texts:
When I short the negative and positive wires on my DC lab power supply, at ~1V the supply shows it's max current output of 5A. but when I turn down the voltage, at some point the output ampere decreases.

I was wondering, if there is a physical limit, which affects the maximum amount of ampere that can flow on low voltage or if this is just from my power supply?

What I also recognized, was that if I put a resistor in between the contacts, the current seems to drop much earlier while decreasing the voltage. So I tought, that the resistance might affect this effect?


texts: Unknown component in an electronic dictionary

texts:
I'm exploring the inside of my favorite device, a Japanese electronic dictionary. It runs on AAA batteries and has two screens (one for writing and one for viewing), speakers/headphone jack, a USB connector and an SD card slot.
There's a peculiar component I can't identify. It looks like two plates of metal glued together with a lead from each plate. The simplicity of it makes me think it's a capacitor; however, I've never encountered a capacitor that looks like this, and the huge footprint seems like a waste for a simple capacitor.
Here's a picture of the side of the PCB with the unidentified component. The leads on the top left lead to a keyboard PCB and on the ones on the right lead to the screen. The unidentified component is below the two blobs.

Here's a closeup of the component:

In case it helps (or is interesting!), here's the other side of the PCB:


texts: Link integrity test pulse vs carrier signal

texts:
Ethernet uses a refinement of ALOHA, known as Carrier Sense Multiple Access (CSMA), which improves performance when there is a higher medium utilisation. When a NIC has data to transmit, the NIC first listens to the cable (using a transceiver) to see if a carrier (signal) is being transmitted by another node. This may be achieved by monitoring whether a current is flowing in the cable (each bit corresponds to 18-20 milliAmps (mA)). The individual bits are sent by encoding them with a 10 (or 100 MHz for Fast Ethernet) clock using Manchester encoding. Data is only sent when no carrier is observed (i.e. no current present) and the physical medium is therefore idle. Any NIC which does not need to transmit, listens to see if other NICs have started to transmit information to it.

Reference 1

I am getting confused about CSMA/CD (half-duplex communication) after reading below sentence.

  Data is only sent when no carrier is observed (i.e. no current present) and the physical medium is therefore idle.

Is not pulse (link integrity test pulse, normal pulse, fast pulse) is generated when the medium is idle?

One more thing.

  In the output from the show interfaces fastethernet , show interfaces gigabitethernet or show interfaces tengigabitethernet command observe the value of the carrier signal counters. The lost carrier counter shows the number of times that the carrier was lost during transmission. The no carrier counter shows the number of times that the carrier was not present during transmission.

Reference 2

Is carrier lost determined by RX of interface?


texts: MOSFET to connect two batteries in series

texts:
I am designing a small bidirectional circuit consisting of two batteries in series as a power source. Part of the circuit will be a charger, to charge the batteries when they are not in use, which is triggered by external circuitry.

The problem I am having is that each battery has its own charging circuit, therefore I think that the must be disconnected from each other in order to facilitate charging.

I had the idea of using a MOSFET which joins the positive of one battery to the negative of the other battery when the circuit is discharging, and then disconnect the two when it is charging. But I am having difficulty implementing this. I have tried simple simulation with PSPICE using only voltage sources however I could not get it to work. Is this possible? If so how can I do it?


texts: Which logic gate family is used in a PC? TTL or CMOS?

texts: I read that the propagation delay of CMOS logic gate is longer than TTL; therefore they are not used where speed of processing is important. I thought computers or computer cpu is using CMOS. According to the text I read it says CMOS is not used in computers. Is that true?


texts:
Microcontroller datasheet

I am in the process of selecting a micro controller for a project where I need a lot of PWM pins (around 30) for LEDs. I'd prefer hardware supported PWM so that my CPU is free for other tasks but it's not a necessity if it can be done comfortably on software side as well. 100 Hz PWM frequency should work for the LEDs and I won't be needing more than 8 brightness levels.

I have narrowed down on STM32F072V8T6 (100 pin LQFP) which has 87 GPIO and other features (like capacitive touch sensing and rtc with Vbat pin) that I require for my project.

Going through the datasheet, I am not able to figure out how many PWM pins can I get out of it (I come from arduino background where no. of PWM pins are mentioned directly). I found a small note saying - "One 16-bit advanced-control timer for six-channel PWM output"

Does that mean I can have only 6 PWM pins?

If this is the really the case, what are my other cheap alternatives to get as many PWM outputs? I saw some PWM output port expanders which communicate over i2c but the cost seems too high.


texts:
Evening Guys,

The amplifier shown below is clipping before the rails of my supply. I have narrowed the issue down to the Darlington pair before the Emitter Follower output stage and provided the PSpice output waveform. The goal of the project is to utilize a class A output stage so please don't suggest changing the output stage to B, AB, or D. Please help me allow the output to swing to approximately (+-15V).

For your convince here is the data sheet for the BC550 transistor.

BC550: https://www.fairchildsemi.com/datasheets/BC/BC547.pdf

Lastly in case you would like the Cadence project or larger images, here is an FTP link:

ftp://ftpAdmin:Aa1@67.240.161.199:21/EE%20Stack%20Exchange/BC550%20Darlington%20Saturating/

I sincerely appreciate the help I receive here,

-Ryan Selby


texts: How do you determine if a chip has either hold or setup violation after it has been manufactured?

texts: Suppose a chip was taped out without proper timing analysis. After you get the chip back, what kind of testing is done to check if there are any setup or hold violations in the chip?


texts:
I have this buck converter - BD9G201EFJ-M

Buck converter specifications:

Input voltage - 18V to 32V
Switching frequency - 300kHz
Output voltage 9V
Load current - 0mA to 200mA maximum.

I am performing a test where in, I disconnect the input voltage using this toggle switch and measure how long the output 47uF capacitor takes to discharge the output 9V. I performed this test with different input voltages (18V, 28V & 32V) and different load currents (no load, 50mA, 100mA & 200mA) at 25degrees celsius and the results were normal and as expected at 25degrees celsius..
Toggle Switch :

When I perform the same test at 85degrees celsius, for 18V input voltage and 28V input voltage, the output is as expected. When I keep the input voltage as 32V at +85degC with no load connected at the output, my IC burns out but (smoke came) and for a brief moment, the output was same as the input voltage of 32V.
I took out the IC and measured continuity between Vcc and LX pins of the IC, and the multimeter showed continuity. So, there is a short between Vcc and LX pins.
My hypothesis:
I think due to the high input dV/dt (dV - 32V to 0V & dt in the order of 100ms) at the input, I think the internal MOSFET between the Vcc and LX pins got damaged and that's why we are getting a short between those 2 pins.

My Questions :

Why is the test giving proper results at +25degrees celsius but failing at +85degrees celsius?

Is high dV/dt the problem? If so what actually happens when we give high dV/dt to the drain of the MOSFET while the Gate is turned ON (N-MOS)

Sample waveform @ +85degC with NO LOAD:
For an input voltage of 18V, I get the below waveform with no load connected at the output :


texts: Two voltage regulators in series vs in parallel

texts: What is a better idea - to connect two voltage regulators in series or in parallel? I don't need much current (max 300-400mA). I need both voltages. Transformer output is about 9V. U2 gives 1A max and U3 800mA max.


texts: Finding value of resistor between two diodes

texts:
I'm using an Arduino and I have the following circuit:

I couldn't find the symbol for analog signal, so the voltmeter represents a connection to the Arduino's analog input pin.

How can I work out R1? I have used voltage divider, but it doesn't take into account the voltage drop over the two diodes (which I believe is 500millivolts each).

Thanks!


texts: Timebase effect on measuring ripple on SMPS

texts:
hey everyone i get straight to  the point, look at these two pics below are we losing anything in the peak-peak measurement when using 5us instead of 5ms?(they are two different units)
if yes by mow much?

(5ms)

(5us)

does using lower timebase "hide" any specific frequency?(some one told me the 5us one hide`s mains 50-60hz ripple effect on the output therefore the pk-pk value is smaller on 5us one than what it should be)
note:
probes was connected directly to the load tester on both test and the main ac input is  ~2200v@50hz.....+ scope bandwidth was set at 20mhz on both tests..
my main question  is that how much these two measurement are comparable...


texts: PCB Assembly Costing Help - Software tools out there?

texts:
Are there software solutions out there that help provide a cost estimate for PCB assembly? I have a BOM and want to generate a cost estimate to help me negotiate with my suppliers better.

I also want to understand the costs of my PCB assembly earlier in the design phase so I can meet my target costs.

I have been using home grown spreadsheets to estimate these costs but it is tedious and time consuming. Are there any tools out there to help automate this? Application is high/medium volumes for machinery and aerospace.


texts: Why does my 74AC04 not invert my 14.31818 MHz frequency?

texts:
I have a crystal oscillator (full can) running at 14.31818 MHz.  When I put that on my scope, it shows about 14.3~ MHz.  My scope is a Rigol DS1102E 100 MHz so I understand that you need about 10x the frequency of what you're measuring so I would need about 140+ MHz scope to accurately see the 14.31818 MHz frequency.  So I get that.  Anyway, oscillator seems to be working.

Next, I wanted to "square out" the wave a little by running it through a SN74AC04 HEX inverter.  So when I tie the output of my oscillator to A0 I get nothing but a flat line on O0.

So thinking maybe the '04 was bad, I swapped it out.  Same thing.

Next, I decided to back down the frequency.  So I plugged in my SIGLENT SDG805 waveform generator into A0 (I unplugged the oscillator).

I then tried different frequencies.  Starting at 1 KHz all the way up to 5 MHz (the maximum I can generate with the SIGLENT).  The scope shows a very nice square wave for the most part.  5 MHz is a little off but the scope shows pretty much the same thing as if I had a 5 MHz crystal.

Anyway, why does the 14 MHz oscillator show a flat line?  The specs of the '04 say (from what I understand) that it should be able to handle that frequency.

I'm running everything at 3.3v.

The specs say tPLH and tPHL at 3.3v should be about 10ns and 9.5ns respectively.  10ns should allow 100 transitions per micro-second right?

