texts: Switching Piezo Buzzer with a Transistor

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I want to be able to switch a piezo buzzer with arduino without connecting it directly.

I have wired the following circuit I found on the internet:

The problem is that the voltage across the buzzer is very low (lower than 1v when I connect a voltmeter instead of the buzzer)

My guess is that I lack some basic understanding of how transistors operate. Maybe I chose the wrong transistor or I need to apply higher voltage between emitter and collector?


texts: NiMh or LiPo batteries for unattended charging/usage

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I'm in the planning stage of a summer project: A WiFi controlled robot for remotely monitoring a shore home. The robot will consist of a 4-wheel platform (4 motors, 1 A stall current each, 7 V), Raspberry Pi Model A + WiFi dongle, and Raspberry Pi camera module.

Since this robot will be operated while I'm not at the house, I need to be able to remotely recharge it. The plan is to implement something similar to the Roomba's drive-on charging base:

My issue is that I'm unsure which battery chemistry to choose.

LiPo has the benefit of being lighter, but since their nominal voltage is 3.7 V, I'd have to put two or three packs in series to be able to run my motors (which need 7 V, as I mentioned). But, I know this not recommended because then charging the batteries in series is complicated/unsafe.

NiMh seems attractive: wide range of voltage/current ratings, not as prone to fireballs, albeit heavier. My thinking is I could build a simple charging base that trickle charges the robot's NiMh battery. No fast charging is needed (the robot will spend most of its time on the charging base, when not in use anyway).

Summary of requirements: rechargeable battery for unattended charging/usage, somewhere in range of 8-12 V, several amp-hours capacity (4-6 Ah, maybe).

Is my evaluation of this correct - that NiMh seems the way to go? Or should I consider LiPo?


texts:
Can ESP8266 connect to Wi-Fi network that requires not only SSID and password but also username and password?

It's not about web captive portal. It's about a popup that appears in Windows when you connect to the network where you have to type in username and password.

I'm using Arduino IDE.


texts: fan speed regulation causes other loads flickkering

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I am using traic based dimmer circuit for regulating my ceiling fan. when the fan is regulated to low speed the other loads(incandescent,tube light,LED) in the room are flickering. when i increase the fan speed to certain level the flickering stops. i've tried using same circuit in my friend's home. Everything works fine(No flickering observed). I am observing this flickering at low speed let say value of 40% power

Used components:
Traic : BT137/BTA24
opto coupler : MOC3023

can any one please suggest me the solution .
thank you.


texts:
The goal is to control 18 devices by using rocker switches with LED. The total ampere can be up to 25A.

The PCB size is 150mm x 250mm. The configuration is FR-4 with 2 oz/ft^2 copper. The bottom layer is GND plane where the top layer is 12V plane.

What are used:

12v 350w power supply unit
Multiple 6P Barrier Terminal Blocks
18 PTC resettable fuses
18 12v-led-rocker switches

Is this setup safe for such current flow? Is there any potential hazard with this configuration? What can be done to improve the design?


texts: Analogue (or digital) signal integrity with multiple sources of noise

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tldr: Can I transmit an analog signal through a noisy environment without it being corrupted, or should I use a digital signal instead?

My requirement is to transmit a signal from a MA3 absolute magnetic encoder 75 feet in the sky to a DAQ module on the ground. This model comes with an analog or digital interface. I would prefer to use the analog, because it is easier to interface with a DAQ module.

With the analog interface, the sensor has 10 bit resolution, 2.6 kSample/s, 0-5V output. To keep linearity of the sensor data around the 0 and 5V boundaries the output load impedance should be greater than 4.7kohms and less than 100pF.

The digital interface uses PWM. It has 10 bits of resolution and has a frequency of approximately 1kHz. The RC oscillator for PWM is only within 10% of its rated pulse period, but this can be accounted for by calculating the ratio of tOn to tOff for each duty cycle. In order to interface this with a DAQ module I would have to use counting logic. I am not a fan of this approach because the counting approach seems error-prone, and it will require learning software for the DAQ. However, I will use it if the analog route is impossible.

For the shape of the signal, I expect it to constantly vibrate slightly from the sensor position changing slightly, but change overall very slowly since the shaft it is monitoring rotates at less than 1 RPM.

There are three complications to this.

the signal has to pass through a slip ring
the signal has to travel from a height of 75 feet to the ground - I have heard that long wires act as antennae for EMI and the height of the cable in the sky may affect this
the wire carrying the signal will be no more than a foot away from wires carrying 3 phases of up to 40V of wild AC

My first question is: based on all of these sources of interference, does the analog signal stand any chance of maintaining integrity when it reaches the DAQ module? I lack the experience with signals to be able to predict whether this is feasible or not.

If you think this is possible, do you have any recommendations for making it work? The only approach I know of is shielding the wire, and keeping it as far away from the power lines as possible.

Thanks for your help


texts: Formula for calculating the MMF and its harmonics of n-Phase PMSM with integral slot winding (slot per pole per phase =1 & 2)?

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Data\Prerequisites:
Integral slot winding full pitch winding
Slot per pole per phase = 1 and 2 (two different possibilities)
Number of phases : n = 3,4,5,6,7

Assume number of turns = N and current to be pure sinusoidal

Is there a general formula (i.e. formula applicable for n-phase machine\windings)?
If not, can anyone please provide me a specific formula?
Or provide me with relevant literature.

My target is to calculate the harmonics of winding factor and MMF generated due to integral slot windings with more than 3-phases.


texts: Reviewing my very first audio amplifier circuit

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I created my first audio amplifier circuit, which seems to work perfectly in Falstad Simulator.
I don't know if it would work if I were to actually build it, though.
Are there any improvements that could be made? Is there something I forgot to consider?
EDIT:
I have modified the circuit and settled on a version that I think I can finally expect to work. By the way, I am trying to make use out of my 19V 2.1A power supply and pair of 6Ω ?W huge speakers.
I don't know if anyone will still see this question again but I'll be thankful for any advice or criticism I receive.
EDIT YASS!:
I built it and it is a complete success!
As a simple quality test I played on it perfect sine waves of all audible frequencies at maximum volume, and the result are very loud perfect sine waves.
At maximum volume all frequencies above 200Hz play at a level of 100% while 60Hz plays at a level of 85% and the level quickly goes down as input frequency decreases.
I also did many other tests through the input looking for defects on the amplifier, and it is free of crossover distortion, DC on speakers, and unwanted noise.
Complete schematic:

simulate this circuit – Schematic created using CircuitLab


texts: What does floating source mean in this context?

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What makes the load in the below circuit floating?:

Does that mean the load does not have a ground shared with the circuit ground?


texts:
So the process is to decompose the three phase vectors into two components Alpha and Beta (Im following the procedure on Openelectrical):

And the decomposition is done as follows:

When I do it myself, for U_Beta I get
        U_beta = Ua.Cos(pi/2)-Ub.Cos(pi/6)+Uc.Cos(pi/6)

Basically I get the signs for the last two terms for U_beta reversed.

What am I doing wrong?


texts:
Draw the circuit diagram for DC and determine the component value. The transistor must be biased with :

This is my attempt to solve this

The picture bellow is the way I drew the DC circuit diagram

I would really appreciate if I could get some feedback regarding and some help on how to find R2


texts: Can I run my Nios II from program in SRAM or SDRAM, how?

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Is there a "standard" (Altera supported) method to run my Nios II from off chip memory like SRAM or SDRAM? Since the design is in prototype stages, it means that I am using JTAG for configuration and all the configuration bit stream and the compiled Nios II program, does not have to be copied into the configuration memory like EPCS, EPCQ or CFI flash device.

Since on-chip memory is very limited it is better to use off chip memory for the program. How do I get the program into off chip memory then? I know this will require something called boot loader, but is there an application note or example of this? I have not found clear instructions on this yet.

During development one will have to compile and load program into the Nios dozens of times. Therefore, if each time one has to load a boot loader FPGA design to load the Nios II program into the external memory and then load the Nios II design into the FPGA, this 2 step process seems cumbersome.


texts: Where is the Intel Common Redundant Power Supply (CRPS) Standard Specified?

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Intel server reference designs use the Intel Common Redundant Power Supply Standard (CRPS).  These documents include a brief over view of CRPS with information like the pin names and refer the reader to the CRPS specification document for more details.  I've googled for the mentioned CRPS specification document but haven't been able to find it.  CRPS compatible power supplies are offered by numerous manufactures so the info must be out there some place.

What document / standard / specification details the CRPS standard?


texts: In practice, does the order of a series RLC-shunt circuit matter?

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In simulation I'm finding that the image pictured below works well to optimize a complex impedance match.  I know that Z = ZL + ZC + R, so in theory the order shouldn't matter---but in practice, with physical components, does the order of the series RLC components work "better" in some situations?

For example: should DC components be nearer to the RF line, or vice-versa?
Other considerations?

(In this case the shunt side is a FET drain bias, so the capacitor must be there somewhere to prevent a DC short.)


texts:
I have a 24V battery bank and would like to discharge it in order to test the performance of different solar charge controllers. Eventually the batteries will supply a 2hp (1500W) DC motor and it is this that I would like to simulate.

Can I use a resistive load to approximate the current draw of the motor in lock conditions? How do i calculate this? A pot or a rheostat seems like the way to go but I am unsure of how to select one.

Following Ohm's law I expect the current draw from the motor to be near to 58A when the motor is locked.


texts: Does this criss-crossed GND plane look like it will function properly?

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I'll be using it at 12 MHz and...  not the best parts placement resulted in this board layout. So I am asking more experienced people if it will definitely not work or maybe it will. Thanks!

edit
I was referring to the current return paths and their loops caused by the GND plane gaps, not more complicated things than that.


texts:
I wanted to ask a relatively simple question:
Currently I am using a 3 phase AC motor that has a Gearbox torque of 5.1 Nm. A 16 teeth gear is attached to the shaft and this is connected to a 72 teeth gear using a gear belt.
So straightforward calculation would be:
Gear Ratio = 4.5 : 1
Output torque = 5.1 x 4.5 = 22.95 Nm ~ 23Nm
I need to replace this motor with a stepper motor with a holding torque of 2.7Nm.
Am I right in thinking that when the stepper motor is unloaded, each step (1.8deg) gives a torque of 2.7 Nm?
If that's the case, using the current gear ratio, would the output torque be 2.7 Nm x 4.5 = 12.15 Nm?
Secondly, if I was to use microstepping (32), does this calculation make sense?
1.8 step angle/ 32 microsteps = 0.05625 deg
Does each microstep angle output 2.7 Nm of torque or 2.7Nm / 32 = 0.084 Nm of torque?


texts: What is the best detection strategy for FSK and PSK demodulator

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I am Modulating the bits using FSK and PSK modulators and sending them to the demodulator and the demodulator is using simple zero crossing detection to detect the bits.

