maximum power curve for the given conditions. But I am getting power only in few mW that should not be like this... please suggest what changes should I make in circuit. The
subcircuit is of a single cell and  the main circuit is for series connected cells.
https://www.youtube.com/watch?v=Z2C28OXu4xA&t=617s
p.s. also if you can explain the purpose of .param IS=1nA . What does this current mean and why is it needed, why are there 2 current supplies, 1nA in main circuit and 5A in sub circuit?
here is the link of youtube tutorial, i followed.


texts: KiCAD symbol editor - how to use insert key to duplicate pins with every other number

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I'm trying to make this header row in KiCAD. If I place pin 1, and press the insert key, it gets duplicated nicely. The problem is, that pin becomes pin 2, then the next pin 3. I want pin 1,3,5,7,9 etc on left side, and 2,4,6,8,10 on right side. Up to pin 144!

I tried shift+ins, and ctrl+ins. No luck. Can this be done? What is your advice?


texts: How will the resistance of this Evaluation Module affect the measurements of the current produced by this photodiode?

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A little context: This is part of a bigger project about glowing algae, my job is to design a photodiode array to measure the amount of light the algae produce in response to movement.

I have a good idea of which photodiode I'm gonna use, the S2387-16R, and my plan is to connect them to the DDC1128 Evaluation Module. This thing is a beast, it can measure ridiculously small currents, in the order of femto-Amperes, so I don't need to use amplifiers.

What I'm trying to find out is what would be the maximum amount of light I could possibly detect. I know that:

$$
I_{max} = \frac{V_{bias}}{R_{Load}}
$$

And here is where I need help. How do I connect the photodiode to the Evaluation Module?.

To help explain my question, here is the equivalent circuit of a photodiode, I took it from here.

Everything but \$R_L\$ are internal variables of the photodiode.

Now, at first I thought that \$R_L\$ would be the internal resistance of the Evaluation Board, which I don't know and it's not in the Data Sheet but then I thought: "this is like an Ammeter right?, and those are made to have negligible resistances compared to what you are measuring, right?, so I can just ignore the internal resistance".

If that's the case, then I can put some resistance I know, like 1 kOhm, in one of the terminals of the photodiode, connect that to the Evaluation Module, then connect the other terminal to ground, and that's it.

But I'm not sure that's the case, and if I say to the team that we can ignore the internal resistance of the Evaluation Module and I'm gonna have to justify it and justify it well.

And if I have to consider its internal resistance, what do I do? What would you do?


texts: Electromagnetic Interference in Converter

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I have a question about this line of a power electronics book:
"Another significant drawback of the switched-mode operation (in converter topologies) is the EMI (Electromagnetic Interference) produced due to large di/dt and dv/dt caused by a switched-mode operation."

How can the derivation of the current and voltage affect the EMI production?


texts: Controller for HDMI to 30-pin display connector converter

texts: I need to design a circuit for HDMI to a 30-pin eDP adapter. Do I need to use some high-speed microcontroller that takes the signal from HDMI or forwards it to the eDP connector or is there some chip available which does the same. I tried to search on the internet for some open source project of the same sort but I could not find one. So, it would be great if someone points me in the right direction. Thanks.


texts: What can be the reason multi-meter shows continuity even though there is isolation?

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I'm dealing with a module where the block diagram is given as follows:

The datasheet can be found both at here and an alternative one here.

When I perform a continuity test with a multi-meter between I/O Common and the Power Common pins, there is continuity and the multi-meter shows 0 Ohm.

But it seems according to what the datasheet tells and so the block diagram there must be isolation between these pins. Can I be wrong making conclusions about isolation by using a multi-meter?


texts: How can I properly measure a MEMS rate gyroscope's zero mean bias drift and are my measurements coherent?

texts:
I have been looking into Madgwick filters and fusion algorithms and on the original paper as well as some websites mentionning the subject, it is stated "The gyroscope zero bias will drift over time, with temperature and with motion.".
With this explanation and since it is measured in rad.s^-2, I assume it means that the gyroscope's reading when it is immobile, its zero-offset or bias, would change over time.
I tried to measure it on one of my sensors, an MPU9250 (obsolete sensor but its just a test), and did notice a drift, although it is very, very tiny.
I can't compare my values to known ones since it is not stated on its product specification sheet.
I couldn't find a proper measurement method so I came up with my own.
I continually measure the sensor's output when immobile for a given period of time. Every ten seconds, or around 1200 individual readings, I average the results in a single datapoint representing the current bias and continue to do so for the given period of time. I then calculate the linear tendency curve of the obtained dataset : the equation's slope should be the drift in rad.s^-2 since my averaged datapoints are measured in rad.s^-1 on an X axis measured in seconds.
I tried periods from 1H to 7H to try and see a change. My estimations are variating a lot (around 500% of difference between them on average so it's not very consistent) but their magnitudes are consistent. This drift seem very tiny to me to be correct : this a sample from the gyroscope's X-axis with 2273 averaged datapoints over around 7H (originally more but I cut off 5000s of data at the beginning since I was around the sensor and could have affected it).

The slope being -5.81E-08*x, the measured drift is around -0.0000000581 rad.s^2, -3,33e-6 °.s^-2 : that's a hourly drift of around -0.01°/s/h.
The Y and Z axes have a hourly drift of respectively +0.002°/s/h and +0.004°/s/h.
I couldn't find anything to compare them to. Are these values' magnitudes coherent with other sensors ? What would be a more consistent estimation method ?


texts:
I would like achieve a precise static RPM (+/-.1% error) on a small, low-cost permanent magnet brushed DC motor (e.g. Mabuchi FA-130).  The motor/gear assembly will be rotated at different orientations relative to gravity, but there will otherwise be no variable forces on the shaft/output.  From experimentation with a constant-voltage power supply applied to a similar motor, I measure +/-1% error (7750 +/-80 RPM) under static conditions.  Therefore, I believe closed-loop control will be necessary to achieve the desired precision.

In order to implement closed loop control at a low cost, I was planning on making an incremental optical encoder via a slotted disc and IR 'photointerrupter' (e.g. OPB610).  Assume the disc has 10 slots and is fitted on the motor shaft spinning at 6000 RPM, so 1k pulses/sec.  Also assume I am using a modern 16+ MHz microcontroller which controls the motor via PWM.