So wouldn't I get around 6-7 transitions at 14 MHz?

Anyway, what am I doing wrong?

Thanks!


texts:
This article  gives 2 main disadvantages:

Variable frequency
Requires ESR on the output cap

Is variable frequency a big of a deal? Why would synchronization matters for a converter?
And why are high ESR necessary for it to work? What I'm missing here?

I ask this because  I've been working on a boost converter with hysteresis control as a Uni project, and I've found very little resources or interest - giving me the impression that either the solution is known and considered bad, or that is unknown but not worthy of research.

Is Hysteresis control undesirable? What makes it so?


texts:
I want to use a LF33 voltage regulator to power a nRF24L01 module from a Arduino Pro Mini.

I plan to power the Pro Mini with a 9V battery, then use it's 5V internal regulator to power the LF33 which drops the voltage to the 3.3V required by the nRF24L01 module.

The LF33 datasheet says it needs 0.1uF IN cap and a 2.2uF OUT cap.
My question is: Can I use bigger caps or do they have to be exactly that?

Or is this even the right way to go about things? Would it be better to go from 9V to 3.3V directly? I was hoping to spread the load and heat on both regulators like this, am I wrong?


texts: Help with electronic circuit for a bracelet that reads state from rfid tag attached to it and lights up the corresponding LED

texts:
I'd like to make a bracelet which has an RFID tag and LEDs inside of it. I made a device
(using Arduino and rc522) that will categorise people's bracelets into one of 3 categories when it touches the RFID tag on the bracelet and writes that category(i.e 2). I want the bracelet to be able to read the category from the tag and light up the RGB LED to the corresponding colour(i.e light up green when priority is 1).
I tried some stuff with adafruit st25dv16 but I think rc522 isn't compatible. Could someone please help me figure this out. Maybe I can use attiny in it somehow? I'd like the bracelet to be relatively small and low power. Thank you.


texts: Power supply for dirvers in 3-phase motors - multiple transfromer windings

texts:
Looking into 3-phase motor drivers, especially ones for IGBT hex modules for motor drivers, I have noticed the use of transformer windings is arranged so that there is a separate winding for each of the 3 high side FETs/IGBTS/other electronic switch, but only one winding shared between all three of the low side FETs/IGBTs/switches.

As an example, Texas Instruments has a IGBT driver for 3-phase inverter, such as this one: http://www.ti.com/lit/ug/tidu670a/tidu670a.pdf

While I understand that an isolated supply is required as the supply rails being switched may have nothing to do with the power supply for the driver, why is there this arrangement of seperate windings for each high side, then one for all of the low side switches? In the datasheet linked in my question, the high side coils each supply 100mA, while the low side coil gives 300mA, so it isn't power consumption.

The only reason I know of is isolation, but why can the low side get away with only one coil: low side shares the same ground rail, but the high side share the same power rail. Or am I missing something here?


texts:
I'm not sure how to do this. I have this LED - the 4 pin 3W RGB led.
I want to be able to control it using an Arduino (ideally I would control 4 - 6 LEDs.) By controlling I mean not only control the color but also turning it on and off.


texts: Is it possible to toggle a monostable 555 circuit?

texts:
I've got a typical monostable 555 circuit, with a long pulse, set up pretty much exactly like this:

However, I want to be able to use this circuit in a way that the trigger switch can also shut off the output immediately, before the pulse would normally end, and preferably using the same button for initiating the pulse as well as ending it. I know that it's possible to use a 555 to make a toggle button, is it also possible to easily combine these functionalities?


texts:
This is my first time knowing what rs-485 is and I am computing the power consumption between only two (2) rs-485 transceivers SN65C1167. As I read the datasheet, i became confused on the term "load" because i am looking for their current consumption to solve for power. Image below will make you understand in short what i don't understand fully.

upon researching what is load, i bump into this image below.

and reading this article about rs-485 by TI calculating "UNIT LOAD". Is the Load referred on datasheets saying "NO LOAD" means "NO UNIT LOAD"?


texts: GaAs p-type vs Si n-type Mosfet frequency

texts: Witch of the above can be perform at highest frequency. Lets assume the 2 devices has the same size and voltage rating. I assume that the speed is a function of electrons mobility on the n-type and the holes mobility on the p-type but i cant figure out how the frequency can be calculated.


texts: Contradiction while using the convolution sum for a non-LTI system

texts:
In a recent quiz, we were given the following problem:

  The cascaded LTI systems \$\mathcal{T}_1\$ and \$\mathcal{T}_2\$ respectively have impulse responses \$h_1 \lbrack n \rbrack = \delta\lbrack n + 3\rbrack\$ and \$h_2\lbrack n \rbrack = \delta\lbrack 5 − n\rbrack\$. What is the output when the input is \$x\lbrack n \rbrack = n\$, i.e., find \$y \lbrack n \rbrack = \mathcal{T}_2 \{ \mathcal{T}_1 \{ x \lbrack n \rbrack\}\}\$.

I am primarily confused about the "LTI-ness" of the system and at a contradiction; given the second stage to be LTI (assuming that for a system to be LTI as a whole, all its stages/subsystems must also be LTI). Thus, we can say that a sub-system with  \$h \lbrack n \rbrack = \delta \lbrack 5 - n\rbrack\$, i.e. \$y \lbrack n \rbrack = x \lbrack 5 - n\rbrack\$ should be LTI, which already seems to be false. To prove that, I considered the following convolution sum: $$\tilde{y} \lbrack n \rbrack = \displaystyle{\sum_{k = -\infty}^{\infty} x \lbrack k \rbrack \delta \lbrack 5 - n + k \rbrack} = x \lbrack n-5 \rbrack \ne x \lbrack 5-n \rbrack = y \lbrack n \rbrack$$

And this is a contradiction since, after the convolution, the output doesn't match the original output with which we started.

So, in summary, I have the following two doubts:

Is the convolution sum only true for the output relation of an LTI system? If so, then can it be used to prove non-LTI-ness of a system in the same manner as above?
Is the quiz question incorrect?

Any help will be greatly appreciated!

EDIT:
While answering @jramsay's comments, I realized that interestingly, the convolution always gives a result that corresponds to an LTI system (as in the case above too: \$y[n]=x[n−5]\$ is LTI whereas \$y[n] = x[5-n]\$ is not).

Also, since \$\delta[n]\$ is even, any non-LTI system's impulse response, for example, \$\delta[1−n]\$, will equal \$\delta[n−1]\$ which corresponds the impulse response of an LTI system. This explains why I am getting LTI characteristics after the convolution. This is interesting too since in either way the impulse response implies delaying the signal by 1 (in the current example).

And so did the impulse response \$\delta[5-n]\$ stated in the quiz question just qualitatively imply a delay of 5, and, technically, not the exact description of the underlying system?


texts:
I've got this circuit. It contains a switch that will open at T = 0:

I'm tasked with finding the voltage on the capacitor. I calculate the initial conditions (assuming that the capacitor and the inductor are fully charged). The initial C voltage is 16 V and the initial current through the inductor is 0 A.

Then I proceed to simplify the remaining components and I get to this circuit:

simulate this circuit – Schematic created using CircuitLab

Then I want to apply Kirchoff's Voltage Law. I get this equation:

And solving for the ODE (without the constants):

However, according to the solution manual, this equation describes the voltage in this circuit. How can that be? I can't understand the gap between having the ODE and its correlation to the voltage.
Here is the solution:


texts: Altium Designer - Shielding footprint "component clearance" violation

texts:
I'm trying to make a footprint for an RF shield.
I made a footprint just putting few pads in square shape but the problem is that the Altium report me a "component clearance" violation.
How can I solve that?


texts: Calculation and measurement of input and output impedances of a Class-D amplifier

texts:
How would I calculate, from datasheet information or elsewhere, the input and output impedances of a Class D power amplifier, in general or for say a chip like the LM4670 or the TPA2000D1?

{Note that in TPA2000D1's datasheet, \$ Z_{in}\$ is given (about \$ 15k\Omega\$), but not \$ Z_{out}\$.}

What differences would there be to measuring the input and output impedances of a Class-D amplifier like this, from techniques used for other amplifier classes, like class A, AB, B, C?

Would the input and output impedances vary with frequency of the input signal?


texts: Removing output voltage ripple in high voltage outputs

texts:
I am looking to reduce the voltage ripple on a DC/DC converter operating at 5kV.

I have looked extensively on the internet and have found multiple ways to reduce output voltage ripple, an interesting reference is by EEVBlog which uses capacitance multipliers with BJT/MOSFET/Darlington transistors.

Multiple other sources state to use multi-stage LC filters, and high value capacitors, etc. However, when the output voltage enters the kV range, the use of inductors is avoided as much as possible, if possible. Furthermore the size of capacitors with large values rated for kV values are very bulky and again, would be avoided if possible. This brings limitations in the amount of voltage ripple that can be attenuated in this range - which makes designing low output voltage ripple DC/DC converters in ripple sensitive applications (such as travelling wave tubes) very difficult. Splitting a transformer secondary into multiple windings reduces the ratings of inductors/capacitors but to what extent does this beat having a single inductor?

Does anyone have any tips on how the voltage ripple can be minimzed in such cases?

I am planning on using HV rated silicon carbide devices in the isolated power supply so possibly something that utilizes a MOSFET in the rectifier can reduce the ripple.


texts:
I've got 5 little Sharp IR sensors I need to wire to an Arduino.

These are the sensors: https://www.sparkfun.com/products/242

Trouble is, I need to put the connections in a relatively small area.

Is there any reason I shouldn't "daisy chain" them together in parallel like this?

simulate this circuit – Schematic created using CircuitLab


texts:
My RC car uses 2 relays (9 V, SPDT) for it's forward/backward movement, as image below indicates:

However, RC car isn't able to be driven anymore. Specifically, servo works fine but motor can't spin. Instead, there is a sound came from the relay(s). I 'm thinking of replacing both relays to see if it works.

RC car powers up from a Ni-Cd battery (8AA) 700 mAh 9.6 V.