But the problem is, when I introduce a chennel between the modulator and demodulator, the channel output has many transitions going on and the detection fails some how.

So I am looking for any detection algorithm in Matlab, that does the perfect detection in a lossy and delay induced channel.

PS: When we calculate the BER of this communication system, we calculate irrespctive of out detection method ? I mean like, if my detection method is powerful then Bit Errors prone to happen more, and then should I blame that on that channel performance ? that is absolutely wrong I guess. So How can one know that he has the better detection algorithm in place before calculating the BER.

Hope I made my points clear, please let me know if you need more explanation, I am happy to provide.


texts:
I have a device running at 12vdc that has a pair of terminals that can be opened and closed for the device to operate. I understand how to use an optocoupler to open and close the terminals, however the twist here is that I need the terminals to be normally closed (ie to be connected most of the time), and opened when the opto is activated (eg by an MCU). This is preferred to keeping the opto activated due to wear (?) and the failure state.

The below was offered here when I asked about normally closed optocouplers, but I'm having trouble understanding how to integrate it, most likely because I don't fully understand how it works.

simulate this circuit – Schematic created using CircuitLab

What is the input to R4? Any available voltage? Where would I get that from? One of the terminals?
I also don't have a "load" as such - I just want to complete a circuit. Is that load implied (eg behind the terminals), or should I add a resistor?
Are there any other solutions to this? Although I see the value in an isolated solution, I'm interested in hearing in other ways to solve the problem. I also have regular mechanical relays which have NC terminals for instance.


texts: Downsides of 3-terminal capacitors and LC filters for power supply to IC

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I read the Murata application notes on power supply decoupling and noise filtering. I guess it works great as advertisement because I now want to replace all the decoupling capacitors to my analog-related ICs with something like this :

CF1, CF2 : NFM21 three-terminal capacitors

As a relative beginner in electronics, I'm fine with wasting money on this kind of overkill circuit, if I can just drop it in and reap the advertised benefits (less Vin noise, equivalent voltage buffering compared to MLCC decoupling caps).

Are there hidden downsides ?

For the sake of argument, Vcc is 3.3v from a LDO regulator (which takes 5v from dirty USB power). The analog parts of the circuit are: a CCD (IC2 on the schematics, TCD1304DG), an op amp (TL971) and an ADC (AD7380). The CCD is clocked in at 2 MHz, and there are 12-20 MHz SPI lines running on the board. I can more or less add this without disturbing the routing of the actual signals.


texts: How power dissipation in a transistor is less when signal is present?

texts:
My textbook says this

I get that the quiescent power dissipation is \$P_{DQ}=V_{CEQ}I_{CQ}\$. But, when a signal is present, the instantaneous Q point simply varies sinusoidally around the dc quiescent point. This means the instantaneous \$V_{CE}\$ and \$I_C\$ can go higher than \$V_{CEQ}\$ and \$I_{CQ}\$. I think this should cause some "additional" rms power \$P_{signal}\$ dissipated in the transistor; so shouldn't the total power be \$P_{DQ} + P_{signal}\$ ? I don't really get how \$P_{signal}\$ steals the power from \$P_{DQ}\$. Appreciate any help. Thanks!


texts: Why is my low dropout voltage regulator Diodes AP7370 burning up?

texts:
I'm building a LED driver using Diodes AL8871Q IC to power a XHP70 LED powered from a 4 series protected Lithium battery pack, integrated on the board it has an Attiny85.
I plan to use the Attiny85 to control the PWM pin on the AL8871Q, read voltage from an NTC thermistor. I am using a Diodes AP7370 SOT23 regulator to power the Attiny85 from the incoming 14v VIN.
Using a bench top power supply to emulate a battery pack, I set to 14V 1A and hook everything up including LED load. Powering on the PSU, all works, I can control the PWM of the Attiny85 which in turns control LED brightness.
Problem I have is when I tried with a battery the LDO regulator burns out. So I tried with a new LDO regulator, turning on the PSU before connecting to my circuit, it burns the LDO regulator.
I figured that the PSU has a soft start that stops the in rush of current vs battery or connect an already on PSU.
Is this what is happening? How can I prevent it from happening with adding the least amount of components.
Scenerios
PSU set to 14v 10A

Works Circuit is connected to powered down PSU, LED/load is connected. Power on PSU, Attiny boots up fine, triggers PWM that controls AL8871Q IC that powers the LED. All this happens almost instantaneously. Scopes shows PWM duty cycle at 40% as programmed on Attiny85. PSU displays shows 25W power drawn, voltage reads 14v and 1.8A+-.

Burns PSU powered on NOT connected to circuit. LED is connected to circuit. PSU is then connected to circuit. AP7370 burns up and breaks.

Burns 14.8V battery pack is connect to circuit, AP7370 burns up

Works Circuit is connected to powered down PSU, NO LED/load connected. Power on PSU, Attiny boots up. Scopes shows PWM.

Works Attiny85 & AP7370 removed from circuit, PSU powered ON then connected to circuit with LED connected. PSU displays shows 50W power drawn, voltage displays 6+V and about 8+A.

Schematic has 7805 labelled wrongly, it should be AP7370

<img src="https://i.stack.imgur.com/rqhID.jpg" alt="Photo of scope when connecting to a 11.1v
Battery with LED connected. " />


texts: USB 3.1 Gen 1 Transfer Speed Through Hub

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If I have a USB Host Controller that supports USB 3.1 Gen 1 plugged into a hub, and 2 storage devices connected to the downstream ports, if I transfer data from one storage device to the other through the hub will the speed be 5 Gbps or 2.5 Gbps? I understand that USB 3.1 Gen 1 has full duplex communication, but I'm not sure how that will interact with the host controller.

If the speed is indeed halved, is there any way of increasing it short of finding a host controller with 2 USB ports?


texts: Charging battery simultaneously from 2 sources

texts:
This is my first time posting here.
I have an issue, I want to charge battery from 2 sources simultaneously, but I am kinda a worried about how that might work.
If I add the voltage feedback directly to battery then one charger might trick other charger. I guess I could put diodes, but I have a feeling this might make me another trouble. Of course instead of diodes I can use Mosfets for lower power losses in this load sharing.

Have any of you guys tried something like this? Any advises?


texts: Using a manufacturer specific Profile and Cluster on NXP JN5168

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I am writing a ZigBee application on NXP JN5168 MCU.

I would like to create a custom Endpoint with a custom Cluster defined by me instead of one from the ZigBee Cluster Library.
Looks like I'm forced by the SDK (1) to use either the full ZigBee Smart Energy profile or Home Automation profile. NXP's ZigBee PRO Smart Energy API User Guide - Appendix B states that I can setup custom Endpoints by declaring the appropriate data structures, calling a function to create the Endpoint and then calling the function eZCL_Register().
I found all functions to create supported clusters from ZigBee Cluster Library but I cannot see wich function to call to create a custom cluster, if any exists.

I checked their ZigBee PRO stack User Guide and nothing is said about custom cluster creation.
What I've found is an old example for the previous family of chips (JN514x) wich uses custom profile and clusters but it's pretty much useless.

Any help on this topic will be appreciated. If it cannot be accomplished (e.g. no real support for customization or Manufacturer Specific Clusters) a denial will be helpful too.

(1) I remember reading somewhere that the "pure" (without standard profiles) ZigBee Pro stack use is deprecated or not supported on newer JN516x chip family.


texts: Reading a 1.2V-8.8V Signal into a 5V Arduino Input

texts:
An analog DC signal that ranges from 1.2V to 8.8V (from a thermocouple amplifier) is to be read from a input pin on the Arduino that reads 0V to 5V.

Other that using a potential divider consisting of 2 resistors to drop the signal down to 0.6V to 4.4V, is there an alternative method that exist, like one that uses a IC?


texts: Function of earth screw terminals in power supplies with plastic cases

texts:
This is about use of earth screw terminals which are often provided in power supplies.

Below is an Embedded Switch Mode Power Supply with a metallic case:

Here I can understand how the earth wiring is useful in case of line is touching to the case. This would save someone being exposed to line voltage.

On the other hand below is a DIN Rail Power Supply with a plastic case:

It also has an earth terminal. In this case how is the earth wiring useful since the case is already insulator itself (plastic)?


texts: Interfacing Current shunt monitor with 16bit ADC

texts:
I am supposed to high side current measurement via shunt resistor (between source and load) and feed it to the microcontroller. For that purpose i have decided to use this IC MAX9922 which is a ultra high precision current sense monitor. The reason for selecting this IC is its high accuracy of measurement. The output of this amplifier would be fed to a 16 bit ADC ADS8319 which would then provide the digital data to the micro-controller via SPI interface.

Now while designing the circuit schematic, i came to find out that ADCs require OP-AMPS (to act as a low impedance buffer) plus RC filters (for filtering out unwanted frequency signals) on their input. And the Amplifier ICs plus the values for RC filter to be used are given in their (ADC's) datasheets normally. For eg in ADS8319 datasheet on pg no. 21 the recommended OPAMP plus the values of RC filter are given.

My question is that, as i am already using MAX9922 (for current sense measurement), is it necessary for me to insert a buffer OPAMP in between the MAX9922 and ADS8319 ? As i think my signal is already coming to the ADC from an Amplifier IC, i could just straight away (with an RC filter) feed it to my ADC input without inserting the buffer. Am i Right about it ?

Also, in MAX9922's data sheet (on page 13) the maxim IC is shown to be connected to a 12-bit ADC as an example circuit. However i would be connecting it to a 16-bit ADC. I hope that it would work as expected in my case as well. There wont be any issue about it. Am i right ?

Your helpful suggestions and comments would be appreciated.

Thankyou!


texts: Why is the effective base resistance important for the voltage divider BJT amplifier?

texts:
I came across many questions regarding the below type of biasing where they explain and analyze Rth Vth and conclude that Rth must be very small comparing to Rin. Rin is the effective resistance seen by the input. I have made the following drawing for transformation of the input as follows:

I can understand that the bigger the Rth the more we will have voltage drop across Rth. Some call it loading and say that it affects stiffness. I dont get it why. Everything is constant irrespective of the value of Rth. Isn’t it?

I cannot really explain myself why it matters as long as we calculate all the node voltages. Can you give an example where we can see that the relative value of Rth to the Rin matters?

If possible a simulation would help.


texts: Do the wattage from connected devices need to add up with the given wattage from a step-down converter?

texts:
A step-down buck converter converts 36V to 12V 36W.
Does it mean that the sum of all the wattage from all connected devices need to be 36W? OR Does it mean that I can connect multiple devices not producing more than 36W power?


texts: Audio - How does I/O impedance affect the device?

texts:
Last year I was experimenting with a design for an audio distortion to be used on line level musical instruments (+4dBu with Zout 100-600Ω by my findings) without the knowledge of impedance, its importance, and how to "use" it. After learning of impedance bridging, I returned to the design and saw that, although it worked as I intended, my impedance was "backward," having a lower Zin (approx 1.7kΩ), and higher Zout (8.2kΩ).