1) What specs/equations should I consider when determining what the resulting motor control precision will be?  How to determine the delay in updating the motor speed, as well as the resolution of speed control?

2) Is there a 'better' (and still low-cost) way to achieve closed-loop feedback than the optical encoder method described (e.g. magnetic encoder)?


texts: Basic Question : RC circuit why Vc node vary like this ?

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Follow are two figures. The first one is basic AZ circuit and autozeroed signal, which is a simple RC circuit with a switch. The second figure is about the voltage shows in the first one.

Operation Principle: phase 1 is to control the switch on/off. Each time switch S is closed, the output voltage Vaz is reset to zero and the noise source voltage Vn appears across resistor R and capacitor C. Assuming RC << Taz, at the end of sampling phase ( when switch S opens ) the noise voltage Vn is sampled onto capacitor C. The output voltage becomes equal to the difference between the instantaneous voltage Vn and the voltage Vc stored on capacitor C.

Question : I do not understand when the input Vn is varying like sinusoidal signal with a DC average, the Vc node is varying like the shown in Figure. 1) When switch is on, the Vc is suddenly according with the level of Vn, I mean, why it is like this ? why the capacitor should not charge/discharge after comparing the Vc is lower/higher than the input voltage ?  2) Even for so, during the switch is on, why the capacitor is exactly varying like the input signal ? The resistance why dont get any voltage distribution ?

Above are my questions, I think it maybe simple or I just miss some clear point here. This circuit and description is coming from a paper attached below, and its figure 2 on second page. The description of the circuit is on third page left down. Welcome any suggestions for my confuse. Thanks for the help.

http://www.bioee.ee.columbia.edu/courses/upload/Bibliography/enz_procieee_1996.pdf


texts:
When connecting a 10S LiPo (42V) to my ADC via a voltage divider, I began wondering how to calculate the output impedance of the divider.

simulate this circuit – Schematic created using CircuitLab

For example, what is the output impedance of the above circuit?

(The ADC's specs recommend a signal impedance of 10kOhm or less, which I simply translated to 0.5mA @ Vcc=5V (worst case) and figured I'd be fine as long as the signal can source/sink more than 0.5mA. But that's not really 'calculating' the impedance...)


texts: How to control the output signal of this signal?

texts:
I 'm designing a sound system consisting of an audio source (say MP3) as an input to an amplifying circuit which will provide the output signal with a certain gain. This output signal will go through 3 speakers.

This is the amplifier circuit

What I need to know is : can those three speaker be connected to only one amplifier circuit or do I need a circuit for each one ?

What are the elements in the circuit do I need to manipulate in order to control the output signal in terms of increasing and decreasing the volume of one speaker and without affecting the other 2 speakers ?

note : speakers are 8 ohms and 0.25 watt each just for testing ... larger speakers will be used eventually.


texts: Two flyback diodes in parallel across a relay coil?

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I'm using relays that contain a flyback diode internally, so no need to add an external flyback diode. However, I want to provide a place on my PCB to possibly stuff a flyback diode in case I would have to replace the relay with a version that does not have the internal flyback diode.

But I was wondering: suppose the relay has a flyback diode built-in and I still do stuff the external flyback diode so the flyback diodes are put in parallel. Will that do any harm?


texts: which one is better for smoothing a sine wave: Low pass filters or a serially connected inductor?

texts:
Smoothing a sine wave is my main concern in this question. I have a sine wave made by DDS that in higher frequencies shows some steps. Normally in every electronic class it is heard that the best solution is a low pass filter but low pass filters have a big drawback: amplitude reduction.

On the other hand by putting an inductor along with the signal we can obtain even a better result but I have not seen this solution in any books or nobody talks about that (At least those teachers I had!). Is there any problem with this method?


texts: Switching logic for 2.5 bit pipeline ADC

texts:
Below we have 2.5 pipeline section, with the Vout Vin diagram.
In the diagram we see 6 transitions.
But in the circuit we see 3 MUX'es with 3 wires each going inside so there are 9 transitions.
I can't see how it's 6 transitions as shown in the Vout Vin plot?


texts: 10Ω series resistor in output of headphones amplifier

texts:
I managed to reverse engineer a headphone amplifier in a USB DAC that I bought on aliexpress. As I expected there is a electrolytic capacitor in series to the output, but there is also a 10Ω resistor in  series. What is purpose of this resistor? I would like to short it to increase damping factor (see NOTE1), but I'm sure there is a reason to put it there.
DAC is "called": SPDIF Interface USB decoder ES9028Q2M + AD823 + SA9023 ES9038 DAC computer Sound Card headphone amplifier not need power supply
NOTE1: Headphones have unwanted own resonances. Removing the series resistor decreases their effect to the sound assuming the headphones are passive.


texts: What is the purpose of diodes in flip-dot displays?

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In most flip-dot displays i've seen, the electromagnets have a set of two diodes connected to them. This is also mentioned by David, who asked a question about the displays before.

However, in the answers no one seemed to be sure why the diodes are put into the circuit.

simulate this circuit – Schematic created using CircuitLab

As shown in the schematic, each row has two diodes connected, one row has all anodes in common (Row nL) and the other row all the cathodes (Row nH).

Does anyone know why these diodes are put in the circuit as shown?

Possibly it has something to do with the "freewheeling" path, when the column or row voltage is switched off.
Another idea is that by the addition of the diodes, the display can be changed per row/column instead of flipping each pixel individually. I can think of a circuit to flip a complete row at once, but usually the displays switch in a horizontal manner (the pixels flip starting from the left and moving to the right), and I don't see a way of making a simple circuit to switch the display per complete column.


texts: Is using diodes in this scenario a common good practice?

texts:
I will purchase two rechargeable 12V 50Ah batteries. The batteries will be same model same type and will be fresh. There is a non-technical reason for not using a single 12V 100Ah thats why this question is related to connecting two batteries in parallel.

I have read that even the batteries are same type and both are fully charged, their inner resistance ect might differ and I have encountered an example which uses two diodes as shown below:

So imagine at the beginning the batteries are fresh and fully charged. But by the time one might differ than the other. Besides after they are discharged and if a person charges them again. There might be risk because the batteries might not be charged exactly same.

My questions are:

1-) Is this way of connecting batteries with diodes common and good in practice?