My question is:

Can a 9 V relay been replaced from a 12 V relay? In other words is it possible for a 12 V relay to be energised in this case?


texts:
so I've gotten a decent 1 layer toner transfer process down and I'm looking to add some nice touches to it before I move on to trying 2 layer boards.

Anybody know how to do a nice silkscreen layer or solder mask layer with toner transfer?

Thanks


texts: Relay - should low or high be used for 'On' best practice

texts:
This is possibly a pedantic question but im not sure what makes the most sense.

I have this relay : SRD-05VDC-SL-C  - the one seen here: http://www.circuitbasics.com/setting-up-a-5v-relay-on-the-arduino/

It has 2 modes.

Normally open, where the device is connected until a high signal is sent.I read this as the relay is normally open...i.e not interrupting the supply.

Normally closed, where the device is connected when a low signal is sent. I read this as the relay is normally closed, i.e delivering power until otherwise told to stop. (Although i think my explanations of NC and NO are wrong...is there a clear easy explanation of these terms!)

I want my relay powered device to be off by default...which can be done in either of these modes, by sending the appropriate signal. So the question is, which option do I use? Which is more right?

The relay module i actually have is actually : https://www.amazon.co.uk/gp/product/B06XKQQXKW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 . which is 8 relays, and 8 control leds.

The light for each relay is powered when the control pin is pulled low.

To that extent, it makes sense to me to use normally closed, so when the relay is brought low, my device turns on and the relay control led lights up.

My question surmised is: For the Relay status led , where light on suggests the relay is connecting power to the device should I be using NC here?

The other bit which I am unsure about is....when my ESP8266 is booting up, is there a chance that my relay control pin will go LOW before i want it to? The pin seems low by default? Is that true? If a pin is not LOW or HIGH, what is this 'unused' state called?

Is this 'best practice' when it comes to relays....this led is the bit which adds complication for me.

Please see here for a next step question : Relay active low and ESP8266 GPIO pins


texts: Electrical circuit analyses: coil and capacitor in series

texts:
I've a series circuit of a coil and a capacitor, in between those components we've a switch that will close when \$t=0\$. We can write:

$$
\begin{cases}
\text{U}_\text{C}\left(t\right)=-\text{U}_\text{L}\left(t\right)\\
\\
\text{I}_\text{C}\left(t\right)=\text{U}'_\text{C}\left(t\right)\cdot\text{C}\\
\\
\text{U}_\text{L}\left(t\right)=\text{I}'_\text{L}\left(t\right)\cdot\text{L}\\
\\
\text{I}\left(t\right)=\text{I}_\text{C}\left(t\right)=\text{I}_\text{L}\left(t\right)\\
\end{cases}\space\space\space\space\space\therefore\space\space\space\space\space\frac{1}{\text{C}}\cdot\text{I}\left(t\right)=-\text{L}\cdot\text{I}''\left(t\right)\tag1
$$

Using Laplace transform:

$$\begin{align}
\text{I}\left(\text{s}\right)&=\frac{\text{s}\cdot\text{I}\left(0\right)+\text{I}'\left(0\right)}{\frac{1}{\text{C}}+\text{L}\cdot\text{s}}\tag2\\
\text{U}_\text{C}\left(\text{s}\right)&=\frac{1}{\text{C}\cdot\text{s}}\cdot\left\{\frac{\text{s}\cdot\text{I}\left(0\right)+\text{I}'\left(0\right)}{\frac{1}{\text{C}}+\text{L}\cdot\text{s}}+\text{C}\cdot\text{U}_\text{C}\left(0\right)\right\}\tag3\\
\text{U}_\text{L}\left(\text{s}\right)&=\text{s}\cdot\text{L}\cdot\frac{\text{s}\cdot\text{I}\left(0\right)+\text{I}'\left(0\right)}{\frac{1}{\text{C}}+\text{L}\cdot\text{s}}-\text{L}\cdot\text{I}\left(0\right)\tag4
\end{align}$$

Well, I know that:

$$\text{U}_\text{C}\left(0\right)=200\tag5$$
$$\pi\sqrt{\text{C}\cdot\text{L}}<10\cdot10^{-6}=10^{-5}\space\Longleftrightarrow\space\text{C}\cdot\text{L}<\frac{10^{-10}}{\pi^2}\tag6$$

How can I find the value of \$\text{C}\$ and \$\text{L}\$ using the things I know?


texts: Considering lithium-ion variant when picking a BMS board

texts:
I have 4 Panasonic NCR18650B batteries and want to purchase a BMS to charge them in series. The following board looks promising, but I'm not sure if it's fully compatible with my batteries.

The main concern is that my batteries' chemical composition isn't specifically supported by the board I'm looking at. The board's product description says that it supports the LiCoO2, LiMn2O4, and Li(NiCoMn)O2 variants of lithium-ion batteries. However, my batteries are apparently of the LiNiCoAlO2 type (search for "panasonic ncr18650b" once on  the page).

Will my batteries be charged without issue if I use this BMS? There doesn't seem to be much emphasis on my battery model's chemical composition, as even the product datasheet doesn't mention it. Furthermore, this is the only BMS product description that mentions specific variants of lithium-ion batteries, whereas almost every other description just says that lithium-ion batteries in general are supported. According to the second link, my batteries' lithium-ion variant is similar to Li(NiCoMn)O2, which is supported by the BMS.


texts: Inaccurate output voltage from the Analog Multiplexer

texts:
I am using the analog multiplexer "MAX337" in my design to get the voltage drop over a shunt resistor from 8 branches, then i use a "INA118" instrumental amplifier with 500 gain to get the value by an ESP8266, everything is working great but the analog multiplexer is adding little bit more voltage to the input voltage drop, for example if the voltage drop of the first branch shunt resistor is 2.236mV the output of the multiplexer is 2.399mV which is changing the over all result and it is the same with all the 8 inputs of the multiplexer....can you please tell me where is the mistake i am doing, and of course if you see anything done in a wrong way or can be don't i a better way in my design please let me know.
Thanks in advance.


texts: Oscillating a circuit on and off repeatedly to save water

texts:
I am using a foamer unit (a device that intermittently drops a blob of foam behind a moving vehicle to mark its path). The problem is that it's dropping about 10 x more foam than I really need, hence using lots of unnecessary water.
I thus want to increase the time between each intermittent foam drop. I know nothing about electronics so want to use this as a first project! At the moment the foam has an on-off switch. I am thinking that the simplest way to reduce the foam used would be to add something that breaks the connection, for say 10 seconds every 5 seconds (when the switch is ON). So that when you flick the switch ON the foam unit will power on for 5 seconds then off for 10 then on for 5 etc etc etc. I would greatly appreciate any advice on how to do this (or other solutions to save water!).
I know I could do this with an Arduino & a relay but I don't want to have to use batteries to power the Arduino. (unless there's another way to power it?)
Sorry if this is a basic question! I have no electronics background but saving the wasted water would really be good.
Thank you!


texts: how to use Aux Output Signal to light an LED

texts: I have an Aux signal that I need to power a flashing light. I know the Aux signal itself does not have the power supply to do this. That's fine Because I can get power from somewhere else. My question is, Is there a device that will output an AC or DC voltage if sound is coming through? I can build one myself but I'm not familiar with enough of the electronics at work to do that without guidance. is there an amplifier or something else that would accomplish this?


texts: Why is there a maximum charging current much lower than maximum discharging current on a li-ion pack?

texts: I will have soon an electric scooter with a 60v (top 67.2v) and 35ah battery pack. As it is designed, it can be charged by one charger which pumps 2,5 amps or it can be charged by 2 chargers in parallel, pumping 5A. That's ok for city use, it can charge over night, there is no problem waiting few hours for a full charge. But from time to time I plan to take trips into forest, between villages, etc. and I may need to charge it on my way, much faster, in an hour or so. For that I can purchase a 60V and adjustable 5-25A charger to take with me and plug it where I can find a wall plug, then continue my trip. But searching on aliexpress for similar sized battery packs, I discovered something strange in the specifications. For a 60v 20ah pack, the maximum continuous discharge current can be as high as 50 amps, but the charge current is max 5A. Why?? The connections between cells clearly can support high currents, otherwise it cannot discharge with 50A without damage. Why is the charging max so low and what happens if I push 25A with a powerful charger? Thank you.


texts: How to capture USB data on the oscilloscope?

texts:
Using 2 channel oscilloscope (BK precision 2542B), channel 1 trigger on the triggered signal, channel 2 is on the Data+ of the USB port.

After sending the triggered signal to the bar code scanner, I can be able to read the data back and display it on the laptop terminal. However, I can't capture its data on channel 2 of the scope. I can only see the trigger signal on channel 1.

The scope GND leads were connected to GND on the board. What did I do wrong?  I just wanted to measure the timing how fast I get the data after sending the trigger signal.


texts: Import Parametric Sweep data from LTSPice into Matlab

texts:
In LTSpice, I am running transient simulations with input 2 parameters (Amplitude and Frequency) being swept. The initial graph of all the data looks like this:

Obviously it is hard to tell what is going on. I would like to import the large simulation data into Matlab for analysis, where I can separate the data into individual waveforms - each corresponding to an amplitude and frequency that was swept.

I found a file online that implements the LTspice2Matlab command that imports a RAW file, however it cannot isolate each waveform as I expected. Are RAW files stored in a manner that each data point is paired with its amplitude and frequency? If so, how can I properly import this into Matlab?

Any ideas are welcome!


texts: How RF Choke doubles Vcc at collector in BJT Power Amplifier

texts:
I'm trying to analyze a class A RF power amplifier as represented in the picture.  The main thing I'm trying to understand is how the collector voltage can go to 2x Vcc as according to this page.   The ABC’s of PA’s.   According to the author because VL=L(di/dt) Vce can swing from 0 to 2xVcc.
Of course I understand that the voltage across the inductor is V_L = L(di/dt), but what i don't understand is what constrains V_L = L(di/dt) to be between 0V and |Vcc|?  I would expect that V_L = L(di/dt) could take any arbitrary value depending on the collector current swing, Ic.
I though I might be able to understand by using something like state space analysis or systems of simultaneous linear DEs using the model below.
The equations I'm coming up with don't seem that helpful though.