So, concerned about damaging my equipment, I did quite a bit of research, and found lots of information on how impedance affects the signal, and that a low Z input causes loading on the source, but nothing really clear on how the source itself is affected.

So my questions are:

If one were to hook up two devices in this fashion - feeding an audio signal into a load with equal or lower impedance than the source - are there any long term adverse effects on the equipment itself?
Understanding that 10x the source is the rule of thumb, and that something like 4Ω is nearly a short, what ratio to the source would begin to be damaging for a longer duration than something like a plug insertion?

I've learned to adjust my future designs, but am still curious.

Thank You.

Note: This question has been completely rewritten, so for some of the answers/comments to make sense, see the edit history, where you may also find more detailed information on my specific situation, which upon further thought, only brought about the curiosity that is more simply state above, and is mostly irrelevant.

Thanks again.


texts: Common Mistakes Using Breadboard: What's Wrong?

texts: I didn't wire my circuit correctly and burnt out all my LEDs. I put the resistor's nodes in the same 5 hole row and put each terminal of LED in separate rows. The LED lit up, but soon after blew up. Why can't the resistor or the LED terminals be placed in the same 5 hole row?


texts: I'm super new to electronics and am wondering if there is anything that behaves like the reverse of a shift register... as in parallel in and serial out instead of serial in and parallel out.  I know there are multiplexers, but they don't seem to operate in the same way as a shift register (with latch and clock signals), thanks.


texts: Unable to delete circle in tDocu layer in Eagle

texts:
I am making a revision to my PCB board where the initial mounting holes were too large and therefore decreasing their size.

The holes are on the Dimension layer (20) and were created using the circle tool, located near the bottom of the left column and pictured below. When decreasing the dimension or deleting the holes completely, a circle of the original size still remains which is on the tDocu layer (51). I am unable to select it and therefore I am unable to remove it.

Is there a way to delete this circle which is present in the tDocu layer? It does not affect my board design as it is not included when manufactured, however it may cause confusion at a later point.

Here are some screenshots:

This is what it looks like prior to deletion.

This is the remaining tDocu circle.

This is the result when trying to select the region.


texts: Operating Voltage and Current of solar PV panel connected directly to a battery

texts:
Let's assume we have a 60 cell 260W PV panel with the following STC characteristics:

Voc= 38.1V
Isc=8.98A
Vmpp=31.1V
Impp=8.37A

The panel is exposed to direct sun light and standard conditions are present (1000W/m2 and 25C). The panel is connected directly to an automotive type, 12V lead-acid battery without any dc-dc converter. The internal resistance of the battery is 100 milli-Ohms.

What would be the approximate operating voltage and current of the solar panel connected to the battery, assuming it is not fully charged.


texts:
I have the following circuit :

It is meant to amplify signals in microvolt range and around 100 MHz. Now in the figure, the transistor is an ideal one. So it works fine and as expected. But as soon as I replace it with actual model, it doesnt work . I need either 2n3904, 2n2222 or bc547. And all three dont work. I tried tinkering around with capacitor values, but no use.

I have seen a few radio receiver schematics for FM ( 88 to 108 MHz). All of them make use of 2n3904 for RF Amplifier ; so it must work for my scenario as well, but it doesnt. (I referred to those Elenco radio kit manuals).

What am I missing ?

More info : Q - point : Vce = 6.3v --- Ic = 3.9 mA ---  Vcc = 12V

Thank you.


texts: Finding a CPU's Capacitive Load - Computer Architecture

texts:
I'm new to computer architecture, and found a question similar to that on this site already with actually quoting the same text book. I'm struggling to figure out if the answer is 1.77Ghz or 3.55Ghz. Could someone people provide some explanation to what it might be?

You are asked to modify an old CPU which runs at 2GHz and design a new CPU with 55% less power
consumption. The use of a new technology helps to reduce the capacitive load in the new CPU by 40% and
the voltage by 35%. Calculate the clock frequency, which needs to be adopted by the new CPU such that
the power consumption of the new processor is reduced by 55%.

At first I thought it would be 3.55Ghz but then when I tried writing out the question, I noticed I could just cancel out the 2Ghz as it's the old frequency and it can be found on both the bottom and top of the equation (according to lecture notes). Appreicate any feedback!

Example found in notes:


texts:
I would like to know if using two 2.5mm² cables has a greater current rating than one 6mm² cable.  The ratio of CSA is 2.4x and so I would have expected to need three 2.5mm² cables. However, I then looked at the actual current ratings tables for different cable sizes and see that 2.5mm² is rated at 18.5A while 6mm² is only at 32A.  Hence presumably two 2.5mm² cables would have a joint rating of 37A and so exceed the 6mm² cable.

I have read other posts that the deciding factor is the amount of copper, which would suggest that three 2.5mm² cables are needed.

However based on the current rating tables, only two cables are needed.

So I don't understand why the tables contradict the advice in posts on this site.
I would like to know if I have understood the tables correctly, or if my logic is flawed.

Also, my cable is single strand.  Should I use multiple strand, as this seems to be used in the tables?

Source: http://www.diydoctor.org.uk/projects/cablesizes.htm


texts: How does this non-isolated buck converter work?

texts:
I found this converter-circuit on the Internet. I will use it to power an IR2153, which contains a 15,6V zener.
I chose to use it because of the large losses of a resistive dropper.
The unmarked voltages are unknown.
Diodes- high speed (BA159, UF4007 etc.)


texts:
Firstly, I am new to EE.SE as well as to Arduino.  I just figured out how to write code for the chip in Arduino.

Well, I am connecting a camera on the board, which continuously sends some data. this data could be caught by the sketch that would be flashed on the board.

My question was how could the output from the Arduino be received on my computer. Can it be done using a .NET based client on the desktop.


texts:
I have a DC to DC converter that outputs 28v and charges a very large cap. (10mF).

Cap acts as an energy source for a load that consumes lots of energy for a very short time. (A few amps for micro seconds).

I currently have a small resistor between cap and DC DC converter and this solves the inrush current and ensures we don't burn DC DC converter.  However I like to improve this circuit and do a more sophisticated current limiter which can pump up to 100mA to capacitor regardless of its voltage level. (Current solution pumps current based on the voltage level of the cap. If voltage is very low, resistor allows a larger current. But say if the delta is 1v, resistor allows a smaller current to pass through. )

Ideally I like a solution where I can pump up to 100mA even when the voltage on the cap is slightly below the 28v.


texts:
This is more of a mathematics question than an electronics question but what is the solution of this differential equation

$$α = \frac{V}{RC} + \frac{đV}{đt}$$

This solution gives the time response of the Ramp input in RC circuit. Can anyone show me the math behind it? The solution comes out to be

$$V = αRC(1 − e^{−t╱RC})$$


texts: Stopping DC motor when motion being blocked without a limiting switch

texts: Is there a way to stop a DC motor when its motion be blocked ? For example if it rotates in a free motion raising a load and the load reached a blocking part making the shaft not rotating while the current is on, ( without using a micro limiting switch).


texts:
I'm no engineer and am no electronics type person at all.

I friend suggested I post my question here.

I have a solar powered keyboard that uses an ML2032 3v lithium battery. I ordered a new one and received an LIR2032 3.6v battery.

Will the higher voltage battery give me problems?

thanks for your patience with me. :)


texts: How can an optocoupler detect the zero cross point in an AC wave?

texts:
I am having some trouble using Triacs in order to dim a light bulb operating at 220V AC, I am a student at school and I don't have any background about using Triacs or Diacs or so, so I seeked the internet for circuits which uses a microcontroller in order to control the Triac to control the speed of an AC fan or brightness of a light bulb.

So I got this circuit which I understand it all except there is a part I didn't understand in the circuit so that's why I am asking here for help.

So my question is concerned about this IC the MCT2e which I think is an optocoupler, how can this IC detect the zero crossing in the AC wave ? Although the input in this IC is rectified using a bridge rectifier ?
And also what is this IC properties ? Can any general purpose optocoupler be used or there is special specs. For it ? in short I want to know the principle of how this part of the circuit works in order to detect the zero crossing point in the AC wave.

Thanks in advance.


texts: Problem mapping VHDL onto development board

texts:
I have a very frustrating problem and would really appreciate some help.
I am trying to test a RAM block using the switches and LED's on board the Nexys A7-100T FPGA development board. My code is synthesising fine but fails on implementation due to the errors shown in the image below.
I have also shown my constraint file and top level code file.
I am new to FPGA boards and I am unsure what I am doing wrong. I have tested this code on testbench and it works perfect. Would like to map it onto the FPGA to learn how.
EDIT
I have the clocks commented out in the constraints file as they caused even more errors.
Thanks!

Constraints file

#create_clock -period 10.000 -name clk -waveform {0.000 5.000} [get_ports clk]
#set_property -dict { PACKAGE_PIN E3    IOSTANDARD LVCMOS33 } [get_ports { clk }];

set_property -dict { PACKAGE_PIN P17   IOSTANDARD LVCMOS33 } [get_ports { Set_Button }]; #IO_L12P_T1_MRCC_14 Sch=btnl
set_property -dict { PACKAGE_PIN M17   IOSTANDARD LVCMOS33 } [get_ports { Enable_Button }]; #IO_L10N_T1_D15_14 Sch=btnr

set_property -dict { PACKAGE_PIN J15   IOSTANDARD LVCMOS33 } [get_ports { RAM_Address[0] }]; #IO_L24N_T3_RS0_15 Sch=sw[0]
set_property -dict { PACKAGE_PIN L16   IOSTANDARD LVCMOS33 } [get_ports { RAM_Address[1] }]; #IO_L3N_T0_DQS_EMCCLK_14 Sch=sw[1]
set_property -dict { PACKAGE_PIN M13   IOSTANDARD LVCMOS33 } [get_ports { RAM_Address[2] }]; #IO_L6N_T0_D08_VREF_14 Sch=sw[2]
set_property -dict { PACKAGE_PIN R15   IOSTANDARD LVCMOS33 } [get_ports { RAM_Address[3] }]; #IO_L13N_T2_MRCC_14 Sch=sw[3]

set_property -dict { PACKAGE_PIN H17   IOSTANDARD LVCMOS33 } [get_ports { Data_out[0] }]; #IO_L18P_T2_A24_15 Sch=led[0]
set_property -dict { PACKAGE_PIN K15   IOSTANDARD LVCMOS33 } [get_ports { Data_out[1] }]; #IO_L24P_T3_RS1_15 Sch=led[1]
set_property -dict { PACKAGE_PIN J13   IOSTANDARD LVCMOS33 } [get_ports { Data_out[2] }]; #IO_L17N_T2_A25_15 Sch=led[2]
set_property -dict { PACKAGE_PIN N14   IOSTANDARD LVCMOS33 } [get_ports { Data_out[3] }]; #IO_L8P_T1_D11_14 Sch=led[3]