2-) Which parameter from the data-sheet of a Schottky diode should I consider if the nominal current drawn will be 1A?


texts: Why does a Peltier cooler heat up when cooled by ice?

texts:
On this post, the question presents a problem of a Peltier cooler heating up after operating for a while. The explanation was that the Peltier cooler is only able to maintain a fixed temperature difference between the cold side and the hot side. Because of this, as heat is taken from the cold side and deposited onto the hot side, the temperature of the hot side begins to rise. Because the cooler is only able to sustain a fixed difference between the sides, if the temperature of the hot side begins to rise so does the temperature of the cold side. So in order to cool the cool side, the hot side's heat needs to be dissipated.

That's my convoluted reinterpretation, but I think I got the idea. Ultimately, I need a way to expel the heat generated by the Peltier cooler. I've seen many people invest in large heatsinks with multiple fans, but I'm kinda low on money:P I was wondering if ice would work well. The heat generated would be, just as in a heatsink, sucked out from the hot side of the cooler. So after some preparation, I took my device and slapped the hot side onto a slab of ice. Unfortunately, the same issue rose: the temperature dropped to the point where little flecks of snow began to precipitate on the cool plate; however, it soon started to heat up, melting the snow and, along with it, my hope. I don't understand, wouldn't the heatsinks used in this application be at higher temperatures than the ice? How come people using heatsinks are reaching lower temperatures instead of when the device is cooled by ice? Furthermore, if the heatsinks are at higher temperatures than the ice, then this doesn't align with the temperature differential spec of the Peltier cooler, which I guess means the unit could be defective. But I have a feeling my understanding of how these units work is wrong. Any help would be appreciated:)


texts: Scripting to automate projects with microchip tools

texts:
IDE: MPLAB IDE 8.87
Compilers: C30/ASM30
Debugger/Programmer: MPLAB ICD 3
Windows 7

Question: I have utility projects such as clearing an EEPROM on custom hardware, retrieve data from an IC, and so on. I would like to be able to automate the procedure for such tasks.

Example: Clear EEPROM.

Input to script: Start location, number of bytes, EEPROM physical Address
Output from script: Selected range deleted successfully/Failed

The steps for this will be to build and link project with the input information, program the uController connected to the debugger, execute code, validate for successful completion and inform the user of the outcome.

How can I write scripts like this?

I have no experience of previous scripting, and this question is motivated simply to avoid wasting time in the future.

Kind Regards,


texts: OpAmp resistor to ground in feedback loop

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I am currently tasked with improving the design of an electrometer unit. It was NOT designed by an electrical, and there are some questionable design practices. My question is concerning the first amplification stage. A much simplified schematic follows:

In this schematic, R1 and C1 are set from a network of relays (not shown). R2 is constant, and in all cases much much less than R1. My question is, what is the purpose of R2? I have never seen this type of feedback loop. It seems to me that this is just going to make the opamp have to work a lot harder to maintain stability. I'm tempted to just remove R2 outright.


texts: Using Python to control Brooks MFC Power Supply

texts:
Is it possible to use Python to control the Brooks 0152/0154 power supply that powers and controls Brooks MFC units?

The manual mentions the pin outs of the RS-232 ports, but nothing about how we can control the Brooks 0152/0154 through the RS-232 port.


texts:
I'm a software engineer. As a programmer, I have an understanding of what my compiler does for me because I've manually written a close textual representation of what it outputs (e.g. assembly). For precise details of what's output I can look at the ELF/COFF/MachO specifications (e.g. the file type that it translates my code into, results may vary by language). To figure out what the encodings of instructions are I can look at look my processor's instruction manual. That gives me enough information to understand the kind of data the compiler is outputting. It also gives me the vocabulary to ask questions like "How do I inspect details of an ELF file" and that question is relatively well-formed. I could also ask "How do I look at the assembly generated by my compiler" and that question would be well-formed. Eventually the bytes specified by the ELF file get put into memory, and the processor runs each instruction in order and I understand the semantics of each instruction.

The equivalent steps/questions are entirely unclear to me for an FPGA. I don't know what Verilog or VHDL get translated to. I don't know what the underlying primitives the FPGA operates with are. I don't know how to ask questions like the two well-formed questions above because I just lack the words to ask. It might be the case that equivalent questions make no sense in this context but I have no way to know that at this moment. All I know is that I can write some Verilog and then it winds up being run on a simulator or on an FPGA.

I write some Verilog which is then synthesized to...something? What is that something? Is it a file that I can inspect? Is there a standard format used that I can look up? For instance if I wanted to write a simulator myself, what format would my simulator consume?

After that, the synthesized output is programmed onto an FPGA. What primitives does that FPGA use? If this was an embedded device then generally bytes would be written raw to flash or some kind of storage. Is there an equivalent for FPGAs? Maybe a more abstract and more answerable question would be "what bytes go over the write when an FPGA is being programmed?"


texts: How can I prevent a 556 timer IC from becoming very hot?

texts:
I built the circuit described in a previous question/answer which I will repost here:

It's been running quite well, actuating the solenoid at regular intervals as designed. The TIP122 transistor is barely warm, the solenoid is within normal temperature for its duty cycle, but the 556 timer IC is too hot to touch. It's been operating continuously for 24+ hours without any failures, but I am concerned because I think that this IC should not be warm at all.

Is there something I overlooked in this schematic that should be done to prevent excess heat in the IC? I haven't (yet) measured current usage by the IC alone, but the total circuit draw is 125 mA on standby and 2A when the solenoid is actuated.


texts: Right ground connection between different blocks

texts:
Which is the right way of ground connection?

Is it necessary to separately connect grounds between different blocks, without touching other grounds? Something like ground PCB trace going through another ground polygon?

What about servo cable connection to the ESC? Signal and ground? Or signal alone?


texts:
First of all, is there a name for thse kind of converters for easy searching?

There are some voltage adjustable DC to +-5-24V DC converters on eBay but they can't handle more than few hundred milliAmps.
I need a +12V 1A output and -12V 0.5A output from a single 12V or 19V source.

Are there similar bipolar DC converters but for slightly higher currents or do they have to be made from several readily available components or even custom circuits?


texts: Building a simple manual Intel 8085 study kit

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I am toying with the idea of building an Intel 8085 demonstration/study kit which would consist of an Intel 8085 microprocessor on a PCB, where all input nodes (including the clock X1, X2) would be connected to switches and the output nodes would be connected to LEDs. The user would then manually simulate the memory step-by-step by using the switches and storing the data on paper.