For one thing I'm not sure how to define Ic in a way that would be useful.

If anyone could give me any suggestions I would really appreciate it. If there's a quick explanation of V_L and why  0V < L(di/dt) < |Vcc| it would be great.   I'd also like to be able to go back and analyze this to understand it better though.
Thanks a lot.


texts: Confusion with tracing current flow, and finding voltage of 2mA current source

texts:
Where there is a question mark, does the current flow there?

Also, why does current travels through the 6Kohm resistor, and it doesn't all go to the 2mA source?

Lastly, how would you go about with finding the voltage of the 2mA or 2Kohm source if no current goes to the 2Kohm resistor?


texts: Trying to Identify Static or Thermal Transfer Tape

texts:
I came accross this solidstate drive which is in a custom plasic and metal enclosure.
There is a sheet of material cut out between the metal top and the drive. I'm trying to figure out what it is, it's pinker than in the it looks in the picture below, and you can see it's a bit "crumbly", and has a mesh backing where the adhesive is.
Trying to establish if it's a type of antistatic tape, or thermal? or even just vibration dampening. but ive never seen anything quite like this material.
Thanks!


texts: If a module is "arduino compatible", does that necessarily mean it isn't compatible with other microcontrollers?

texts:
I'm trying to find a GSM module to pair with a PIC32 microcontroller for a project and I've found some nice ones. The one I'm really interested in is the SIM800C GSM module. Many of them say they are "arduino compatible." Does that mean they aren't compatible with other microcontrollers? As an example, take a look at this one.

It says it's compatible with arduino and raspberry pi which is great but I'm going to be using the PIC32. Do you think it will work?


texts:
I'm using Ethernet (CAT5/5e/6) cables to communicate with the PCA9615 Differential I2C buffer. These cables roughly have a characteristic impedance of 100 ohms, but I have a few questions about choices of terminating resistors.

simulate this circuit – Schematic created using CircuitLab

The datasheet for the IC gives an example of how to terminate one of the twisted pair ends. In there, they chose a combination of 600 ohms and 120 ohms for their resistors with the claim that the parallel combination yields a termination of 100 ohms at each end of the twisted pairs. Sparkfun also made a breakout board, but their choices were 390 and 100 ohms, so there's a slight difference.
 From what I've researched, the resistor between the two differential pins is the one that terminates the network while the other resistors act as pull-up resistors to VCC and/or ground. If we have the same terminating resistor on both sides of the cable, wouldn't the driving end see a parallel combination of the two (so in the image, the IC would see 60 ohms)? Wouldn't it be better to double it to match the impedance of the CAT5 cable?

Also, if some twisted pairs are not being used, it seems to be good practice to terminate them. However, if I'm using them for DC power and ground and not for signals, is it fine to not terminate them with a resistor?


texts: Would a magnet interfere with NFC devices in this scenario?

texts: I am thinking about manufacturing an interactive chessboard as a personal project. The circular pieces (resembling more or less poker chips in shape) would contain NFC tags, so it is possible for the devices hidden inside the board to collect information and update game state. Moreover, ideally, for convenience, I would want the pieces to also contain small magnets, so it is easier to move them. In this case, is it possible for the magnet and the NFC tag to not interfere with each other? If it is not, what alternative solutions can you see?


texts: I found this image somewhere on the internet and I am wondering what program is it.


texts: Method to find out if Microcontroller IC is counterfeit

texts:
To practice my SMD soldering skills and to try out stuff (self taught hobbyist level) I purchased various ATMega uC chips from Aliexpress. I know you never know what you get that way (usually what you pay for!), but I was wondering if there was a method to check if they are fake or not, now that I have them.
That's why I've been watching the video from Noel's Retro Lab, after what I purchased 2 of each chips from Farnell to compare the resistance between Vcc and Gnd pins with the Chinese ones.
Here are my findings, in Mohm:
            Farnell #1  Farnell #2  Ali #1  Ali #2
ATMega328PB 9.37        12.2        10.5    12
ATMega328PU 11.3        13.2        21      1.79
ATMega88PA  11          15          2.8     2.8

The ATMega328PB measures are consistant between Farnells and Alis chips, but the other two models seem "in the cabbage" (as we say in French) with random values (still, it's in the range of Mohms). Are those necessarily fake?
Another interesting finding is that all the models from Farnell share a similar resistance, between 9 and 15Mohm. I'm curious to know if it consistant among all ATMega chips, or is it a coincidence?
Anyway, does my measuring make any sense? What would be the next step to test those chips?
Thanks!


texts: A homemade programable voltage calibrator

texts:
I made a DC measurement board based on ADC and ARM. Now I want to add 'self-calibration in filed' function to it. I think I need a voltage reference and a voltage divider. And I don't want to calibrate my calibrator. I just need the voltage output error from the setting value (calculated from reference voltage and divide ratio) don't exceed 0.1% (because the voltage reference I used only has a initial accuracy 0.05%, so I don't expect the whole system can achieve the same accuracy with it). Now I have two ideas:

Use a resistor voltage divider network. If can't buy one, I need make it myself, using 0.1% metal film resistors. And I may need an analogue switch such as ADG seris, and precision OPs, etc.
Use a MDAC. The DAC may expensive, but it may need less parts than the method 1.

Any suggesions? Which one is better?


texts: Voltage ratings of capacitors: ceramic vs electrolytic

texts:
Now I know when it comes to electrolytic capacitors it's usually good practice to use a voltage rating 1.5x - 2.5x the maximum rating you ever expect the capacitor to be exposed to, as the lifetime can be significantly reduced by running it near its limits.

But does the same protocol apply to ceramic capacitors? For example, assume a 25V ceramic capacitor - will running it at 24V reduce its lifespan significantly?

I'm currently designing a PSU which needs to be reliable, so at the moment I'm using 50V caps for a maximum 20V input (35V caps aren't available), but I'd like to switch to 25V caps if possible.


texts: What is between oscillator and antenna for a simple carrier transmitter

texts: I have a 20.000 Mhz Crystal Oscillator Module. If I just wanted to transmit a carrier wave at 20 megahertz, what would be from A to B?


texts: How do I find the vector potential in this question (4)?

texts:
How do I find the vector potential in this question? What exactly is the 'region' being referred to?
I am using equation 334 in this. I am not able to get the bounds to integrate the formula with. Is z infinite? What would the radius vector be?


texts: L298N heating up when driving a Nema 17 with Arduino

texts:
I've just bought a Nema 17 (Motor NEMA 17 40mm 1,2A 2,6kg/cm 1,8º 42STH40 1204A CNC) to build a pet feeder, and to control it I'm using a L298N driver I've also bought. I've wired everything together as shown in the following photo. I attach a 12V, 1.5A power adapter to the female jack over to the right. The Arduino gets powered up from the 5V + GND from the L298N

I'm using Arduino's Stepper library and it works ok. However the L298N board quickly heats up and gets very hot, I cannot even touch the heat sink. I'm pretty sure I'm doing something wrong. Why does it get so hot?

Edit 1: Here are the specs of the motor.

4-wire bipolar operation
Compatible with NEMA17 standard
Dimensions: 42 x 42 x 40mm
Motor shaft diameter: 5mm
Step angle: 1.8 degrees
Step Count per revolution: 200
Standard Voltage: 2V
Phase current: 1.2A
Phase resistance: 1.7 ohm
Holding torque: 4N.m (minimum)
Weight: 290g


texts:
I'm looking for a push button switch that when you press it, it is open and then when you press it again, it is closed.  I believe this is called an "alternate action" push button switch.  Is this different than a "latching" push button switch?

Also, are there alternate action push button switches that have a "hold" feature?  That is, you press the button for X seconds and it closes, then you press it again for X seconds and it opens.  What is the terminology for that type of switch?  I've searched numerous websites but haven't been able to locate one, so I'm wondering if I'm using the wrong terminology.


texts: Controlling AC relay with a single push button?

texts:
Is it possible to set an AC relay (220vac coil) ON / OFF by using a single push button (non latching) and some extra components but without the need of an additional DC supply?
It doesn't have to remember the state when power is off.
This schematic is the only I found for an AC circuit but uses two separate ON/OFF buttons, and also I don't need the second relay or the shared off button.


texts:
I'm working on making a sign that will be outdoors in full sunlight and I want it to have the longest range visibility.

This is a project for university and I will probably need 100 LEDs or so -
I need the cheapest possible but I really want people to be able to see it from afar!


texts: Why do LEDs stay lit when a circuit is broken?

texts:
I've noticed occasionally that some LEDs stay on, even when the circuit they are connected to is broken. For instance: the "power" indicator on my computer stays on for a few seconds after I unplug it, and I have a another plug with a built-in LED that stays on at least 10 seconds after it is removed.

Why is this? I thought that if a circuit was not complete, current could not flow through it, and so an LED wouldn't work? And why is this specific to LEDs - I've never seen any other kind of light or motor stay on without power.


texts: I have a question regarding multi-strand wires. I use wires starting from 0.34 Sq mm to 6 Sq mm in my electrical cabinets. While connecting these wires in terminals, is it recommended to twist the wires? Could you please explain the pros and cons of twisted wire connections and straight wire connections?


texts:
I've a ATmega368, currently working on top of a Arduino Uno, which its final purpose will be to process some sensor information and send it through XBee (configured as a router) to the coordinator.

So, basically I've a arduino, which its Tx pin is connected to the pin 3 on XBee (configured as a ROUTER AT). All information I'm writing through the Serial.println() method is received perfectly on the coordinator in API ZigBee Receive Packet frames (0x90).

Now, considering that the API 0x90 packet is capable to hold 6 bytes of data, I was expecting that if I limited the output on the Arduino also to 6 bytes I would get only 1 frame with the full 6 bytes. But what it happens is that normally I get the full message sent from the arduino, broken into the several frames.