Top level file

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use work.Architecture_size.ALL;

entity RAM_Block is
 Port ( RAM_Address : in std_logic_vector (Data_width-1 downto 0);
        Data_in  : in std_logic_vector (Data_width-1 downto 0);
        Set_Button : in std_logic;
        Enable_Button : in std_logic;
        Data_out : out std_logic_vector (Data_width-1 downto 0));
end RAM_Block;

architecture Behavioral of RAM_Block is

component Enabler_Block is
 Port ( A : in std_logic_vector(Data_width-1 downto 0);
        Enable : in std_logic;
        Q : out std_logic_vector(Data_width-1 downto 0));
end component;

type memory is array (0 to 3) of std_logic_vector (Data_width-1 downto 0);
signal RAM : memory := ("0000" , "0000" , "0000" , "0000");
signal RAM_output : std_logic_vector (Data_width-1 downto 0);
signal RAM_Address_int : integer;

begin

Enabler_Block_instance : Enabler_Block port map (A => RAM_output , Enable => Enable_Button , Q => Data_out);

RAM_Address_int <= conv_integer(unsigned(RAM_Address));

   Process (Set_Button , Enable_Button)

    begin

     if(rising_edge(Set_Button) and Set_Button = '1') then
        RAM(RAM_Address_int) <= Data_in;

     end if;

     if(rising_edge(Enable_Button) and Enable_Button = '1') then
        RAM_output <= RAM(RAM_Address_int);

     end if;

    end Process;

end Behavioral;


texts: Which optical sensor to detect polypropylene wipes pass by?

texts:
Which sensor should I use to detect that a polypropylene sheet (light
shines through) has moved past a certain point? Would be nice if
it could easily connect to an Arduino.


texts: Best way to tell Altium that two pins are internally connected

texts:
So I'm making a shield for a Raspberry Pi, and as you all Know the GND pins are internally connected inside the Raspberry. How can I tell that to Altium, so that It don't asks me to route them?

Altium thinks that pins 6 and 9 are not connected, but they are. (Internally)

Full PCB image:


texts: Switch on set of 6V battery powered lights from raspberry Pi

texts:
I want to switch a set of lights (LED) wired in (what looks like) series on and off very quickly using the GPIO pin on a Raspberry Pi. The lights can be found here:

http://www.diy.com/departments/blooma-gelanor-battery-powered-white-10-led-string-lights/1283455_BQ.prd

The lights are driven by four AA batteries, so 6V in total. The box says that there are 30 bulbs at 0.06w each. I think this means that it'll be drawing 300mA.

Can I use a transistor to switch this or do I have to use a relay? Any recommendations for appropriate transistors would be greatly welcomed too.

EDIT

So I splashed out and got myself a multimeter. I tested the current on the string and it's coming out at 12.4mA. If I take the wattage of the whole string as 0.06W rather than each bulb and the voltage as 4.8V (for rechargable batteries) then this ties in with my sums (12.5mA). Does this change things? Could I get away with a single transistor. Arbitrarily, would this work: http://cpc.farnell.com/fairchild-semiconductor/fdd5614p/mosfet-p-d-pak/dp/SC11192

Thanks again for everyone's patience with probably a very simple problem, just don't want to blow up my pi (or set my house on fire!)

EDIT 2

I took a closer look and it looks like all 30 bulbs are actually wired in parallel. Each wire in each bulb is two wires which don't connect at the end and don't feed back in to the base of the bulb:

Each individual LED is quite small, I've taken a photo of them next to a standard LED for comparison:

Does this make my measurement of 12.5mA over 6V more feasible?


texts: Understanding CS5463's basic circuit power supply

texts:
I'm trying to put the CS5463 chip functional using the example circuitry on page 41 of the datasheet (attached bellow):

Right now, I'm working on the top part of the circuit, which is the IC power source. I've ran some simulations on Multisim and, apparently, this part is completely functional. But before proceeding to some other part of the circuit I want to understand what every component is there for. I did my research so I didn't arrive empty-handed.

The 470 nF capacitor: is it a decoupling capacitor, which filters a possible DC signal from the power line? I couldn't extract this information from my simulations. I had the impression that it does something else…
The 500 ohms resistor in series with the capacitor mentioned just before… Is it a simple current limiter? My guess is yes, it is, and its function is to limit the current from the negative cycle of the power line.
From the simulations, I've learned that this capacitor and resistor in series are exposed to great voltages. The capacitor, for instance, is exposed to tensions up to 295 Volts (the power grid I'm on is 220 Volts RMS). Are there any capacitors of the order of nanofarads that can handle that much?
About the diodes: the first one is there to close the circuit on the negative cycle. The second one's purpose is to prevent the power grid to drain energy stored on the 470nF capacitor when the power grid is on the negative cycle.
The 470nF capacitor: is the component that charges energy from the positive cycle of the power grid to discharge it on the negative cycle.
The Zener diode: works as a voltage regulator, keeping the voltage on, approximately, 5 Volts.
The 500 ohms resistor before the Zener diode: creates a voltage difference between the 470uF capacitor and the Zener diode when the loaded tension on the capacitor is greater than the one the zener diode is holding (approximately 5 Volts).

Are my hipothesys correct?

The 0.1 uF capacitors: would they be by-pass capacitors? Would they function as a "virtual ground" for the AC signal?
Why there is a 10 ohms resistor between the VA+ and VD+ source pins? Why are the AGND and DGND ground pins short-circuited?
I chose the 1N4733A to be the Zener diode. Is it a easily found component (local stores)? Would there be other suggestions?


texts: Can this capacitor move this solenoid kicker

texts:
I'm buying this solenoid:

The data are:

Voltage: 12V DC
Current: 8A

I need to build a kicker: push a button, capacitor charge, when is charged the solenoid kick an object.

I want to do it with Arduino, and I have a 2-channel relay module 12V with optical coupler protection.

When I push a button with the first relay channel I charge the capacitor using a
DC-DC boost converter 8~32V to 45~390V booster module 40W, and when the capacitor is fully charged, I will power the solenoid with the second relay channel.

I tried to read something, but I don't understand if a 4700μF 63VDC capacitor is ok for my circuit.

Links: Video 1, Video 2

This is basically my circuit: I want to use a cheaper capacitor and I want to use a typical DC power source instead of the battery.


texts: Will GPIO still be available when connecting a BoosterPack on any Launchpad?

texts:
I had this question in mind while exploring the BoosterPacks for the TI Tiva C series launchpads. Let's say you connected KenTec display to the board, you still have access to the female headers on the bottom of the board. The question is when the display is operating and functioning, will you still be able to use any GPIO for other external circuitry or systems or anything ?

The question applies on any other boosterpack.


texts: The relay shown below [Link] claims to trip in less than 25 ms to fault currents that are 5 x greater than the set trip current. Also the minimum time settings are inst (what time is "inst") and 50 ms. How can one find reliable RMS for both 50/60 Hz in that short amount of time? The minimum time interval where both 50 and 60 Hz signals are almost synchronized is 100ms (6 cycles of 60Hz and 5 cycles of 50 Hz).


texts: Chopper Amplifier feedback loop stability

texts:
I have a question regarding the stability of a circuit I plan on building. This is a voltage-controlled current source, with the IN-AMP being used to sense the current through Rsns and provide feedback to the op-amp. I'm trying to use a programmable instrumentation amplifier and turns out most of the ones that fit my requirements are chopper amplifiers.

However, as I understand it this means there will be some delay from when the current through Rsns changes to when the capacitors in the chopper charge and discharge, and then the output of the in-amp is changed. Am I correct in assuming this delay will lead to oscillation? (I don't have the parts yet or I would just build it up). Is it in general a bad idea to introduce delay elements into a feedback loop, or is there a way to use them without instability? Thanks!

UPDATE:
For those that would like an update: I built this circuit with a vanilla op-amp and instrumentation amplifier, with the instrumentation amplifier having a G=100, Vin= 1Vpp sinewave at 60Hz, Rsns=1R, and ZL=22R, and I see my 60Hz signal "amplitude modulated", if you will, at an oscillation frequency of 133kHz. Here is the oscilloscope trace across ZL.


texts: What exactly are surface charges and what do they do?

texts:
How does the voltage/electric field of the battery relate to the surface charges on the wire?
What determines the amount of surface charge on the wire? (Why more near the battery, less farther away)
What are the surface charge doing?


texts:
Recently I have learned about the behaviours of capacitors are as follows:

When connected to a voltage source the voltage on the the plate on the positive side begins to rise slowly until it reaches the same voltage as the supply, while the other plate, which is connected to ground, remains at 0v.
Capacitors have the tendency to keep the voltage across two plates the same, and therefore if one is 10v and the other is 0v, and the 10v is suddenly pulled to ground, the other plate will be pulled to -10v to maintain the voltage differences.

These two statements seem contradicting to me. Specifically, if capacitors tends to keep plates voltage the same, then why when it charges, the other plate remains 0v? And unlike voltage rising(charging) which happens gradually over time, why does the plate voltage  change from 10v and 0v to 0v and -10v instantaneously when pulled directly to ground, that is, why in this case it doesn’t lower its voltage gradually over time?


texts: measuring -3V with 3 resistors voltage divider

texts:
I know (or may be think) that I can scale the measurement of a 0 to -3.1V external battery to a analog pin ADC range of 0 to 3.3V, but I'm unable to calculate the resistors.
I've been trying how to do this by thevenin, but with no luck...

The schema (I think) would be the following:

simulate this circuit – Schematic created using CircuitLab

I just want to know the resistor values to measure V1 (V2 have no effect here) but I'm unable of calculating resistor values...
Any help?


texts: I am building a project and I've come across a problem I can't solve. I need to have an output of about 5 seconds when a button is pressed. Is there any way I can do that?


texts: Where are the power, ground and LED connections on this car air conditioning PCB?

texts:
I ordered a PCB for my car air conditioning, as the old one was chewed off by rat. I lost the plug and I'm totally confused which wire would fit where. Can someone please help me in locating which pin is ground and power and LED?
PCB has 6 pins, so 6 wires to connect.
3 wires will work for a switch, LED and ground. So in total 2 switches, 2 LEDs and 2 grounds, making it 6 wires.
Below are pictures of the front and back of the PCB, and I would really appreciate help.


texts: defining base frequency, multiplier and divisor for dynamic clock manager

texts:
I am using a Spartan 6 xilinx FPGA, I managed to get it all working, changing the multiplier and divisor parameters at runtime. DCM_CLKGEN I use.

My real oscillator is 66.6 MHz, but with PLL_BASE, I can change it.
As we need a clock frequency from 1 to 100MHz, I am wondering, what base frequency would I take? I set it to 40MHz, just to choose something, that seemed nice....