My question is whether this would be feasible. In particular, can the 8085 handle a "clock" signal that is activated by hand, i.e. very very low and irregular frequency? Moreover for the bidirectional bus, what would be a good design to keep the read and write modes? And is there anything that I should be especially aware of, or that may easily go wrong?


texts: Are there standardized values for the turn ratio of transformers?

texts:
I am simulating a dc battery charger. The circuit contains a step down transformer

I will need to lower the tension from 311 V (Vp) (or 220 RMS) to 15 V (Vp). One possible option for the turn ratio would be nprimary=311, nsecondary=15. But I highly doubt I could find practical transformers with this turn ratio. So is there any table/reference where I can find standard (or at least common) values of transformers turn ratios?


texts:
I read somewhere that keeping a solenoid activated is bad for it (overheating or something). Is this the case, assuming that the power supplied to the solenoid is of the correct voltage, or is it OK to keep a solenoid powered for long periods of time?

EDIT: Just to add to this, it seems that one contributor to solenoid burnout is the inrush vs holding current. Some solenoids are apparently "continuous duty" vs "intermittent duty" (http://www.thefreelibrary.com/Solving+solenoid+burnout.-a011845237). The one I am interested in specifically is this: http://www.amazon.com/0837L-Open-Frame-Solenoid-Electric/dp/B00AOCAETQ/ref=sr_1_1?ie=UTF8&qid=1461097053&sr=8-1&keywords=lock+type+solenoid


texts: Is there an error in the datasheet for the SN74LS169B?

texts:
I was looking at the TI SN74LS169B, a synchronous up/down binary counter.
Product page: https://www.ti.com/product/SN74LS169B
Datasheet: https://www.ti.com/lit/gpn/sn74ls169b
According to the datasheet:

The direction of the count is determined by the level of the up/down input. When the input is high, the counter counts up; when low, it counts down.

However, I have been examining the functional logic diagram provided in the datasheet, and it seems to me that the behaviour should be the opposite. This is the functional logic diagram from the datasheet:

Assuming that Q is low for all the flip flops (the counter is at 0), LOAD is high to disable loading, ENP and ENT are low to enable counting, and U/D is high to set the counting direction to UP, I get the following result:

It looks like the inputs to the flip flops are all high, indicating that the next state of the counter would be 15, rather than 1.
Repeating the calculations for when U/D is low to set the counting direction to DOWN, I get the following result:

Now, it looks like the next state of the counter would be 1, rather than 15.
I have double, triple, and quadruple checked my work... is the counting direction backwards from what the datasheet indicates, suggesting an error in either the description or the logic diagram, or am I missing something??


texts: What is the capacitance and/or inductance of a single straight piece of copper wire?   I know the answer is on Wiki, but I need for the answer to be supported.  I know that Wiki provides references, but I can not get to the references.  I am don't have access to the IEEE data base or any other such scholarly database or web site.  I actually need a scholarly paper or text book reference such as by J.D. Jackson.  I have been out of school for a long time (3 years) and I am still trying to finalize my thesis without having the needed reference resources.


texts: Design of low current sensor from 50mA to 2A in a dc-dc buck converter

texts:
I would like to sense the current from a path where a current of 50mA to 2 A is flowing to the load. Can I use simple differential amp with gain across the Rsense =20mohm or is there any contemporary design help.
Output of a dc-dc buck converter with Vin =21V , Vout =10V C =15uF etc, Load is 6 ohm. I would like to measure the current for some decision making , mode change etc
thanks


texts: Simplest way to short two leads with GPIO

texts:
I have a piece of hardware that has an open collector GPIO as shown below:

I'd like to have use the open-collector output to short two floating wires together -- they're essentially two leads from a button and I want to electronically control the button press.

What's the simplest and most reliable way to do this?  Relays seem way overkill when the current and voltage requirements are almost non-existent -- I just need to be able to selectively short two wires.

A FET solution seems reasonable, though honestly I'm not entirely sure how to go about it as there's no clear way to reference ground (both leads are essentially floating), and I don't know how I'd create the proper V_gs.

What other ideas and solutions could work?


texts: I am new to making PCB's and I have a question. I have an IC and I need to make pads for it on my board. ON many PCB's  I observed that the area where I place the pin has some metallic material on it so the pin sticks to it correctly. What layer is this. The place where I solder the resistor and capacitor(the leads is often metallic and silvery). IS this the cream layer. Or is it something else?


texts: How can i use my power supply ( 24VDC 5A ) in redundant mode ? I need to design it

texts:
In redundant mode, if one of my power supply goes off or faulty, my standby power supply shall overtake. I am thinking to use SPDT Relay (24VDC) both in Input as well as Output. secondary power supply will be connected to NC pin and the relay will trigger by the output of Power supply 1.
attached is the block diagram.
Is this a right way !
will i get the efficiency !
Kindly suggest a better way to do so.


texts: Output changes wildly with input voltage in photodiode circuit

texts:
I am currently analyzing a photodiode sensor input circuit (not designed by me, but schematics drawn from a commercial product). I am currently simulating the circuit on TINA TI. While experimenting with different input voltages, I noticed that the output waveform (output of second op-amp) changes a lot with the input voltage, while the output of first op-amp seems to be amplified more linearly.

Unfortunately my analog electronics knowledge is very limited, so I couldn't understand which concept of analog electronics is associated with this result. Phase response maybe? Or something more complicated?