I think is mostly due to the packetization timeliness (set by RO) of data while waiting on the buffer. But considering I'm only sending data every 5 seconds or so, the packetization period always timeouts.

An option could be to configure the XBee as a ROUTER API, and build up the frame myself.

Any thoughts?


texts: Trying to make an inventory management system using barcode scanning upon transactions

texts:
I have a project in hand that is to enable long term management of boxes of goods in the store room. My idea was to use two barcode scanners to record the INs and OUTs of the boxes respectively. The computing unit (a microcontroller PCB maybe?) is to be able to:
 1. read and memorize each and every different rows of barcodes as different types of boxes,
 2. do simple plus/minus everytime it reads a scan from either the "IN-scanner" or "OUT-scanner"
 3. simple display it to the LCD

My main question is what does the microcontroller actually reads if i am to connect the barcode scanner to the PCB via a RS232 port, assuming that the barcode scanner itself has built-in ADC already?

My next question is what else has to be done on the data/signal before I can assign them with the initial number of boxes in the store room?

Hopefully any of u guys understand and could help me!
Thanks anyway!!!

Update:

Now that I have an USB barcode scanner, that types out the barcode numbers followed by an "enter", this leads me wondering will there be extra works to eliminate that "enter" keystroke command the microcontroller might read? Or after all, am i definitely needed a kind of decoder of the received data to make it readable to the microcontroller? what will that be? helps.. :)


texts:
I am working on a circuit for my deer feeder.

I now have a 6 volt power source running the spinner on the feeder and it has a 6 volts solar panel recharging the battery.

I made a new circuit control out of a disposal camera circuit trying to make a shocker device, of two cages, one interior and one exterior isolated separately and the shocker circuit connected to them, I get 300 volts to my cages.  This circuit requires a AA 1.2 volt battery.

How can I make the AA rechargeable battery, charge off the existing solar charger?

I have an idea but not sure.  Can I go off my solar charger that's existing and cut the voltage using a resistor circuit with a diode or make another circuit of several diodes in series and get down to the 1.2 volts?

Or option 2 second-ally build a 1 volt
 1 amp solar panel supply, adding a diode and connect that to the 1.2 volt battery that I want to keep charged for my shocking device.


texts: How does a decoupling capacitor handle a spike (increase) in the voltage from the power supply?

texts: From what I understand, when there is a drop in the voltage the current is drawn out of the capacitor and so the balance is maintained. But when there is an over voltage from the power supply or when the load draws more current how does the decoupling capacitor balance it. The capacitor is already fully charged. So when the load draws more current, doesn't that current get drawn from the capacitor/power supply?


texts: Can I half the current rating when moving from 100-240V to just 230V?

texts:
I am repairing a failed ATX computer power supply (PSU). It is rated 100-240V 9A input, 620W max output. Its 10 A bridge rectifier is dead, and I am able to get at most 8 A bridge rectifier as a replacement. 8 A is not 10 A, of course, but I live in Europe, we have got 230 V in mains, so my idea is simple: If the PSU is designed to work in a wide range of voltages from 100 V to 240 V without a manual switch, its 10 A circuitry is probably needed only for 100 V, but not for 230 V we use here in Europe. So I think I can safely put there 8 A rectifier bridge, or even go as low to 5 A or possibly even to 4 A without any problems. Is my idea correct?

I also replaced the blown 10 A glass fuse by a 4 A ceramic one, it should be just enough for the PSU and also can help to protect my 8 A replacement bridge from possible overcurrent.

My math: Originally 100 V, 10 A => 1000 VA. Now 230V, 4A fuse => 920 VA.

I tried it in praxis, it seems to be fine and working (under normal conditions, not fully loaded). So this is rather a theoretic question, I'd like to understand it.

Update:

If somebody is interested, it is Seasonic SS-620GB (S212II Bronze) ATX PSU.

Also, there is a fuse information on its printed board saying that 200-230V variants should be fitted with a 5A "H"-rated fast blow (T) fuse. I used the correct H T type.

Original bridge was GBU 1006: reverse current 5 microA, forward surge current 220 A.

The replacement is KBU 805: reverse current 10 microA, forward surge current 300 A.


texts:
Let's suppose I want to know the diode bias, how would KVL look when applied on this circuit assuming the diode is off? (Suppose Vin = 10V)

What I would do is: If diode is OFF current should be flowing (or try to flow) from right to left on the diode, so the right side of the diode need to have a higher potential than the left. Applying KVL from the battery counter-clockwise would lead to -Vin-Vd = 0, Vd=-Vin, Vd=-10V and the diode is indeed OFF. But I know that's not the correct answer... What is the mistake I'm making?


texts:
My AC adapter reads...
          Output: +12V DC symbol 12.5A
          Input:  100-240V~
                  50-60Hz 2.5A

I would like some clarification on if i'm reading/understanding this correctly. The input is the range in which the brick will work when I plug it into the wall and the output is what the brick pushes out for the computer (what the computer need to draw to power on when I turn it on). If say I were to have 20 of these same computers plugged in would I trip a standard 120V / 20A breaker in my home?

I know you add the Amps and make sure the total doesn't go over the 20A but am I using the 2.5A that the brick pulls or the 12.5A. Kind of a stupid question but its something that's always confused me when I look at it.


texts: How to shift signal phase in matlab from this circuit?

texts: The circuit shown is in matlab. Sinus signal is provided by vpin by connecting from PCI. The sinus signal is looks like on the scope. The problem is i want to shift signal phase, from the picture below is circuit needed to shift the sinus signal phase, but there's a red dot that i can't connect the shift circuit (R-C) with my sinus to shift signal phase... How to solve this? Is there any way to shift the signal phase?


texts: How do I set up serial communication between two Holybro Telemetry Radios?

texts:
I have two USB Holybro 915 MHz Telemetry Radios. These are usually used with Mavlink for communication between drones and ground stations, but I would like to use them to send small amounts of data - say, an integer every few seconds - from one computer to another, without using Mission Planner or the Mavlink protocol. One radio is plugged in (USB) to my Windows 10 laptop, another is plugged in (USB) to another laptop running Ubuntu. I have written a very simple python script in an attempt to send one byte of data from the Ubuntu laptop to the Windows laptop via the radios.

Sending (Ubuntu):

import serial
ser = serial.Serial('/dev/ttyUSB0')
ser.write(b'\x00')

Receiving (Windows 10):

import serial
ser = serial.Serial('COM8')
while True:
   print(ser.read(1))

It is my understanding that, at their core, these radios are simply USB<->Serial adapters which communicate over radio, so I should be able to send serial data from one to another. However, this is not the case. I will send a byte, say b'\x00', and it will receive something like b'\xfe' on the other end instead of b'\x00'. I've tried using different byte values, but for the overwhelming majority of them (with the exception of b'\xff' and b'\xfe'), the values will be received differently. Is there an error in my setup?

Thanks

Link to the radios I am using:
http://www.holybro.com/product/transceiver-telemetry-radio-v3-915mhz/

Firmware Version(installed via Mission Planner):
RFD SiK 2.0 on HM-TRP


texts: why phase controlled rectifiers are not used in the place of normal rectifier

texts:
I have planned to design a SMPS like the one in PC.In most smps,AC is rectified using bridge rectifier adn converted to high frequency AC and step down using high frequency transformer and bucked/boosted based on application.

Instead of going through these many process.why cant use a phase controlled rectifier and have required DC voltage.


texts: Does this interrupt improve performance even with while loop in ISR?

texts:
Note:  I am a beginner :) MCU: Atmega328p
Which program below burdens the CPU the least? Would it be a significant difference?
Objective: to make a more "efficient" serial monitor by reducing the CPU burden.
Both programs send the int num = 65534 to my PC where I can see value coming in repeatedly through a serial monitor. Program 1 uses a empty data register interrupt and program 2 does not use any interrupts.
Considering I am still using while (( UCSR0A & (1<<UDRE0)) == 0){} in uarttrasnmitinteger function within the ISR in program 1, does program 1 reduce the "workload" of the CPU compared to not using this interrupt such as in program 2 (see below)?
Program 1:
char snum[20];
int num = 65534;

int main (void) {
  uarttransmitenable();
  sei();
  while (1) {
    //no code here
  }
}

ISR(USART_UDRE_vect) {
  uarttrasnmitinteger(num, snum);
}

void uarttransmitenable(void) {
  UBRR0H = (BRC >> 8);
  UBRR0L = BRC;

  UCSR0B = (1<<TXEN0)| (1<<RXEN0) | (1<<UDRIE0);
  UCSR0C = (1<<UCSZ01) | (1<<UCSZ00);
}

void uarttrasnmitinteger(unsigned int num, char* snum) {
  utoa(num, snum, 10);
  unsigned int i;
  for (i=0; i<strlen(snum); i++) {
    while ((UCSR0A & (1 << UDRE0)) == 0) {}
    UDR0 = (char)snum[i];
  }
}

Program 2:
char snum[20];
int num = 65534;

int main (void) {
  uarttransmitenable();
  while (1) {
    uarttrasnmitinteger(num, snum); // same function used in program 1
  }
}

void uarttransmitenable(void) {
  UBRR0H = (BRC >> 8);
  UBRR0L = BRC;

  UCSR0B = (1 << TXEN0)| (1 << RXEN0);
  UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
}


texts: Frequency response of common source amplifier and Millers theorem

texts:
I was asked to draw the frequency response of a CS amplifier. The MOSFET has gate-drain capacitance between the input and output. This means that at high frequency, the output is shorted to input(the impedance of a capacitor decreases at high frequency). Which in turn says that there is a ZERO in the transfer function of the circuit.

But when I try it by using Millers theorem, the common capacitance between the input and output are resolved (see the pic). So there is no ZERO in the transfer function now.

So what does it mean? Whether the circuit has a zero or not?

Thanks


texts: How to calculate DC power consumption of a device

texts:
I've got an old car radio that I've mounted in my backyard, with some speakers. Right now it's running off an old battery I have, with a solar panel that trickle charges it during the day. I want to know, how many watts/volts it's using and what the solar panel is producing. The goal, would be to add another panel, so it can supplement the power more.. because I'm thinking about expanding it.