FREQUENCYout = FREQUENCYbase * MULTIPLIER / DIVISOR

I made a simple spreadsheet to see how different multipliers and divisors convert the base frequency, some divisors on the column headers, some multipliers on each row, so I get a matrix of possible outcome frequencies. Although not for every frequency (It would get bulky). I can't believe trial and error is the way to define those parameters, but surprisingly, I don't find much information on the net about it.

The divisor and multiplier have to be integers (no floating points), otherwise I could just choose "any" multiplier, and calculate a divisor, by completing the equitation.

summary:

question 1: base frequency for a wide range of output frequencies.
question 2: a general way of working for defining the multiplier and divisor.


texts:
I wanted to use the Square-Root Operation of the FPU (6.1) in the Xilinx's Logic Core IP. I don't know what latency should I choose. Can someone help me with that?

By default it chooses the maximum possible latency. Why would anyone want to choose the maximum possible latency?

I will be using it on a Xilinx Virtex-6


texts: Know of any inexpensive UHF RFID reader modules?

texts:
I am evaluating RFID tags for a project, and would like to minimize the cost of the tags.  We can find UHF (EPC Gen 2) tags for much less than HF (Mifare UL) tags.  Unfortunately, the least expensive reader/writer module I could find for UHF tags is about $200, whereas the least expensive module for HF tags is closer to $20.

Are there any less expensive (< $50) UHF RFID reader/writer modules available?  Is there something inherent in the UHF band that makes it more expensive to build an RFID reader/writer module?


texts: What is the purpose of these diodes in this opto isolator circuit?

texts:
I came across this circuit which I think is to isolate a high voltage signal to a safe level for GPIO of a 3.3V micro controller.

My question is that how on earth this circuit works...There are 2 high voltage levels (28v and 12v) and BE_OPEN is a ~24V/0V signal...which I think comes from a push button.

What V16 does here? doesn't it block any currents that tries to go to pin #3 of the opto-coupler?

What about Z3 (zener diode)...what will happen if we remove it and just short to ground?


texts: How do you increase the torque of a DC motor?

texts: I'm an engineering student and I study at an engineering college. Our college has technical festivals. I took part in one last year, I built a robot using 4 dc motors (300 rpm and high torque) and I lost. My opponent has the same  motors but she has a better design so I want to increase my motors torque. Could you please advise me - how do I increase the torque of my motors.


texts:
I have built a Ponyprog programmer to find out Windows 7 cannot recognize the drivers.

I was wondering if I could use this "Pocket AVR Programmer" to program an atmega 8535?

If so, how do I connect the atmega to this board?

Or can you recommend something for me?


texts: Advantages and disadvantages to loops in VHDL unrolling

texts:
The question is as follows:

  Identify and explain two potential advantages and disadvantages of loop "unrolling"

While searching the internet I came across these two resources:

Resource One
Resource Two

But all I could really discern from them is that loop unrolling allows parallelism to occur in the system and not really why this is a good or bad thing. Although I know that the whole point of an FPGA is allow things to run in parallel, a feature (loop unrolling) that makes this possible doesn't seem like an advantage.


texts: I'm still new to electronics and I am trying to do a calculation. Say I have a 100 Watt bulb that runs at 120V and my source is 240V. I know the bulb will blow but my question is: if I wanted to put a resistor in the circuit how will I calculate the amount of resistance I would need?


texts: Why base current changes with collector emitter voltage?

texts:
There are two questions in stack exchange similar to mine, but I though mine was more basic and also more specific.

I tried doing some SPICE simulations in order to understand transistor characteristics described here, but using a real transistor, i.e., 2N2222. I tried two circuits as shown below. As you can see, both circuits are very similar with Vbe, Vcc being exactly the same between the two. The only difference is that the one on the right has 100 ohms more between Vcc and the collector. I expected Ib to have the same waveform between the two circuits - but when I saw the simulated waveform, Ib on the right circuit (blue color) seems to different from the Ib of the left circuit (green hiding behind the blue signal for the most part). The red signal is the Vce of the left circuit and the blue green signal is the Vce of the right circuit.

What I have read in many books, literature online (including the one I have referred here), is that Vce has no effect on Ib. And yet, my observation is different! Can anyone kindly explain this strange behavior of Ib? Many thanks in advance.


texts:
Would like to have a simple milliohmeter for car wiring checking. Precision is not important, it's not about 3 vs 4 mΩ, it's about 3 vs 30 vs 300 mΩ.

Simple idea is a 1A floating current source (2 alkaline AA batteries and a very basic circuit) and using an ordinary multimeter to measure mΩ as mV in a 4-Wire connection.

An important point is that the circuit survives most possible abuses, specially being connected directly at +/- 12V on the RX terminals. I think it will survive having -12V at Q2 collector but I'm not really sure.

Will have to see if two AA are enough or it needs a third to go 4.5 V.

Do you think this would work? What would you change while keeping it cheap and simple?

simulate this circuit – Schematic created using CircuitLab


texts:
How can I use malloc() and free() functions in a PIC?
I've checked the stdlib.h header and there's no mention of them.
I'm using MCC18.

Has anybody had to use them?

I need them because I am porting a library from Windows XP to the PIC. The porting guide says to

  adapt the Operating System's specific
  functions to my PIC ones

But I don't know how to "translate" the malloc() and free() functions.


texts: Double ethernet magnetics for a passive medical application

texts:
I am designing medical data acquisition equipment that requires moderately fast data transfer. As part of the design we are using a custom 100BASE-T PoE architecture (and cabling) to the data acquisition headstage, together with an intermediate "dumb" device to (1) provide medical-level isolation, (2) inject PoE power, (3) connect ethernet to the computer, (4) connect additional non-isolated equipment (via two extra ethernet pairs from the headstage, that's why we are limiting to 100BASE-T).

The only medical-grade isolated magnetics I can find are the HXU6200NL by Pulse, which will serve to connect to the computer and will reside inside the dumb device isolating the headstage itself.

The question is: Would it be ok to use two sets of ethernet magnetics back-to-back inside the dumb device?

That is, to use a second set of PoE magnetics to inject power and connect to the headstage with no intermediate circuitry (besides, perhaps, some common mode terminations for both cables).

Edits:

There will be a standard set of magnetics in the headstage bringing the total count in the link to 4 (the absolute minimum to provide the needed isolation would be 3)
The total cabling length (headstage-box-computer) would be less than 10m, very likely less than 5m.
One reason to want to use a second set of magnetics is to provide "standard" common-mode termination (i.e., Bob Smith termination) to each cable segment.
Another reason is that ethernet magnetics are not symmetrical, as common-mode chokes and autotransformers are commonly present.


texts:
Maybe my question will be very basic but I am newbie and I have stucked...

Supoose we have uC and one pin (voltage is in range 0-3v3) connected to external interrupt. Which of these sentences is true?

The falling edge interrupt would fire when voltage goes down from 3v3 to lower value (for example from 3v3 to 3v1).
The falling edge interrupt would fire when voltage goes down from 3v3 to 0 volts

Which of them is true? Thanks!


texts: Programming/Verifying EPROMS with an elevated VCC

texts:
Many EPROM manufacturers specify a faster programming algorithm which involves temporarily raising VCC from 5V to about 6V.

If I read with this higher VCC in place, are the outputs still limited to the 5V vcc, or does my reading circuitry need to be 6V tolerant? Similarly, going in the other direction, are the EPROM inputs (data and address) 6V tolerant?

I haven't any specific EPROM manufacturer in mind: they all do variations on this theme, but the data sheets seem to be silent on this issue. They all seem to quote a maximum logic input of VCC+0.5, with out saying -which- VCC.

Maybe I'm over thinking this.


texts: Selection of PWM switching frequency in BLDC motor

texts: Is there any method or formula for selecting PWM switching frequency based on measured motor parameters for controlling BLDC motor?


texts: Selecting a DC-DC voltage inverter/regulator

texts:
I'm trying to select a DC-DC voltage inverter/regulator which can take a 5V USB input and output -5V for use as Op-Amp power supplies.

I've identified 2 potential candidates:

TI's LT1054
Linear's LTC1983-5

As far as I can tell the main difference between the two is the switching frequency (~25kHz for the LT1054, ~900kHz for the LTC1983). I did a little research and supposedly the higher the switching frequency the more stable the output voltage is, or the smaller the output capacitance needs to be to maintain the same output stability.

I would prefer to have just one charge pump to power 4 op-amps (3 IC's, one is a dual package). The op-amps are:

Micrel's LMC7101 (2x)
National Semiconductor's LMH6612 dual op-amp (using both amps)

The LMC7101's are being used as nearly constant voltage level buffers and the LMH6612's are being used to buffer signals (anywhere from close to DC up to a few MHz). Looking over the datasheets the LMH7101's have a supply current of at most 1.7mA and the LMH6612's have a supply current of at most 4.85mA per channel. This means I should be drawing at most 13.1mA to power these chips.

As far as cost goes, the LTC1983-5 is $4.28 and the LT1054 is $2.87 through Digikey. However, the LT1054 example schematics use 100uF caps, which are significantly more expensive than the 10uF caps used by the LTC1983-5 especially for high-quality low ESR ones. The LT1054 also requires larger input capacitors.

Is my analysis here correct? What other parameters should I take into account? And most importantly why should I pick one over the other (for reasons other than cost, if any)? Are there any other recommendations for other solutions I should look into for providing the +/- 5V Op-amp supplies? I am limited to the 5V input from USB.


texts: I've a project where I'm installing some LED lighting. I am currently using crimp connectors and electrical tape to join two pieces of wire or fork wire, but I find this to be ugly. I would like to know what solder-free alternatives there are to joining two wires or forking wires into 2 or more wires that have a fairly low profile and form good mechanical and electrical connections. The wiring is probably 1-2mm in diameter including insulation.


texts: Can I use 104 k 250v ceramic capacitors in a Jacobs ladder circuit? Do I need to use higher rated ones? I'm salvaging some of my components from a used CFL.


texts:
I have system that 98% of the time consumes less than 300mA. The remaining 2% it consumes 550mA. It is a USB system and works with a PC. I have looked at various options to stay withing the 450mA target power consumption but I couldn't bring it down. I cannot take risk with system malfunctioning due to longer cable or poorly designed USB power of a PC, therefore I was thinking of adding a battery with power path IC so that during the peak period the current can be augmented from the battery.

The down side of this is that the battery will always be in charging mode. I have no idea what this would to the battery. Any insights would be appreciated. I need this product to work for 3 years without a hitch.


texts:
I would like to know why my PIC which when I put in to deep sleep does consume more than what is specified by the datasheet. I have connected a precision current meter and found that when I load the code which makes the controller to enter deep sleep it consumes 0.27mA as to the 860nA rating given. I would like to have your insight for the problem. I have done the testing on a PCB with crystal for 16 MHz and for RTCC. Why is it showing this much consumption?