Diagrams:

Circuit

50 mV pulse transient response

100 mV pulse transient response

Bode Plot


texts: Why do diode datasheets list a maximum forward current instead of power?

texts:
Diodes normally list a maximum forward current on their datasheet, for example, the 1N5408 datasheet states it has a maximum forward current of 3A:

But there's a big difference between say, 3A at 5V (15W), as opposed to 3A at 1000V (3000W).
So why are diode's specified in this way? Does it really mean that this diode would break if I put 5V@5A (25W) through it, but would be fine if I put 1kV@3A (3kW) through it?


texts: Power Supply Transformer with 3rd Wire on Primary

texts: I'm sitting here with a $600 espresso machine with its power transformer not working (no voltage coming out of secondary, with 110V feeding the primary).  I've been scouring the internet for a replacement, but the cheapest I've seen is $249.  I noticed on the primary side of the transformer, there are two terminals for live and neutral.  I checked the resistance on the terminals and got no readings.  But there is an extra wire coming out of the winding that goes to the casing between the 2 terminals, but not finished to be used.  I did get a reading on resistance when I check that point with the neutral side.  So my question is what is this 3rd winding point coming out of the primary side?  Can this point be used to give the transformer a second life?  If not, what is the closes specs I can get away with as a replacement.


texts: Brushless motor design with additional separation layer at the air gap

texts:
As a thought experiment, I was thinking about how to actuate an passive impeller inside a tube from outside, contactless. Imagine a tube equipped with an impeller inside it. The impeller is mounted in a passive way such that it can freeley rotate around the tube's axis.
That setup can be used to generate air or water flow for example but the impeller has to be actuated in order to do so.

What I was thinking about is to mount permanent magnets at the impeller's tips and surround the tube outside with a stator containing many electromagnets.

The interesting question here is how does such a setup behave knowing that additionally to an air gap (in the case we want air flow generation), we have now an additional layer of material separating the rotor and the stator (the tube's material).

Does the tube's material play a role? If yes, what are the properties of that material that have an effect (magnetic permeability? magnetic capacitance?, thickness?), I can imagine that it would behave differently when using PVC, Stainless Steel, Iron, Copper.

How does the performance compare to a normal brushless motor? Which affects the system's performance more: the increased distance between stator and rotor, or the additional material layer between them?

Do such actuation systems already exist? If yes how are they called?


texts:
\$V_{i}\$ is AC source and the diodes are real.
From my search I found that if the diodes were ideal no current would flow which means that the output voltage would always be zero but since they are real how can I express the output voltage?
I have to find \$V_{o}=f(V_{i})\$


texts: How else, other than using kirchoff's laws, can this circuit be analysed?

texts:
simulate this circuit – Schematic created using CircuitLab
Attaching simplified working to show I've worked it out already, however the answer didn't come easily and I'm struggling to improve on circuit analysis. Also, what textbooks are good for improving?


texts: Revision and component selection of MOSFET driver circuit

texts:
I'm developing a board to drive 5 LED strips with 1A maximum current. I need some help for design validation and component selection.
The circuit is the following (repeted 5 times). The PWM signals (5 kHz) come from a PCA9685 or directly from the MCU (I have not decided yet).
The MOSFET is a RFD14N05LSM and the driver IC is a MCP1416.

From MOSFET datasheet I calculated the following values. Are they correct? Should I consider some safety factor in the calculations?

Turn-on current Ig= Qg(5)/t(ON) = 25nC/60ns = 417mA. Qg(5) is the total gate charge at 5V Vgs and t(ON) is the turn-on time from datasheet. For t(on) should I consider the rise time from MCP1416 datasheet, figure 2-1?
Power dissipation Pds= rds(on)*Ids^2 = 0.1 Ohm * 1A^2 = 100mW. From this, considering a junction to case thermal resistance of 3.125 °C/W, the temperature of the junction should be just 0.3 °C above the ambient temperature.

Regarding the driver circuit:

Could the following selection values be right for TVS diode D1? Reverse stand-off voltage 5.3V, breakdown voltage 7V, clamping voltage 21V. Should I consider anithing else in the selection of the diode?
Should I place a resistor between driver IC and the gate? If yes, how can I determine the rigth value and the power dissipation?
If I don't put the resistor RG, where are eventually dissipated the voltage spikes? I mean, if a 10V peak comes from the driver, the TVS forces the gate to 7V, where are dissipate the other 3V?
Can I add anything else to this circuit to increase overall reliability?
The datasheet of the MCP1416, sec. 4.3 (Decoupling Capacitors), recommends putting a low ESR film capacitor for decoupling. Since checking the datasheets of different film capacitors I did not find any reference to the ESR, what can be considered as low ESR? Can I take any film cap?


texts:
In the datasheet for the ET1200 EtherCAT ASIC (page 94), I am told that I need to calculate a CRC of some of the 16-bit data in its EEPROM. The only description of this CRC is:

  Low byte [of word 7] contains remainder of division of word 0 to word 6 as unsigned number divided by the polynomial \$x^8+x^2+x+1\$ (initial value 0xFF).

For some reason, reading the Wikipedia page on Calculating a CRC makes my brain melt. Especially since the example code is written in a special language.

Can someone please just tell me what I need to add to what, and shift where and whatnot? In C preferably.


texts: Help identify this audio electrical connector

texts:
My acoustic guitar's "piezo pick-up" contains a really big audio jack with about 7mm borehole. It is basically a hollow screw, fixed on the guitar surface with a nut and washer. This is much different from a computer's tip-ring-sleeve jack and RCA jack.

Fig. 1 : From outside.

Breakout of an old connector.
Internet shows very little information about this jack and generally terms as "jack" or or "guitar jack" although there are other types of guitar pickup jacks.
Now my questions are:

Does this type of audio jack have any specific name or term?

What kind of plug/ "male" jack do I need to connect this guitar to a speaker or sound system or computer?

Is there a specific circuit symbol for this type of jack and plug?

What would be the pin-out and circuit diagram for using this connector (both "female" and "male" type?)

Is there a specific name for the hollow 'screw'-like fastener?


texts: Does the Raspberry Pi Camera V2.0 have digital processing in the sensor itself?

texts:
The PiCamera documentation (https://picamera.readthedocs.io/en/release-1.13/fov.html#sensor-modes) states that an embedded GPU is used for all sorts of digital processing, including digital gain, white balancing, demosaicing, etc. (See section 6.1.6. Background Processes).

Meanwhile, the documentation of Sony IMX219 (https://github.com/rellimmot/Sony-IMX219-Raspberry-Pi-V2-CMOS/blob/master/RASPBERRY%20PI%20CAMERA%20V2%20DATASHEET%20IMX219PQH5_7.0.0_Datasheet_XXX.PDF), the sensor used in PiCamera, states that there is digital processing within the sensor itself (see section, "On Chip Image Processing".
The sensor documentation also says that the sensor has a power consumption for digital processes. However, it is worth noting that there are only a few steps of processing happening here - namely, test pattern generation and black level adjustment, digital gain setting, defect correction, and pixel realignment - and, therefore, the on-chip processing is incomplete. Meanwhile, the entire digital processing pipeline, which has 12 steps of processing, tinkers with the images when they arrive at the GPU. These steps repeat the aforementioned "on-chip image processing" steps.