I've got a basic volt meter. If I have to buy something I will. I'm more cirious to learn about it then the


texts: Interrupt handling for a UART on PIC32 with C32 v2.00 compiler

texts:
I am very new to PIC32 chips (or any PIC chips) and I am trying to create an interrupts handler for the UART to be called when the UART receive a byte. I am using the PIC32MX695F512L PIC32 processor with C32 2.00 compiler on a development board.

I found this example code in another project online. The comments led me to belive that this interrupt would be called whenever the UART receives a byte. I added a break point to this function and a static counter to count how many times this function has been run.

In other parts of the source code I can send BYTES out of the UART and are being revived by my PC. I have tried sending BYTES to the UART from my PC but this function is never triggered and the function counter (UART1Info_count) never increases.

Source code

static BYTE UART1Info_LastByteRXed ;
static UINT32 UART1Info_count ; // Init elsewhere

BOOL Uart_Connect ( ) {

    UART1Info_count = 0 ;
    UART1Init();

    UARTConfigure       (UART1, UART_ENABLE_PINS_TX_RX_ONLY);
    UARTSetFifoMode     (UART1, UART_INTERRUPT_ON_RX_NOT_EMPTY);
    UARTSetLineControl  (UART1, UART_DATA_SIZE_8_BITS | UART_PARITY_NONE | UART_STOP_BITS_1 );
    UARTSetDataRate     (UART1, GetPeripheralClock(), 9600) ;
    UARTEnable          (UART1, UART_ENABLE_FLAGS(UART_PERIPHERAL | UART_RX | UART_TX));

    INTEnable           (INT_SOURCE_UART_RX(UART1), INT_ENABLED);
    INTEnable           (INT_SOURCE_UART_TX(UART1), INT_ENABLED);

    // Set Interrupt priorities
    INTSetVectorPriority    (INT_VECTOR_UART(UART1), INT_PRIORITY_LEVEL_2);
    INTSetVectorSubPriority (INT_VECTOR_UART(UART1), INT_SUB_PRIORITY_LEVEL_0);

    // configure for multi-vectored mode
    INTConfigureSystem      (INT_SYSTEM_CONFIG_MULT_VECTOR);
    INTEnableInterrupts     ();

    Rs485RxLineConfig();
    Rs485TxLineConfig();
    Rs485TxDisable();
    Rs485RxEnable();

    return TRUE ;
}

#define __UART_1_ISR    __ISR(_UART_1_VECTOR, ipl4)
void __UART_1_ISR  UART_1_InterruptRoutine(void)
{
    UART1Info_count++ ;
    IFS0CLR = _IFS0_U1RXIF_MASK;
    UART1Info_LastByteRXed = UART1ReceivedValue();
    UART1TransmitTestASCIICharacters( (UART1Info_LastByteRXed+1), 1); //reflect back character, incremented by 1
}

Other information

Processor: PIC32MX695F512L
Compiler: C32 v2.00
IDE: MPLAB X IDE

My question

How to I create a interrupt handler on receive BYTE via UART on PIC32 with C32 v2.00 compiler?

Note:
Updated source code example with UART init()


texts: How to use 74LS245 to level up signals form 3.3V to 5V?

texts: I am using FPGA 3.3 V outputs to drive 16x4 character LCD (5 V). I went through the data sheet 74LS245 and found this can be operated at Vcc 5 V and accept input voltages from 2 V. I am confused because data sheet has not mentioned the output voltage up to 5 V, will this IC suitable for my application?


texts:
i need to identify this transformer to find its datasheet. Found inside a no-turning-on SONY AIR-SA10, and when measuring the two secondary coils, with 110Vac applied on the primary, is 0Vca in both. Its strange because the secondary coils are not open circuit, although they meausure 2ohms and 0,7ohms, i'm not shure if i can consider this as short circuit on the windings or a normal really low output impedance.

Anyways, normal or not, i need to find a replacement, and i dont know the secondary coil requirements of the circuit.

I emailed SONY for the schematic and got no response.

Thanks for any help.


texts: Why are all the MOSFETs' drains connected together and to nowhere else?

texts:
I was studying the schematic for the "Waveshare UPS HAT", just because I am a beginner and find it educational. This part is really confusing for me:

Why are all the drains of those AO4406A MOSFETs connected together and to nowhere else? What happens there?


texts:
I want to build my own autotransformer.
In an autotransformer

Does current flow from source to load because it's demanding it via direct conduction just like in DC? Or Is it due to back-emf that produces the current in the winding by the main flux needing to establish stability of the flux hence producing the current? If it's the former. So the purpose of the magnetic flux in autotransformer is only to cause inductance creating some kind of resistance so the winding won't be seen as short, and current feedback still work like in DC? If not, why not? Can't current demand pass through the inductance producing direct conduction like in DC?


texts: Cooling a 2,000V laminated steel transformer?

texts:
I have a 2,000V laminated transformer, I use it for high power applications, it gets hot quickly. I was thinking of cooling it with distilled water or mineral oil, but can't think of any decent way to cool the coolant, can someone point me in the right direction.

I guess thanking the community for there answer is something abnormal around here...


texts: Arduino to read file data from SD storage board, and PC user to update same file via usb cable as needed

texts:
I have a project where in the finished product (sketch loaded to Arduino and it's running on its own), Arduino needs to regularly read data from a text file stored on a SPI Micro SD storage board (the ones sold on ebay). The problem is that the same file also needs to be regularly updated by a user by using a PC connected to the system via a USB cable. The user to simply use Windows Explorer to browse and open the same text file stored on the SD card and edit/save it with notepad.
What is the simplest way to accomplish this? What hardware do I need? Is there a SPI Micro SD storage board that also has a slave USB connector (and its interface hardware) to allow access to the file system on the Mirco SD card with PC's Windows Explorer?


texts:
i'm having af hard time finding the proper MOSFET for my wireless power transfer. I need a MOSFET which can easily do 100kHz without overheating and with minimal power dissipation. I'm currently using IRLZ44N but it's not optimal.

Resistor R6 is changeable, but i'm keeping it on 10 ohm, which draws approx. 400 mA.


texts: Modifying a soldering iron for lower power

texts:
I have a 60W soldering iron, which is too much heat for typical electronic soldering purposes. I find myself constantly switching it on and off using a powerstrip to control its temperature so it does not get too hot. I was wondering if there exists some easy way to reduce its power output. Is there some type of circuit I can build which could limit its current draw to only 100mA (so it would be a 12W iron) for example?

Maybe I could wire a 40W lightbulb in series?


texts: 24V output with microcontroller using mosfets

texts:
I want to controll 24V output which will be used by PLC with 3V3 logic uC.

I've created sth like this:

Q1 is my output from uC. VIN1 is supply voltage and COM1 common of it. I want to have various output voltage (like 5-24). But let's focus only on 24V now.   Will this circuit work? What if there will be no load on Q1OUT? Will transistor boil to death? Am I missing something?

Thanks in advance and best regards,
g.voooo16.


texts:
In my search on building a simple voltage controlled gate delay i stumped upon this chip.

After reading the datasheet i'm still very uncertain if this is the ic i need.

From what i understand: it is programmed using a simple voltage divider and this determines its POL and DIVCODE state.

I need a VC delay that alternates between a rather small ∽1μs and large ∽ 4 sec delay.

But after looking at page 11 and the Table at page 12 of the datasheet it looks like the DIVCODE states has a fixt (still variable) time delay (Recommended tDELAY).

Or am I wrong and could this chip actually vary from its voltage controlled input from 1μs to 33.6 seconds like the fist lines of the datasheet suggest?

Thank you for reading.

http://cds.linear.com/docs/en/datasheet/699412fb.pdf

Notes:

  Added from OP input with light editing.
  These were added as an answer - which may be a good choice**. We can leave them here or as an answer as desired.

I’m very inexperienced and have some difficulty dealing with the equations from the datasheet but understand almost all what has been described so far.

I can’t program AVR or PIC and or make complicated circuits. So this project is for me to learn a bit more.

The application is for a modular synth module, where the gate signals come in externally and the voltage controlled signals come in externally thus from other modules.
  So the gate signals ratio is all in rather musical tempo’s but the more experimental delay time the better. This to create swing/time offset between a steady flow of gate signals, where I could control the delay time using a simple VC signal from gate to gate in all different tempo’s.

I was first looking at Bucket-brigade devices and had already settled with a limited delay time.
The MN3207 does 2.56ms ∽ 51.2ms for instance which is nowhere close to 1μs and could create some timing problems. These require an external clock, which is a disadvantage compared to the LTC6994-2.

The maximum required rates of incoming gate signals is about 20ms per gate. So rise time’s are 40ms apart. This is really fast in musical terms.. (200bpm and 32th notes).
Minimum could be 200ms between rise times or so ( 38bpm and 32th notes).

In this module (idee) the voltage controlled delay time response could be set (fine tuned) using a maximum delay time variable resistor and a offset variable resistor that lifts 0v of the VC input. in my op-amp circuit, of the VC input.

The response time and settling time for a new delay time to be programmed (via vc) should be between rise times of the maximum requirements.
I don’t need a smooth variation if this means it effects incoming gate lengths, I would prefer the gate time to change in 0v state but since its all experimental it doesn't really matter.

I think I roughly get the inner workings now and how the division work, I’m thankful for that.
Although looking at page 17. it says: voltage VCTRL sources/sinks a current through RMOD to vary the ISET current.

What I interpret as that it is possible to vary delay time on the set pin using voltage controlled signals? Although in the range of the programmed division.