// PIC18F26J50 Configuration Bit Settings

#include <p18F26J50.h>

// CONFIG1L
#pragma config WDTEN = OFF      // Watchdog Timer (Disabled - Controlled by SWDTEN bit)
#pragma config PLLDIV = 1       // PLL Prescaler Selection bits (No prescale (4 MHz oscillator input drives PLL directly))
#pragma config STVREN = ON      // Stack Overflow/Underflow Reset  (Enabled)
#pragma config XINST = OFF       // Extended Instruction Set (Enabled)

// CONFIG1H
#pragma config CPUDIV = OSC1    // CPU System Clock Postscaler (No CPU system clock divide)
#pragma config CP0 = OFF        // Code Protect (Program memory is not code-protected)

// CONFIG2L
#pragma config OSC = ECPLL      // Oscillator (EC+PLL (CLKO-RA6), USB-EC+PLL)
#pragma config T1DIG = ON       // T1OSCEN Enforcement (Secondary Oscillator clock source may be selected)
#pragma config LPT1OSC = OFF    // Low-Power Timer1 Oscillator (High-power operation)
#pragma config FCMEN = ON       // Fail-Safe Clock Monitor (Enabled)
#pragma config IESO = ON        // Internal External Oscillator Switch Over Mode (Enabled)

// CONFIG2H
#pragma config WDTPS = 32768    // Watchdog Postscaler (1:32768)

// CONFIG3L
#pragma config DSWDTOSC = INTOSCREF// DSWDT Clock Select (DSWDT uses INTRC)
#pragma config RTCOSC = T1OSCREF// RTCC Clock Select (RTCC uses T1OSC/T1CKI)
#pragma config DSBOREN = ON     // Deep Sleep BOR (Enabled)
#pragma config DSWDTEN = ON     // Deep Sleep Watchdog Timer (Enabled)
#pragma config DSWDTPS = G2     // Deep Sleep Watchdog Postscaler (1:2,147,483,648 (25.7 days))

// CONFIG3H
#pragma config IOL1WAY = ON     // IOLOCK One-Way Set Enable bit (The IOLOCK bit (PPSCON<0>) can be set once)
#pragma config MSSP7B_EN = MSK7 // MSSP address masking (7 Bit address masking mode)

// CONFIG4L
#pragma config WPFP = PAGE_63   // Write/Erase Protect Page Start/End Location (Write Protect Program Flash Page 63)
#pragma config WPEND = PAGE_WPFP// Write/Erase Protect Region Select (valid when WPDIS = 0) (Page WPFP<5:0> through Configuration Words erase/write protected)
#pragma config WPCFG = OFF      // Write/Erase Protect Configuration Region (Configuration Words page not erase/write-protected)

// CONFIG4H
#pragma config WPDIS = OFF      // Write Protect Disable bit (WPFP<5:0>/WPEND region ignored)

        #include<p18F26J50.h>
        #include"delays.h"

                void main (void)

{

                    int x;

                    TRISC=0x00;
                    PORTCbits.RC2=1;
                    Delay10KTCYx(20);

                    WDTCONbits.REGSLP = 1;                                                          //PERIPHERAL INT DISABLE
                    OSCCONbits.IDLEN = 0;
                    INTCONbits.GIE=0;

                    PORTCbits.RC2=0;
                    DSCONHbits.DSEN=1;

                    Sleep();

                    x=0;

                while(1)
        {
         ;
        }

    }``


texts:
I have the receiver

which works when I wire a Hifi on the output. But when I try to send the signal to the port 2/3 of the following mixer

then I don't have any signal anymore. I guess I need to adapt the impedances (the receiver has a low output impedance while the mixer has a high entry impedance ?) ? How can I modify the circuit to do so ? Would someone have a good book for beginners explaining the basics on audio circuits please ? I always need tips like that


texts: How can a guy calculate the second collector current from this circuit?

texts:
This is an audio amp that we built for a project.

I can easily find the first collector current from the first transistor by multiplying it with its Beta(200) and since the first transistor is beta dependent.

on the other hand the collect current on the second stage (the current that actually matters) is not Beta dependent and changes as collector resistor value changes, here's proof:

Im stuck and can't figure out how to calculate it.
any help is greatly appreciated

ok so here's an update apparently the last stage is at saturation... which means Ic=Vcc/Rc... so for Rc=10ohms Ic=9V/10ohms=roughly 900mA and for Rc=100ohms Ic=9V/100ohms=roughly 90mA ...

what I just cant understand is when Rc=1ohms Ic is not 9A but is Ib*Beta=3.5A


texts:
I'm building a model rocket launcher with my son. The circuit is very simple as you can see. We want to add a buzzer and a LED/bulb when it is turned on as a warning to stay clear of the rocket.

How would I light the bulb and sound the buzzer without launching the rocket? The buzzer and bulb would need power before we press the launch button. We have purchased all the components we need I think and are ready to build.

simulate this circuit – Schematic created using CircuitLab


texts: What make now that I have implemented a working prototype of my system?

texts:
I developed code for an Arduino board (Arduino Uno + Ethernet Shield and some sensor) and I am thinking to try to make some money by selling the resulting system. Is it legally possible make that with Arduino? If so, what are next steps in order, for example, to assemble the system to a "compact box", "economize" things and start production?

In other words, what "I have" / "I should" make now that I have implemented a working prototype of my system?

Note: I am newbie in business related to electical matters.


texts:
Just kindly share what kind of input in the violet dot at center to inject so the red fault led would turn on?

When the GFCI no longer function, the red led lights up. I'd like to understand how the circuit detects it. Please focus on the one in blue. The one in red is the electronic reset button. The one in black is the original circuit in the datasheet. It is the same chip as the Fairchild RV4141A popularly used. http://datasheet.elcodis.com/pdf2/81/73/817329/rv4141a.pdf

See full circuit diagram at https://imageshack.com/a/img923/6796/7i3hHP.jpg

Here are the two solenoids. One to open contacts, one to close contacts, in the USA, the closing of contacts or Reset is mechanical hence no second solenoid.

When you remove the main diode, the red LED lights up. What kind of circuit in the blue section can do that?

(I have another open question, asking for help identifying unknown diodes and an SCR/transistor(?) shown in that schematic, so I can't mark their types on the schematic yet.)


texts:
What is the equivalent capacitance when a capacitor is connected in parallel with a conducting wire?

For example something like this circuit:

Suppose each capacitor has a capacitance 1 microfarad.We can easily notice the vertical axis of symmetry.Hence we can isolate the central junction.

I'm getting the equivalent capacitance of upper branch as as 3/8 microfarad using formula for capacitors in series i.e. 1/(1/1+1/1.5+1/1) microfarad .Therefore capacitance of the whole circuit is 3/8+3/8+0=3/4 microfarad.

However according to my textbook the answer is 2 microfarad.Where am I going wrong?


texts: Why supernode approch results wrong answer?

texts:
I have to find v1 using node voltage method could any one tell me what is the mistake so I am getting wrong answer i.e 78V but real answer which is given in book is 54V?

simulate this circuit – Schematic created using CircuitLab


texts: Can we verify gap energy of a material by applying voltage across it?

texts:
Regarding the following statement:

“A material with fully occupied or empty energy bands is then an insulator. This is the case when the gap energy exceeds ~9eV, because for such gaps.”

So my question is if we have an insulator and if we know its gap energy is 10eV; does that mean it starts conducting current when we apply voltage across its terminals above 10V?


texts: Pic-PC (Crossplatform) USB interfacing without writing custom drivers

texts:
I'm planning to use a PIC for a MIDI pedal that can be configured from a PC (through USB). Is there a way to do crossplatform (at least mac/windows, better if also linux) USB in userland (or another way to avoid the hassle of writing a device driver)? I know there's libUSB but I want to know if there's a better solution.

Microchip own drivers are windows-only, if I'm not wrong.
Thank you.


texts: What is the best method to compensating offset at the output of a peak detector circuit?

texts:
Brief of Application:

The signal conditioning circuit developed is used to detect or capture the peak values of dynamic systems such as the impulse tools. In this application, we use an impulse tool to tighten or loosen bolts and nuts, hence when the torque is applied to tighten or loosen the bolts at a set torque, my system should detect the peak torque applied to tightening the screws.

The Figure above shows the schematic of the circuit developed in Multisim i.e. An Instrumentation Amplifier followed by a Peak Detector.

Description of the Problem

The output across the capacitor goes as input to the TI-ADC1790. The problem is, the output at the peak detector has a small negative offset of -4.7 mV because of which some ADC counts are lost for the initial readings, since the ADC starts counting from the positive voltage scale. Hence, while testing I noticed that, when I apply the torque, the values are acquired only from the start of the positive scale. Therefore I need to compensate the negative offset to the ADC input.

Two ways I feel this can be done is by using an adder circuit at the output to switch the peak detector output to a positive scale or just use a voltage follower circuit while providing certain gain to amplifying the negative offset to a positive scale.

I am posting this question here, expecting to get a more appropriate solutions to this. Therefore, any help, suggestions or advice regarding this would be great. Thank you.


texts: Question regarding answer on "Stepper motor won’t turn once loaded"

texts:
I am trying to calculate the torque for the stepper motor I need in my system. I found out this question with a nice answer how to calculate the different parameters (Stepper motor won’t turn once loaded). However, looking in the nominal time for one step I found a contradiction.

From the provided formula one can conclude that decreasing the motor torque leads to smaller times. Also, having smaller moment of inertia leads to bigger times. Is that correct? In my understanding it is the oposite - smaller load should lead to faster times. I am asking that because in my system the moment of inertia is 0.00012 and I need to have nominal time for a step of about 0.01s. Trying to use the above equation leads to very strange values for torque.

Thank you


texts: Simple high-side load switch for grounded loads with linearization stage

texts:
I want to design a very simple high side switch, using components already present in the bill of materials of a larger project. I do not want to choose special components, but just try to re-use what I got, to simplify production and reduce related costs.
The switch needs to drive high-side a standard 3-wire Fan, one terminal being the (-), the other being (+) and the third one being tachometer signal. The Fan is rated 12V, 3.6W. The idea is to drive two fans in parallel with the same circuit.
The output voltage to the Fan needs to be linearized, since I want to be able to read the tachometer without any difficulties. The output voltage needs to be controlled by a micro in PWM, using 62,5 KHz carrier frequency, 5V logic.
Here's the simple circuit I have been working on:

simulate this circuit – Schematic created using CircuitLab

Do you see any flaws in this circuit?


texts: What's the name of this circuit, and how does it work?

texts:
I was reading Hack Into a Timer AC Socket and when I got to this paragraph:

  The design firstly have a RC buck? (not sure how to call correctly in English) circuit to step down the voltage from 220V AC to 5V AC, a 0.33uf safety capacitor (yellow one) used here, accompanying with a 1M discharge resistor. And after these two there is another current limited big resistor to prevent pulse and shock.

I was curious - I didn't even realize you could change AC voltage levels without a transformer (or at least not cheaper than with a transformer).