This is weird because the PiCamera documentation explicitly states that the data coming to GPU is RAW Bayer data, which is totally unprocessed and processed at the GPU (which has the ISP). So, has the PiCamera only based itself upon Sony IMX219? Is it so that only the analog core of Sony IMX219 has passed on to the PiCamera, and other ends have been transferred out of it?


texts: Does it exist: 360 degree ultrasonic receiver/beacon combo

texts:
Note: I posted this over on Robotics but the more I think about it, the more I realize this would be better asked here.

Basically, I want to detect an ultrasonic beacon in a radius around the robot. The beacon would have a separate ultrasonic emitter while the robot would have the spinning receiver.

Are there any existing ultrasonic sensors that would meet this use case or am I stuck hacking one together myself? I have tried searching Google, but I assume the keywords I am using aren't the industry standard ones.

Is ultrasonic even the best choice? I was hoping that the beacon would be kept in a pocket, so I figured optical sensors were out. However, the beacon could be attached outside of clothing.

Edit: I should add that both the beacon and the robot will be mobile, so stationary base station solutions are not what I am looking for.


texts: If supply amperage is higher than max. amperage, do I need a resistor?

texts:
This is a pretty basic question, as I'm still learning the fundamentals of electronics. I understand the analogy where amperage is compared to the quantity of water moving through a hose.

I have a 5V-2A power supply and I want to power my circuit. Each components' pins have different maximum currents (250mA for PIC, 180mA for the LCD, etc.).

Now if I'm following the above "water quantity" analogy, it should be OK for me to connect a component that draws max. 250mA because it draws from the 2A instead of the power source forcing the current into the pin. Now, I will have 1.75A of current left for the rest of my circuit.

Do I still have to put a resistor between the power supply and the VDD pin of a component? If yes, why?

(This question arised from when I learned that there should be an approx. 100 ohm resistor between the microcontroller's output pin and the LED. The LED's current rating was 25mA and the pins maximum output current was 25mA too and I didn't understand why we needed a resistor in between.)


texts:
I have build a solution that looks almost like this:
The wires that does the communication between the Micro Maestro and the two Jrk's and the RoboClaw are not included, so this is not a perfect drawing but maybe you get an impression on how this looks.

I power my Micro maestro from the battery, and then power my Arduino mega from the Micro Maestro (5V) and also my Jrk's are powered from my micro maestro (this is not shown in the image).

The communication is done by sending commands from Arduino using serial communication (pin 10 and 11 on the Arduino) with the micro maestro and the micro maestro sends commands to the 3 motor controllers (jrk's and RoboClaw). This works ok for some minutes.

When I run this system for a while (3-5 min) I get an error from the Micro Maestro saying

Serial Error 0x0001

At the same time one of my jrk's gets really hot (an IC called MC33926)

I am now wondering if there is a connection between the serial error and the very hot component or whether it is the serial communication between the Arduino and micro maestro is going wrong.


texts: What contacts do the numbers on this DPDT relay refer to?

texts:
I’m new to electronics, could someone please list the contacts that belong to each number. e.g. COM1, COM2, NO1 etc.

It’s a Taiss/JTX-2C, MK2P-I DPDT Power Relay with Plug-in Terminal Socket Base, DC 12V Coil, 8 Pin 2NO 2NC (Quality Assurance for 1 Years) DC 12V


texts: Why does this mobile phone battery have 4 terminals?

texts: Why do some mobile phone batteries have 4 terminals? I want to use a mobile phone battery for my project.


texts: Can you program a micro controller to be a uart to usb bridge?

texts: From what it seems like, uart and usb are just two different ways of digital communication so it seems like if you just program a micro controller to accept uart through a couple io pins and put out usb in a couple other pins you could make a uart to usb bridge without buying anything. Kind of like translating languages. Is that how it works? Am I missing something? I am using a pic16f84a.


texts:
I'm looking at using 12VDC or 24VDC LED light strips for over and under cabinet lighting.  These would be the LED strips you can buy in 100 foot lengths and cut to the desired length.  They have solder tabs for connecting power.

My questions are:

1)  Can I use a standard 120VAC to 12VDC or 24VDC wall transformer connected to the LED lights, and control the brightness of the LED lights using a 120VAC lighting dimmer wired to the receptacle?

2)  If so, would I have a wider range of control with a 24VDC transformer as compared to a 12VDC transformer?

I would make sure that the transformers are rated to carry the load.


texts:
The answer is 16, but can anyone please explain how? note m is u

I confused because, I dont know how to solve for Vx ?
I know that once I find Vth and then resolve the circuit closed and finding Isc I can find Rth by ohms law.


texts: 32 kHz crystal not operating as expected

texts:
I've been trying to figure this issue out for a couple days now, reading up on typical crystal operation / configuration, and I'm at a loss. I tried searching here but didn't encounter anything similar to my issue, so I'm sorry if I missed my solution somewhere.

I'm trying to run an RTC off of an external crystal using a PIC, but the crystal isn't oscillating when I expect it to, and is oscillating under other circumstances, and I can't make any sense of it. I'm not an EE though, so I'm probably just being super ignorant.

The crystal: LFXTAL016178. I'm fairly certain that because nothing is listed, it's a parallel resonant crystal. Its load capacitance is 6 pF, which I've found to be sort of uncommon? I'm not sure.

The PIC: PIC24FJ128GB204. I've connected the crystal as the datasheet suggests, but it doesn't provide much explicit help in selecting load capacitors, so I did some searching and found other resources online to help me there.

The setup: I saw from a couple sources that a good rule of thumb for load capacitors is \$C_L = \frac{C_1 × C_2}{C_1+C_2}\$, adding stray capacitance to \$C_1\$ and \$C_2\$ of between 2 and 5 pF. I picked what I thought was a middle value of 6pF for both capacitors, and I'm still not sure how bad that selection was.

Here is a picture of my schematic:

Layout:

Cases where it doesn't work:

As it is in the schematic, with 6pF load capacitors on both pins, it doesn't oscillate. Unless it oscillates every 10 minutes or something.
With the capacitors removed, it oscillates extremely slowly, maybe approximately 2.5 times slower than it should. I didn't measure this speed.
With extra 6pF capacitors soldered on top to make 12pF capacitors, it doesn't oscillate.
With 3 pF capacitors and a 10 MOhm resistor across the pins. (RTCC clock is erratic.)