At this point if its possible to control SET using VC?, i’m thinking of settling with DIVCODE 4 (4.096ms to 65.54ms) and if its possible to ad a switch to change R2 to program  a larger delay time, I would like to know.


texts: How to obtain exactly the same state after deepsleep() mdbed function on a STM32L073RZ?

texts:
I try to configure my STM32 to obtain the lowest power consumption. For that I'm using deepsleep() function from mbed librairies. Before that I disable GPIO with this function

void SystemPower_Config(void)
{
  /* Enable Power Control clock */
  __HAL_RCC_PWR_CLK_ENABLE();

  /* Enable Ultra low power mode */
  HAL_PWREx_EnableUltraLowPower();
  //pc.printf("1\r\n");

  /* Enable the fast wake up from Ultra low power mode */
  HAL_PWREx_EnableFastWakeUp();

  GPIO_InitTypeDef GPIO_InitStructure = {0};
  GPIO_InitStructure.Pin = GPIO_PIN_All;
  GPIO_InitStructure.Mode = GPIO_MODE_ANALOG;
  GPIO_InitStructure.Pull = GPIO_NOPULL;

  HAL_GPIO_Init(GPIOA, &GPIO_InitStructure);
  HAL_GPIO_Init(GPIOB, &GPIO_InitStructure);
  HAL_GPIO_Init(GPIOC, &GPIO_InitStructure);
  HAL_GPIO_Init(GPIOD, &GPIO_InitStructure);
  HAL_GPIO_Init(GPIOH, &GPIO_InitStructure);
  HAL_GPIO_Init(GPIOE, &GPIO_InitStructure);
}

My main look like that

int main()
{
    Board_Init();
    while(1)
    {
        SystemPower_Config();
        wait(0.1);
        deepsleep();
    }
}

To generate interuption I use RTC alarms to leave the deepSleep mode. This part work fine but the problem is, the first time(during the first deepSleep) my consumption is equals to 1uA. After that my consumption is around 2.5uA on each deepSleep. So I think the deepSleep function change something the first time in the registrers or something like that. Have you any idea ?

Thank you very much for your help angain.

Simon NOWAK


texts: Replacing a relay with transistors in this step down circuit

texts:
I've made a simple circuit to step down voltage from 12V+ to around 5V, and while it works, it is noisy and it requires much capacitance. I would prefer to make it using transistors instead of relays. I would like to replicate whenever I want, with salvaged pieces, so I want to avoid voltage regulators ic's.

Circuit running:

http://postimg.org/image/m97k4ugg7/

I've tried to do it myself but I failed with transistors (mosfets). I think it requires to have a part that would act like a current sensor but I don't have the knowledge to make it.

simulate this circuit – Schematic created using CircuitLab


texts: I'm working in an experiment with high voltages and unfortunately a high voltage AC source is affecting the signal in my BNC coaxial cable (which is going into an oscilloscope or some other measuring device). Is there an easy or standard way to implement balancing as in audio XLR cables?


texts: I was wondering what does FIDU mean in the schematic below and what is it used for ?


texts: What Wattage does my resistor need to have to be save to dim an LED strobe module?

texts:
I want to dim a commercial LED strobe module and can't seem to figure out what wattage the resistor needs to be. Most posts are about single or multiple LEDs with their known forward Voltage etc. like e.g. this post here demonstrates.

My module however is a self contained unit with, as it seems, Voltage regulation and micro controller integrated.

The LED strobe module is an emergency vehicle strobe mini light bar type:

Voltage: 12-24 / 10-30 VDC,
3 x 3 watt LED elements,
Average current draw: 500mA@12.8 VDC,
Max current draw: 700mA@12.8 VDC,
Self-contained 22 flash patterns

I will run it on approx. 13.9V on a motorcycle (both battery and running engine) and found that a 400 to 500 Ohm resistor gives me the desired brightness.

I arrived at 400 to 500Ohm by trial and error using 3W rated resistors, which I believe are overkill for the final circuit.

My test rig is an 18V Li Rechargeable for a power drill, actually giving 19.2V and using the 500ohm the voltage drops to about 9.35V for the light module.

I tried to get the Wattage using this power source thinking it'll be save enough on the lower Voltage on the Moto:

W = 0.7A * (19V-9V) = 7W ?

It's huge for a LED light plus the 3W resistor barely gets warm. I suspected something in the range of about 1 to 2 W hence testing with  3W resistors.

Can somebody shove me into the right direction? What have I missed here?


texts:
I'm looking into modding an old battery charger, but I want to understand exactly how it works before I start. What is the purpose of the choke in this circuit?

Some people at my work have suggested the choke should be on the output of the bridge rectifier not the input - but it was obviously manufactured this way for a reason. Why would you want a choke on the AC side of a bridge rectifier?


texts: designing a state machine to detect a certain bit

texts:
So, I need to create a state machine (mealy machine) to detect the bit 1010 and also I need to code it in verilog. Here is a picture of my state machine:

So, I created the state machine and Now I need to code it in verilog:

module sm(clock,x,y);
input clk, x;
output y;
reg y;
reg[1:0]s = 0;
always @ (posedge clk)
        case(s)
        0: if(x) s <= 1;
        1: if(!x) s <= 2;
        2: if(x) s <= 3; else s <= 0;
        3: if(x) s <= 2; else s <= 1;
        endcase

    always @(*)
    case(s)
    3: if(x) y = 1; else y = 0;
    default: y = 0;
    endcase

endmodule

I barely learn this today. So, I was wondering if my verilog code is correct. any help/suggestion is appreciated. Thank You :)

simulation results:
[![enter image description here][2]][2]

new sim:


texts:
simulate this circuit – Schematic created using CircuitLab

I'm using an 8-bit shift register on a very basic application for learning purposes, I have three buttons connected to SER, RCLK & SRCLK pins, OE & SRCLR are LOW, reverse output is empty since I'm only working with one chip, and the 8 outputs are connected to LEDs.

The behavior is kind of unexplainable, I expected that pressing the clock button while the SER button is HIGH/LOW will define the input data, and then the latch button will display the output on the LEDs, but somehow the three buttons have the same behavior, they either turn all the LEDs on or nothing happens.

I know I should probably show what I'm working with, but wires are everywhere and I doubt that would be helpful.

Thank you


texts: Does anyone recognize the software in whitch these circuits were drawn?


texts: Is it possible to make a non-inverting difference amplifier?

texts:
For a crude current sense application I am wondering whether it is possible to build a non-inverting difference amplifier without common mode offset on the output.

Reason: I would like to avoid having to create a negative supply voltage just for this function.

I.e. I am looking for the following output:
Vout = gain * (V2 - V1)     where V2 > V1


texts: Difference between resistor in conventional flow vs resistor in electron flow?

texts:
I understand the differences between conventional and electron flow. What I don't get resistors in conventional flow. Take this schematic as an example:

simulate this circuit – Schematic created using CircuitLab

Using conventional flow, one would expect the current to flow through the resistor, into the LED, and back into the battery. What doesn't make sense to me is how the LED doesn't burn out. Yes, there is a resistor, but if we use electron flow - the current flows into the LED first; not the resistor. How does the LED not burn out?


texts: Is there a threshold voltage below which batteries are definetly dead and has to be recycled?

texts:
I have a particular case, where I purchased a brand new LiIon battery for an iPhone SE that showed 3.82 V in the beginning. I connected the battery to the circuit and after an hour or so, it showed 2.7 V. Then I disconnected the battery from the circuit, and kept it aside. Now after few days, the battery shows 0V. Does it mean the battery is faulty or it just needs to be recharged?

On a similiar note, does the NiMh and Alakline battery also have threshold voltages, below which they arent usable anymore and needs to be recycled?


texts: How to reduce the number of pins for three 7 led segment?

texts:
In my project I need to use

7x tact switches

6x LEDs

3x 7 led segments

1 arduino uno board

my prof says we can use any ICs
but arduino uno's pins cannot accomodate all those needed values.
I need to manipulate all the tact switches and the 6 LEDs so the only thing that can be reduced is the issue with 7 led segment.

Can you suggest a way that I can reduce the number of pins needed to be used in arduino uno?


texts: Why is conduit for 120V building power metallic?

texts: I saw wire conduit being installed in a building, and it was metallic.  Wouldn't you want to use an insulating material instead?  What if the live wire sheath started to fail?  It would short to the metal conduit.  Isn't that something worth avoiding?


texts: Design recommendation with LED Array Design

texts:
I am designing a LED array. I am planning to use 12 White LEDs of 0.5W each. It has 150mA forward current and Forward voltage of 3.6v.

I have a power supply of 12V,1A

Here is my Schematic for it.

Here is the Forward Current vs Forward Voltage Graph for the LED

Is supply enough for glowing the LEDs to its fullest? Is supply current and voltage is enough for the array design? Resistance value is enough to drop voltage ?


texts:
I am using a L6470H as step motor driver. The data sheet told me to use the following configuration for voltage pumping:

simulate this circuit – Schematic created using CircuitLab

(Value of C1 and C2 is not correct). I used a combined diode with 40V breakdown voltage, and 250 mA as forward current as D1 and D2 ((Datasheet)), after I assumed that the maximum voltage will be 2*12V. Nevertheless it burned on the first live test. What should be the maximum resistance of the diode? 48V? How can I calculate that?

Update: Apparently the problem was in the Driver, after VBOOT has a direct connection to GND, leading to 12V/20A max going through the diode array.


texts: Can you please help me solve this circuit?

texts:
So I'm trying to solve for \$V_n\$.
the way I solved it is by:
$$4I_x5+ 15I_x+ 5I_x= 15$$
$$I_x= \frac{15}{40}$$
then \$v_n= 7.5\$
What do i do wrong ?


texts:
I have a mouse wheel that's acting up and even after taking it apart and cleaning it inside out very well, there seems to be some dirt inside the rotary encoder of the mouse wheel. Blowing it with air didn't help.

I have cleaned potentiometers before using IPA with success and I noticed it has similar tabs so I'm guessing you open it up the same way as potentiometers.

I've heard there's optical and mechanical encoders but I'm not sure what mine is. My guess is that if it's optical it will have a transparent disk inside it but to that I have to unsolder it. I have put this on hold to plan it a bit first and make sure I have all the materials I need for the repair.

Is it ok to use IPA to clean a mechanical encoder or will it mess up any lubricant that's inside? And if it does (and assuming there's no better option) what kind of lubricant should be used after?

Same if it's optical: Will IPA ruin the print on the disk or is it safe to use?