I understand that a resistor will lower voltage for a given current, but I would have expected AC mains to be too much power for a cheap resistor. And I don't get what the capacitor does - even if it is helpful here to get smoother DC power, wouldn't it interfere with anything else on the same AC line?

WARNING - ALL PARTS OF THIS CIRCUIT SHOULD BE CONSIDERED TO BE AT AC MAINS POTENTIAL AT ALL TIMES.

Capacitor C1 MUST be an "X RATED" capacitor specified by its manufacturer
for "across mains" use. NB NOT 'Y' rated.
Examples of X & Y rated capacitors


texts: LED lights wired in series will not light

texts:
I have a pack of simple LED lights that I planned on wiring in my boat for cabin lights.

I installed and wired them all in a simple series circuit.  Power supply connected to switch, switch connected to positive side of first LED and negative to positive of the remaining LEDs and so on, then connected to ground.

None of the lights will work.

When I test each individual light with a 12V source they work fine but when I wire 2 or more in series they will not pass voltage through the LED to light the next light.

What am I doing wrong?


texts: Simplest way to get regulated 12V from 10-18V input

texts: Getting a regulated 12V DC supply can be extremely simple with something like a LM7812. However, I am trying to get a regulated 12V output with a supply that can range from 10V to 18V. My thought is to regulate down to 9V and then back up using a step-up regulator. Is this the simplest solution available?


texts: Powering a Behringer MicroMIX MX400 - Car Audio Application

texts:
I am installing a car audio system that will have TWO aux inputs; one in the dash and one in the rear passanger seat are.

I decided to purchase the Behringer MicroMIX MX400 mixer. The power spec for the mixer is: 12v DC/150mA. It comes with a power supply that plugs into a wall outlet. I need to power it in a vehicle. Since it’s already 12V DC, I was thinking just connecting it to an unused/open circuit the interior fuse box that is 5A switched (only active when key is in the ignition). The power will be connected to the fuse box circuit and I’ll just ground it to an exiting ground point.

Will that work?


texts: The above is an excerpt from the book "Crystal Oscillator Circuits". It said it is meaningless to measure voltage across a crystal. I can not understand why. When crystal is operating in parallel resonance region, it appears inductive. And everyday voltmeter can not calculate $$\frac {dI}{dt}$$ Which is necessary to calculate the voltage across inductor. Is this the reason why the excerpt above claimed that it is meaningless to calculate voltage across a crystal?


texts:
Today about my first components in an electronic store. I'm currently making a MIDI IN circuit for my Raspberry PI.

My local shop didn't have male to male DIN 5 pin cables, as they seem to be obsolete, just like MIDI, and thought I'd buy a male to female cable, and cut the female connection and connect the needed cables to my breadboard manually.

This seems like a good plan, except for the fact that I have no clue which color represents which pin on the DIN 5 cable, and the Internet, for once, has given me no answer until now.

I need to find pins 4 and 5 in the cable.

I currently have

Blue
Green
Black (possibly pin 2)
White
Reddish

If needed I can attach a photograph, but there really isn't much more to it than this.

Which pin is represented by which color?

EDIT: Currently checking for continuity manually with a multimeter.


texts:
For the picture below, the answer for Voc is 7.5V, but when I add an Isc at terminals AB, and use KCL, I get Voc = 3.75V.

Here are my steps/equations:

(1) 15 = 4I1 - 2Isc

(2) 0 = 3Isc - 2I1

I get Isc = 15/4A, which is the same is Voc (15/4) or 1K*Isc.


texts: suppose I want to keep an Arduino powered during the night, and recharge it during the day with a solar cell. What kind of circuit do I have to make, how many and which type of batteries, and what size of solar panel do I need to keep it going?


texts: Why do we not consider Thevenin Voltage source while dealing with Dependent sources in RLC circuits?

texts:
"If no controlling current or voltage associated with the dependent source is of interest, we may simply find the Thévenin equivalent connected to the inductor and capacitor."

This is what's written in Engineering Circuit Analysis- Hyatt, Kimberly.

After doing a question this way, I found it a little strange:
We're finding the Thevenin Equivalent which includes an independent voltage(Thevenin) source and a Thevenin Resistance, and the total circuit consists of the capacitor and inductor as well. Since it includes an independent voltage source the total response should be the sum of the natural and the forced response, but we're not including the forced response in it. Why so?


texts: step response of a circuit having an inductor loop

texts:
What is the step response of \$I_1(t)\$ in the following circuit? (I mean if we apply step as input I what will be the I1?

I simply used Laplace transform and calculated the step response, but it was wrong according to the book I'm reading. It says in this circuit the current is not continuous at t=0 because we have a inductor loop, which I don't understand.

simulate this circuit – Schematic created using CircuitLab


texts: Practicality of using flat-spiral coil as electromagnet?

texts:
For my project, I'm using a 3D magnetic sensor to track the proximity of a local electromagnet at any time, no more than a finger length away.

Ideally, I would like the the electromagnet to be:

between 5-10mm radius
flat, with a height below < 5mm, lower the better
be able to produce a magnetic field strong enough that my 3D magnetic sensor (BNO055) can pick up within range of 5-7cm.

Something like this, but assuming my qualifications:

With this in consideration, is this possible or practical having an electromagnet this small and powerful enough to produce the necessary field?

Bad question, but from what I've researched, an inductor is an essentially a single coil wrapped around a core, so it is by definition an electromagnet when a current passes through it. That being said I've looked online attempting to find one to buy, and I've come across strikingly different looking inductors, making me question if I actually understand what an inductor is. This fixed inductor is the same as the image above (besides being axial, radial, or ..etc) and both will produce a magnetic field when a current is passed through?

If I'm missing something altogether or if anyone has any recommendations related or otherwise please comment, I appreciate any feedback.


texts: Output impedance of a 4mA to 20mA current loop

texts:
I have the most basic of basicness circuit. The implementation is a XTR115UA IC with a 40µA - 200µA input (based on sensor voltage) which is amplified to the desired 4mA to 20mA current in the current loop.

I have been given the task to calculate / measure the output impedance of this current loop. The output impedance should be below 0.1 Ohms, but I don't see anything that gets me even close.

Hope you can help.


texts: How to break this multistage feedback amplifier to find loop gain Aβ ? (I'm using pspice)

texts: by hand calculation I know that loop gain Aβ of this (current-current) circuit is 30, I tried to break this circuit and add Vtest to it , and setting input to zero but I didn't get a result that match my calculated result


texts:
I am looking for an example of a video genlock pixel clock generate using a PLL synchronized to the video sync signals. Such things seem to be rather rare now as everything has moved to highly integrated parts designed for LCD displays.

My goal is to do a video overlay. To stop it juddering the clock of the microcontroller generating the overlay needs to be synchronized to the video clock. I found the AV9173 (or ICS9173 clone), which while not widely available does appear to do what I want. Unfortunately the datasheet is rather sparse (http://media.digikey.com/pdf/Data%20Sheets/IDT/AV9173-01.pdf) and refers to an "Application Brief (AB01)" which I can't find anywhere.

I found a solution in the EL4584/5, which offer various PLL locked pixel clocks and are somewhat available.


texts: Simple methods for synthesizing circuits

texts:
I'm studying systems engineering and I am currently attending a course in computer architecture. In our career, we don't have much training in regard to hardware, so we find very hard to synthesize circuits.

In particular, we only have to synthesize arithmetic circuits (in previous courses we saw things like implementation of ROM's, complex control units and models based on automata).

For example, some exercises ask us something like:

  Perform a sequential 8-bit binary adder (time iteration). To
  implement, use only shift registers, flip-flops and:

  a 1-bit full adder.
  a 2-bit full adder.
  a full adder of 4 bits.

So, my question is: What should I do to implement things like this?, Are there simple ways to find the disposition of records and its connections to the adder?

Finally, do you know some material for reading and be able to perform these kind exercises?


texts: What's a fun electronics related gift for 2012?

texts: My cousin's 19-year old son has a birthday coming up and he is quite intelligent with computers, software and electronics. What's a fun / serious electronics-related gift I could buy him? Anything from robotic kits to electronic development platforms accepted as ideas. Ideally something with a serious use-case also, so its not simply a toy you use and throw.


texts: How MOSFET gate capacitances (Cgs, Cgd) are calculated?

texts:
I have read somewhere that the gate capacitance (Cgs, Cgd) of a MOS is calculated as below:

Strong inversion:

  Cgs=(2/3)Cox.W.L + Cov

Non-saturated:

  Cgs=Cgd=(1/2)Cox.W.L + Cov

where Cov is overlap capacitance.

Could anyone explain where do the formulas come from?

I couldn't find a link that explains that now.


texts: How far should a TEC1-12706 peltier module be away from the heat source to prevent damage when using it to generate thermoelectricity?

texts: I am working on my science fair project and only have 5 peliter modules. In order to build my project I need to know how far it must be to keep from being damaged because I can not replace these once I have begun.


texts: How to wire a 12V DC fan to a Molex connection?

texts:
I have a 12V DC fan with two wires (black and red). I want to solder it to a Molex 8981 connection (powered by an ATX power supply).

Here are the details for the connection:

I'm guessing the fan's positive red wire goes to the +12V yellow wire, but I'm not sure what to connect the black wire to.


texts: Arduino: why does simple include not work

texts:
Hello in my arduino code i simple want to include another file like this:

#include "letters.h"

but it says

 error: letters.h: No such file or directory

the letters.h is definitely there, right next to the ino file from which i compile.


texts:
This is not directly electrical, but I am working on making a real life version of a coin block from Mario. Basically I use an LDR and to detect if someone punches the block and then use a transistor to turn on a DC motor.

The problem is that I want to be able to 'shoot' a coin up from the box using the motor, but I am not sure how I could achieve this. I have tried attaching some objects to the motor, which then hits a stationary coin, but that isn't very effective.

In summary, I want to be able to use a motor to shoot a coin up against gravity,


texts: How to avoid lag of servo motor used with distance sensor in FRDM-KL25Z

texts:
I am having trouble with using distance sensor and servo motor at the same time. My project is a radar project. I have a servo motor sweeping around and on top of it I have distance sensor. When I compile and run this code, servo motor lags and does not sweep smoothly like it did without distance sensor. What can I do to avoid lag?

int main() {
    while(1) {
        runServo120();
    }
}

long echo_duration() { //used for distance sensor
    timer.reset();
    trig = 0;
    wait_us(2);
    trig = 1;
    wait_us(10);
    trig = 0;
    while(echo == 0);
    timer.start();
    while(echo == 1);
    timer.stop();
    return timer.read_us();
}

long distance(){ // used for distance sensor
    long duration = echo_duration();
    if(duration > 30000)
        return -1;
    long distacne_cm = duration /29 / 2 ;

    return distacne_cm;
}

void runServo120(){ //sweeps 120 degree and calls distance() function
    float angle = 0.00115;
    for(int i = 0 ; i<50; i++){ //going forward

        anglePin = 1;
        wait(angle);
        anglePin = 0;
        wait(0.02-angle);
        angle = angle + 0.000014;

        if((int)distance() < 30){
            myled = 0;
        }else{
            myled = 1;
        }
    }
    angle = 0.00185;
    for(int i = 0 ; i<50; i++){ //going backward

        anglePin = 1;
        wait(angle);
        anglePin = 0;
        wait(0.02-angle);
        angle = angle - 0.000014;

        if((int)distance() < 30){
            myled = 0;
        }else{
            myled = 1;
        }
    }

}


texts: Can I use a dead Weller soldering station?

texts:
I have only the pencil of a Weller soldering station

Can I use it without the station? I tried to use it directly with 220V but it's not working.