Cases where it does work:

When I probe the SOSCI pin with an oscilloscope. In the first three cases above, as soon as I touched the probe to the SOSCI pin, it started up and gave me a nice clean sine wave. It didn't do this when I touched the SOSCO pin, OR when I used 3pF capacitors. I know it wasn't working beforehand because of some LEDs that are supposed to blink every second, which only blinked with the probe connected. (I don't know everything about oscilloscopes, I just know how to operate them. The probe says 6MHz/1MOhm/95pF, and the scope says 60 MHz/1 GS/s and 300V CAT II where the probe connects. It's a Tektronix TDS 2002 if that means anything to anyone.)
When I connect a 330 Ohm resistor between SOSCI and ground. It's one of two resistors I have on hand; the 10k looked like it made it operate at about half the right frequency.
With 3 pF capacitors, but at 14 kHz.

Here are some frequencies that I've measured:

(12 pF Caps) Frequency touching probe to SOSCI: 32.7674 kHz
(12 pF Caps) Frequency output by PIC with the 330-ohm pull-down on SOSCI: 32.764 kHz
(12 pF Caps) Frequency output by PIC using LPRC: 32.68 kHz
(3 pF Caps) Frequency output by PIC: 14.08 kHz

Basically, what I'd like to know is why it oscillates perfectly sometimes when I use a scope probe, and what the correct solution should be in order to make it work as I want it to.

EDIT: I've only just found this application note, where it says that I should have selected a 12.5 pF \$C_L\$ crystal for my microcontroller. However, any crystals on Mouser/Digikey with my desired minimum operating temperature (-55\$^{\circ}\$C) are out of stock. I'll be getting one that will suffice for now, but I think my questions still stand.

EDIT2: With a fancy new crystal (\$C_L\$=12.5 pF) and some standard 22 pF caps, it worked at 32.7676 kHz. What does this imply about what went wrong with the old crystal (\$C_L\$=6 pF)?


texts: Simple-Coil-less-AM-receiver- how to make for 650kHz (BBC from Poland)

texts:
Can enyone help to make it for 650kHz (600-700kHz) for BBC reception from Poland ?
After making it does not receive any station.
What`s wrong ?
http://www.next.gr/inside-circuits/Simple-Coil-less-AM-receiver-l6022.html


texts: What happens if I don't tin my DIY self-etched PCB traces?

texts:
Once I etch my PCB from copper-clad FR4, do I need to tin the board with solder?
If I do not tin the traces, what are the possible issues besides greening over time?


texts:
I have made the below circuit using the MAX1771, but it does not work as intended. There is no increase in voltage at the output. It just outputs VIN minus diode drop at “CDI_TEST_HV”, as expected if it was turned off.

I have tried to eliminate R14 and tie it straight to ground. I have made a few scope images as well.

Can you please have a look at my circuit and see if there is anything obviously wrong?

This is measured at the gate of Q2.

This is measured at L2. Basically the same at both sides of the component.

More investigation shows the following measurements on the different pins:
1: 0.518 V
2: 12 - 23.9 V
3: 125 mV and reducing quickly
4: 3.4 mV
5: 1.503 V
6: 3.4 mV
7: 3.4 mV
8: 3.4 mV

It's interesting that sometimes it steps up to 24 V.


texts:
I followed a tutorial to get into pic microcontrollers.
But all code in tutorial supply me with errors.
For example if I use this code as a first line of my assembly file:
#include "p10f206.inc"
I get the following error:
'p10f206.inc' file not found


texts: 12 V 3.8 A water pump to 12 V 625CCA battery

texts: Wanting to use car battery to power pump. Pump says it's 12 V 3.8 A, uses a 8 A fuse. Trying to sort out possible solar input needed to run pump but the numbers don't make sense. What size solar panel would provide enough power?


texts: Compare tiny capacitance using comparator

texts:
I want to compare the capacitance of two tiny capacitors at around 10^-15 F each. One will change compared to the other by at maximum factor 3. I need to measure the relative difference between them to an accuracy of around 1%.
My idea is to connect them in series to form a ”voltage divider” and then connect the middle of them to a comparator which can then compare the voltage between the capacitors to some external reference voltage.

However, I have no experience with comparators or exactly how they work. Would the comparator try to draw a current from the capacitors it was comparing (and thus not work since there’s basically no charge to draw)?
What should I look for when buying a comparator for this application?

If this is simply not possible, how else might I accuratley (and cheaply) compare the values of these two capacirors?
Note, not looking for some expensive high tech solution here, looking for something which can be done at home by an amature.


texts: Single point vs Ground plane, in audio OP AMP PCB layouts

texts:
Recently I had posted a seemingly innocent question on another forum. I was trying to keep a small and relatively simple circuit down to a 2 layer board and was asking about the shielding merits of a copper pour tied to analog ground, as opposed to dedicating unbroken separate plane used for ground. Though my question was only in reference to the shielding value of such a copper pour, a major controversy started on an entirely different point. In my layout I had created a virtual ground using the typical voltage divider feeding a unity gain configured OP amp, and then had run every single analog ground return to a point adjacent to the output of that virtual ground. I had also done a copper pour on the least busy layer and tied it to that same analog ground, again at that same single point. But there soon ensued a series of posts lambasting my use of such a convoluted "spider web" scheme, with many chiming in that I should just create a ground plane and just make all connections to the nearest available point of that plane ( through  via when necessary). Well doing so certainly makes for a cleaner and simpler layout visually. But having gone the "single point" route for so many years, and having mostly successful (meaning quite and stable) designs, I'm hesitant to change. Especially as some of the arguments spoke of single point grounds as something archaic, and relegated to vacuum tube circuits. What?

So anyway, just poking around, my research on the subject seemed to show two camps on this subject. One argument is that when an unbroken ground plane is available, it is always superior. The other argument says that if its a high frequency circuit a ground plane is better, but for a low frequency circuit (including audio), the single point ground method is better, mostly to avoid ground loops.

Of course I still have a dilemma, as prototype costs are constraining me to a 2 layer board if possible this time, and this means that my pseudo ground plane will, at best, be a copper pour, broken by some short traces here and there. But before adding that complexity or possible exception to the rule, I'd like to put this specific question out for general discussion: For an audio design involving OP Amps, when is a Single point" ground scheme the bast way to go, and when is just the simpler "nearest path to a ground plane" the better (or at least an adequate) choice.

By way of example, these two layered screen shots show two reasonably similar versions of the same board, which in reality is about 4" x 2.5". In the first you can see lots of long traces on both sides of the board culminating at a single pad labeled AGND. The second is nearly the same circuit, but this time the blue copper poor area is part of the analog ground net, so all those long traces have gone away in favor of the nearest path to the ground plane/ copper pour. Aside from all possible critique about other layout issues one might see, this is just an example. I'd really like to confine this discussion to the original question.

single point ground version

Nearest path to ground plane version


texts: Measuring heart rate and hacking an exercise machine to extend the grip area

texts:
Most of you are probably familiar with exercise machines that have grips for each hand so that you can take your heart rate.

Imagine one for a skiing type of device...with the metal measuring grips on the 'poles' that you push/pull back and forth.

Do you think that we can retrofit it and replace the metal grips with a larger piece of metal that runs the most of the length of the ski pole without interfering with the measuring electronics?


texts: ENC28J60 Circuit Connected With 2 Magjack in Parallel

texts:
I'm using ethernet controller chip ENC28J60 and I need to have it connected to 2 magjack in parallel, but I'm unsure if I made a correct circuit, is this can work?
Please advise me, thank you very much..


texts:
I'm trying to design a purely resistive load that is digitally controlled. The idea is of an array of resistors that are driven with  power MOSFET's.
I want to feed a current pattern into the microcontroller and for the load array to follow it.

the following image gives an idea of what I'm trying to do:

It is a resistive array to provide different levels of current load. Every Resistor is switched on and OFF with a power MOSFET. The whole is going to be used to test a voltage regulator.
The applied Voltage is 5V and the current is up to 1 A.

To obtain a specific Current Value the corresponding Resistors has to be switched on.

As an Example to get a current of 600 mA , the resistances delivering 100 mA (R= 50Ohm) and 500 mA (R= 10Ohm) will be on, the rest will be off. I'm planning 16 resistors.
The switching between load steps has to be smooth and occur under 2µs. My concern is the transition process between two load steps.

Example : switch between step1 (R1= ON,R4=ON, rest OFF) and step 2 (R3=ON, R10=ON, R11=ON, rest OFF)

The state of the corresponding switching transistors is saved in a register and will be latched simultanaeously for all transistors. I'm using IRLML0040TRPbF (Datasheet)

The controlling microcontroller is an XMC1100.

I don't want to programm intermediary steps for the transition to be able to hold the timing criteria of 2µs.

I thought, as I don't have an inductive load, I don't need extra circuitry to assure the smootheness of the current step transistion.

am I right in that line of thought? will the current flowing in the resistors during the transition disturb the smootheness of the transistion significantly, even if I latch (from the µcontroller) simultaneously and the transistor is quite fast?

Do you guys have an idea how to proceed in that case?

I'm quite the beginner and would be grateful for any help.


texts:
Let's say the Vdsat = 0.2V for M1 to M4, but 0.5V for M5. VT is 0.5. I think it's:

ICMRmin = Vt2 + Vdsat4 = 0.5 + 0.2 = 0.7V
ICMRmax = VDD - Vdsat5 + Vt2 = 1.8 - 0.5 + 0.5 = 1.8V

The numbers don't make sense, so I'm pretty sure it's wrong. The goal is to get it between 0.4V to 1.4V, if that's even possible.


texts: Reverse polarity protection on model RC aircraft

texts:
I fly model aircraft as a hobby. On some model aircraft the battery connectors can be reversed especially the cheap JST ones with a broken or missing polarity locking tab. Or, the batteries can be mis-wired or a soldering mishap can lead to the poles being swapped. The classic solution to a problem like this would be a diode, probably a Schottky one.

But on a system where currents can exceed 100A, a diode is simply not practical; cooling and size constraints come to mind, as well as the wasted power being approximately 0.4 x I. If the power to an ESC is reversed, it may cause the body diode of the MOSFETs to conduct, leading to very high currents, immediately destroying the ESC. That sucks, of course. But it may be worse; if the ESC has a BEC output (a voltage regulator), the reversed polarity could break down the regulator and fry attached devices, such as servos, receivers, cameras and the like. Which would make for a really bad day.

Being an RC aircraft application, this needs to be reliable, crash-resistant (i.e. relays are probably not an option due to their mechanical nature), small in size, and low in cost.

So what solutions for this problem are there?


texts: Is it possible to design this circuit with a single potentiometer (L-pad)?

texts:
I'm designing an L-Pad for my speakers. They attenuate the signal while keeping a consistent effective impedance, which is necessary for the amplifier and crossover circuits.

Typically, these values are computed and hard soldered, giving one 'set' attenuation level.

I want to use a single potentiometer (though it could be a dual-wiper pot) to make this adjustable, and include 0 dB (completely out of the circuit).

Would this be possible to design, without the use of a microcontroller and programmable potentiometers?

It needs to maintain a constant impedance, and I'm using them on 8 Ohm speakers.

Solving for my application:

R2 = Variable from (infinity) Ohms / disconnected

R1 = 8 - (R2 * 8) / (R2 + 8)

Help!


texts:
Near to my location we have IAF(Indian Air Force - Tambaram) training center is there, While hearing FM radio at a at frequency of 106.4MHZ I can hear the cockpit commands/voices daily   when these IAF flights cross by.
How come it is possible? Is it due to FM radio i am having? I cant hear the same interference in mobile FM.


texts: Why do I have more flash (STM32F103RCT6) than what my datasheet says?

texts:
I'm writing a firmware to a STM32F103RCT6 microcontroller that has a flash of 256KB according to the datasheet.

Because of a mistake of mine, I was writing some data at 0x0807F800 that according to the reference manual is the last page of a high density device. (The ref. manual make no distinction of different sizes of 'high density devices' on the memory layout)

The data that I wrote, was being read with no errors, so I did some tests and read/wrote 512KB of random data and compared the files and they matched!

I did some research I couldn't find similar experiences. Are those extra flash reliable? Is that some kind of industrial maneuver?