In the pencil it says 50W/24V. I tried with 32V but nothing happened.

Do you have a solution?


texts: Could OLED displays be made to produce a voltage when off?

texts:
According to this guy it is feasible to use LEDs to detect light, because they will turn any light emitted on them into a tiny voltage that can be used in a sensor.

Since modern flat screens (OLD) found in some mobile phones and TV sets are basically just big arrays of organically grown LEDs, would it be feasible to produce power from light when they are switched off, effectively turning them into solar panels?

EDIT: I clarified the question to mean OLED based displays. Backlit displays is not what I had in mind.


texts: Design Considerations for Electronics in Space

texts:
What additional constraints do we face when designing electronics/microsystems for use in orbit?

What kinds of shielding techniques are employed? Is it common to enclose all electronics in a faraday cage, or are other shielding methods preferred?

How are aerospace grade components tested, and how does their reliability stack up against 'off-the-shelf' parts? Can properly shielded standard components compete from a reliability standpoint?

What types of mechanical support/bracing/damping are used to protect electrical systems during take-off/landing and for the high thermal stress expected?


texts:
My hardware design team have given me circuit to measure current  consumed by load.I have to measure current consumed by Load using MCU ADC. Can someone explain what exactly this OP amp is doing ?

I am from software side & not a hardware expert.


texts: Relay alternatives that are silent and support 500mA+

texts:
What can I use as a silent "general-purpose" relay alternative?

There are various scenarios where I will need a relay-like device that allows me to control one circuit with a separate isolated circuit.
I have 3.3-5V microcontrollers and I want to use them to control, say...

A 12V DC 1A circuit (large-ish current)
A button on a radio (low-voltage and current)
A 24V AC circuit

A simple 5V magnetic relay+diode+transistor would work for nearly any situation (and no calculations necessary), but they are too loud.
I see two alternatives: Optocouplers and solid state relays. Unfortunately, most of them seem to have a maximum output of around 50mA (I generally need 500mA or more). They are also harder to find and more expensive. Finally, they are not a simple coil and contact setup, and there is much less documentation on how to implement them with a microcontroller.

Are optocouplers and solid state relays the best solution? I'm looking at these:
http://www.mouser.com/ds/2/149/FOD3150-95595.pdf
http://www.mouser.com/ds/2/427/vo14642a-279692.pdf
http://www.toshiba-components.com/docs/opto/TLP152_en_datasheet.pdf


texts: Is it possible to comment out a circuit in LTSpice?

texts:
Is it possible to "comment out" a circuit in LTSpice in the same way that it is possible to "comment out" a directive? Such that it is visible, but ignored during simulation.

Example use cases:

file with multiple subcircuits of which only some you want to simulate
circuit with undefined component values to be used as a quick reference (schematic)


texts:
I am trying to design a switching regulator for LEDs, which uses the LM3405 as controller. This IC uses the BOOST pin to power the internal MOSFET driver, which controls an internal MOSFET. There are few ways to derive this voltage, and in particular the proper way that I need is to derive this voltage from the output voltage.
Here the circuit:

But I don't undesrtand how the gate driver can actually start at the beginning, while there is no output voltage. Maybe I miss something...

Here the basic schematic of the IC internal blocks:

Thanks


texts: Trouble getting I2C working on STM32 (stm32f103c8t6)

texts:
I'm starting out with I2C. I have a development board with stm32f103c8t6 to which I have connected GY-68 board with BMP180 barometric pressure sensor. Documentation of BMP180 describes Chip-id register [0xD0] which holds a constant value of [0x55] and can be a good way of testing if the I2C communication is working.

I am trying to read this register, but my code does not work. I am not sure if my setup is correct, because neither the BMP180 address nor register addres seem to be transmitted.

The board has an external clock set to 8MHz which I am confident is setup properly, because I have working UART which I use to check if the registers are set.

I have calculated CCR and TRISE with this instructions

void initI2C()
{
RCC->APB1ENR |= RCC_APB1ENR_I2C1EN | RCC_APB2ENR_IOPAEN;
GPIOB->CRL |= (1 << 31);// Set pin B7(SDA) to alternate out open drain max 10MHz
GPIOB->CRL |= (1 << 30);
GPIOB->CRL &= ~(1 << 29);
GPIOB->CRL |= (1 << 28);

GPIOB->CRL |= (1 << 27);// Set pin B6(SCL) to alternate push pull max 10MHz
GPIOB->CRL &= ~(1 << 26);// I have also tried open drain
GPIOB->CRL &= ~(1 << 25);
GPIOB->CRL |= (1 << 24);
I2C1->CR2 |= 0x08;       // Set clock to 8MHz
I2C1->CCR = 0x28;        // Set CCR
I2C1->CCR &= ~(1 << 15); // Sm Mode
I2C1->CCR &= ~(1 << 14); // Duty cycle for Fm mode
I2C1->TRISE = 0x09;      // Set clock rise time
I2C1->CR1 |= 1;          // Enable peripheral
I2C1->CR1 |= (1 << 8);   // Set start bit
while (!(I2C1->SR1 &= 1)) // Wait for start condition generated
{} //Never passes
I2C1->OAR1 = 0xEE; // Set Address
I2C1->DR = 0xD0; // Set address of id register
while (!(I2C1->SR1 &= (1 << 1))) // Wait for end of address transmission
{} // Never passes even with above while commented
while (!(I2C1->SR1 &= (1 << 6))) // Wait for data register not empty
{} // Never passes even with all above while commented
}

Now I know I don't read the register value here, but the the start condition never is generated, the address is never transmitted and the data register is not transmitted. I am reading some activity on both SDA and SCL pins with my multimeter, but I don't have oscilloscope to check exactly.

Any help would be appreciated.


texts:
While looking through some Verilog code, I came across this:

input [7:0] data [0:16]

The code referred to this as memory.

Could someone explain what it does? I have only dealt with single dimensional arrays before (only one [])

I'm assuming it has something to do with SRAM, but as far as I know SRAM memory is allocated using altsyncram

So what does it do? Thank you.


texts:
I'm building a DCC booster that at present uses one LMD18200 as per the circuit diagram. This gives me a continuous current draw of 3A, however I'd ideally like much more amperage (since I'm running a number of model trains with this at once, and it's not unusual for the older motors to draw well over 500mA under load, plus lights and smoke generators.. it adds up quickly.)

Usually I'd just look for a more powerful HBridge, but in this case I need relatively fast rise and fall times to remain within DCC spec - something I haven't been able to find elsewhere in a more powerful HBridge. The rise time with 1 LMD18200, with appropriate caps is around 100ns which is well within the DCC spec of 500ns - so it doesn't matter if this suffers a bit, as long as it doesn't get pushed beyond 500.

At present my knowledge is nothing more than some HBridges can be paired up in parallel safely and others can't because one will likely take the vast majority of the load and end up burning out anyway - so is an LMD18200 safe in this respect? Just as importantly, will the rise / fall times suffer beyond the spec? And if this feasible, what route would you recommend taking?


texts: How to implement \$V_0 = 5V_1 - 3V_2 \$ using one Op Amp?

texts:
How to implement  \$V_0 = 5V_1 - 3V_2 \$  using one op-amp?

I have tried to use the differential amplifier techniques but came to no avail.


texts:
I need to add encoders to the 4 motors attached to a "remote" PCB.  The remote PCB in question does not have microcontroller on it, but rather is connected to the microcontroller PCB with an I2C connection (yes, using a differential I2C amplifier).  Because of limitations in the cabling I only have the I2C connection between these PCBs.

So, I need to read 4x quadrature encoders over I2C.  Some options and their associated issues:

Read encoders with microcontroller using interrupts.  This seems to be the most common method.  However, I don't have a microcontroller on the remote PCB, so this doesn't work.
Use a Quadrature decoder chip like the LS7266R1, LS7267 or other dedicated chip.  However, these chips don't seem to be available on any vendor on Octopart, and they are expensive and they don't have an I2C interface.
Build a quadrature decoder out of a D flip-flop and a counter and connect to an I2C IO expander:  There seem to be a ton design issues with the build it myself approach:  More flip-flops and NAND gates are needed to get full quadrature resolution and counter stability, counters on digikey only come in 4-bit and 8-bit versions (why are 8-bit counters rare and >$10 each?), ... all of this adds up to more cost and complexity than just adding a microcontroller.

Is adding a microcontroller to my remote PCB the best way?  Why isn't there an easier way to do this?  Given the number of digital encoders in the world, I'm surprised there isn't more available.


texts:
I'm not an electrical expert and lately, I ran into a problem using PWM for steady control of a heating rod.

Let's assume there is a set value (Temp in C) for the heating rod. I'm currently using a PID controller to output certain % at the end of the PID loop. This valve is used to feed to the PWM to generate necessary PWM signals.

The problem is once the actual temperature almost reaches the range of set temperature. The switching ON/OFF occurs very often in order to keep to the Set temperature.

Moe often switching causes to reduce the lifetime of the hardware. And replacement of hardware is out of option. Hence, I'm forced to think of an alternative logic for better control of the temperature.

The 2-point controller is something easier however, it is observed that there are a lot of deviations from the setpoint.

P.S: There is a delay of 5 seconds between two switches (some hardware related restrictions). Hence the turning ON of Turning OFF pulse can't be less than 5 seconds.

I really appreciate your ideas or suggestions on some simple strategy where I can reduce the number of switching and at the same time have better control over the temperature.

OR

Is it a trade-off one has to choose between better control and less switching(in the end lifetime of switches)?


texts:
The observability matrix formula is present in two forms in textbooks. My question is about which one to use.

the first one:

the second one:

Now when applying both on the same system, I get different results:

first formula:

second formula:

edit:i need the observability matrix to preform transformation of the state space equation to a Observable canonical form


texts:
I am building a PFC using a TI C2000, this is for a final project and currently reading lots of datasheets on the subject.  I have a question regarding a calculation used on a On Semiconductor Application Note AND9062/D, full PDF is here.  This gives some calculations and steps for the inductor sizing as well as losses due to the mosfet and recovery diode.

The extract I am having trouble with is regarding the use of the below formulae in equation 4, which uses the SQRT(6).  Why SQRT(6)?

Regards,

Ant