Any further advice on repairing rotary encoders would be much appreciated as I recently started working in repairs and although the most common way to go about it is to replace the part, I'd like to be able to repair it (because of an interest in vintage synth repairs where parts are very often obsolete or hard to find).

As requested, a couple of pics of the encoder:


texts: components within a triangle in an electronics diagram

texts:
I'm trying to understand the following circuit diagram:

Specifically, the four triangles within the L293D component. So I understand there are two transistors in there, connected in series from 24v to ground, but what is connected to the bases of the transistors, the lines just end...

From what the circuit should do, I guess that the line coming in to the triangles from the 'and' gates (at the top left of the triangles) should some how enable the whole triangle, and that the line coming in from 1A\2A\3A\4A should toggle 5v between the two transistors. Is that right? And how do I deduce that from the schematic?


texts:
I have this really old NAND gate that I need to replace.

As you will see, the datasheet is worthless and it is the only one that I can find.  This is my first experience using a NAND gate (I starting classes for embedded micro controllers and electronics, after getting interested in arduino).

I know there is probably no way to tell me definitely, but I found 74ACT1100 on Mouser.  If I just get one of these (matched by mouser search for same number of pins) will it be suitable?

Is this pinout common among all that make these chips?  The datasheet is so blurred and in bad shape I can't tell what I'm looking at.  All of the TI chips seem to have this same pinout (only TI results returned from my Mouser search).


texts:
I need design a variable precision current source which able to produce 1nA to 10mA. The current output will be controlled through a Micro controller using a DAC. The purpose this circuit is to calibrate another device which need 1nA to 10mA.

I did some research and found below options:

Analog Devices: Precision Nanoamp Bidirectional Current Source
Not enough information  to how can be modified for my application
simple opamp and Mosfet which output current should be I = Vdac/(R4 or R3) Figure
Also I read about  Multi-Range Current Pump too.

simulate this circuit – Schematic created using CircuitLab

(*forget about the part numbers on drawing, just for reference)

Please let me know if any of these option will work for me, or if there is better option out there.

How can I design a precision 1nA - 10mA current source circuit?


texts: Why doesn't the compiler use directly LSR

texts:
Hi I've been working on a project using an Arduino Uno (so ATmega328p) where timing is quite important and so I wanted to see into which instructions the compiler was converting my code. And in there I have a uint8_t which I shift one bit to the right on each iteration using data >>= 1 and it seems the compiler translated this into 5 instructions (data is in r24):

mov     r18, r24
ldi     r19, 0x00
asr     r19
ror     r18
mov     r24, r18

But if I look into the instruction set documentation I see an instruction which does exactly this: lsr r24

Do I overlook something or why isn't the compiler using this as well? The registers r18 and r19 are not used anywhere else.

I'm using an Ardunio but if I'm correct it does just use the normal avr-gcc compiler. This is the code (trimmed) which generates the sequence:

ISR(PCINT0_vect) {
    uint8_t data = 0;
    for (uint8_t i = 8; i > 0; --i) {
//        asm volatile ("lsr %0": "+w" (data));
        data >>= 1;
        if (PINB & (1 << PB0))
            data |= 0x80;
    }
    host_data = data;
}

As far as I can see the Ardunino IDE is using the AVR gcc compiler provided by the system which is version 6.2.0-1.fc24. Both are installed via the package manger so should be up to date.


texts: Anyone can tell me what type of resistor and what is ohm and watt of this resistor?

texts: I have this burned resistor and dont know the value of this resistor.


texts: Thevenin equivalent (verification of answer)

texts:
\$ R_{TH} = R1 + R2//R5 + R3//R4\$

Then considering the current source and the resistance R3 as a Norton circuit, one can convert it to Thevenin as follows \$V_I = -IR3\$. Then we have the voltage sources in series so

\$ V_{TH} = V1 + V2 -IR3\$

Does this make sense? If not how do I fix it?


texts: How can be creepage between two conductor points be determined for HV pcb design?

texts:
I have read about spacing at HV design and it seems to say that there are two main standards to be followed: IPC or UL (IEC). IPC is a generic and commonly used. But UL is the best option for designs that will be used internationally.
But I have also read in other post that UL 840 could be applied.

There are some clearance and creepage calculators based on UL (60950-2n edition) or IPC which are useful when you have not access to these standards. This is my case at this moment. So I tried to use the calculators.

My board will have 6KV of working voltage: some points with 6KV, other one will be 0V or 12V when system will be ON.

But trying to use them something is wrong:

for creepage calculation. It only works until 1000V IEC/UL based calculator1. I can' t input 6000V there, it gives me an error.
for creepage and spacing calculation IEC/UL based calculator2. When I change parameters (pollution, material, etc) it gives the same creepage distance value for all the cases. I 'm not sure it could be a good thing.

When I use creepage calculator 1 for 1000V it gives me different values comparing with the calculator 2 using the same parameters. So online calculators  do not give me any confidence.

Here I have 2 questions:

On the one hand I would like to know which standard tables must I follow for creepage?
On the other one I'm asking for confidence calculators that can I use, especially for creepage.

Extra information about my case:

At this early point I don't really know pollution neither insulation degrees (functional, basic, etc..). Wire insulation and resistivity test, is our field. The market target could be any location of the world. This is the first time we will develop equipment with this voltage level. So, I thought to design keeping the worst case in mind. The kind of board I will design is wired relay based (its HV connectors has wires), coil relay controled by 12V signals. Not much more on the PCB. Well, it also has some wire-PCB connectors. Manufacturer offered to me CTI1 or CTI3 material. I'm considering to put HV connections/traces on the top and low voltage connectors and traces on the Bottom. I would like to add GND and VCC planes.

I keep in mind to use conformal coating after placing components. I'm waiting for the answer of the manufacturer for working with kapton instead of solder mask. After literature and researching I have learnt these 2 tips for isolation reinforcement.


texts: Android-Based Projector Remote Controller

texts:
I am planning to create an android application which is a remote control for projector. The android application should do the following:

Control the Focus Ring of the projector using Stepper Motor.
Change the angular elevation of the projector.
Position the projector up and down using a Linear Actuator.
Clone the original IR remote control of the projector.

I will be using Arduino Mega for this project and Blutooth Module for android device - Arduino Mega Communication.

I have found out that it is possible to clone the protocol of IR remote control using 3 pin IR Receiver. But most of the examples online are done on TV. Some used IR remote control to turn on LED's. I just want to ask if RC's of projectors are just similar in to TV's or any audio system. Is it possible to decode their protocol? Do I need to use some library which does not come with arduino sdk?
Since I will be using a stepper motor to rotate a focus ring, what would be the best way to detect if the focus ring can no longer be rotated or has reached its limit so that my stepper motor will not force the ring to rotate?


texts:
I have a small hw product and I would like to find a plastic enclosure company that do small runs.

Recommendations with experience please (i.e. not a simple Google Search result dump!)


texts:
I'm having trouble supplying 300mA to an led COB using an IRF520 MOSFET as PMW, controlled with arduino nano.

What is the maximum Frequency, in which I can turn the led on and off in this setting?

In the IRF520 DATA sheet:
Turn on delay time: 8.8ns

Rise time: 30ns

Turn off delay time: 19ns

Fall time: 20ns

Is the maximum Frequency then 1/(sum of above numbers) for the IRF520?

And for the arduino timers, are they all 16MHz or does it change from pin to pin?

What is the correct calculation (please give details if different pins result in different frequencies) to determine my maximun possible operating frequency (MOSFET + arduino)?

Thanks


texts: How do digital multimeters measure capacitance?

texts:
How do digital mulitimeters (DMM) measure capacitance through their typical 10M Ohm input/output impedance?

Providing a logic level of 3.3V, attempting to measure 1F would mean a time constant of 10M seconds (R x C) thus the voltage rise in the capacitor being in immeasurable (in the noise floor.) They also do it within a second or so at 3% accuracy. How on earth is this achieved?


texts: How to calculate currents and voltages with transistors circuit

texts:
I'm reading the Art of electronics and trying to calculate current and voltages of the following scheme:

simulate this circuit – Schematic created using CircuitLab

I wrote the current as the letters with indexes (I1-I9).

So I got the following equations:

I1 = I5 + I6
I2 = I3 + I4
I9 = I6 + I4
I8 = I7 + I5

Also we know that:

I1 = 5/1000 = 0.005A
I2 = 5/1000 = 0.005A

Then I tried calculating the first transistor's current (on the left side):

I7 = V/R = (5 - 0.6)/25K = 0.000176A

Then I used the general rule that:

Ie = b * Ib, where b=beta coefficient, Ie - emitter current, Ib - base current

So we got something like:

I8 = b * I7

Lets say b = 100, then

I8 = 0.000176 * 100 = 0.0176A

From I8 = I5 + I7 we get that:

0.0176 = 0.000176 + I5

giving us:

I5 = 0.017424A

I1 = I5 + I6:

0.005 = 0.017424 + I6

I6 = -0.012424A

And here I don't understand why its minus.
Whenever transistors and diodes comes into the circuits I can't estimate the voltages and the currents. I think that I'm missing something there.


texts:
I make music with an Arduino and old floppy drives and I also saw people making music with tesla coils. I've seen tesla coils for sale for about 200$ which seemed good, but there are some doubts:

Will it even pass the customs (in germany) ?
Is it legal to have one at home?
Can you use one without disturbing radio, TVs and telephones within the entire neighbourhood?


texts:
I'm working on a project using a Spartan-6. I created a FIFO with the IP Core Generator (New Source -> IP Core -> FIFO -> Generate). The LOG looks like this

The IP Catalog has been reloaded.
Qt: Untested Windows version 6.2 detected!
INFO:sim:172 - Generating IP...
Resolving generics for 'FIFONineBit'...
Applying external generics to 'FIFONineBit'...
Delivering associated files for 'FIFONineBit'...
Delivering EJava files for 'FIFONineBit'...
Generating implementation netlist for 'FIFONineBit'...
INFO:sim - Pre-processing HDL files for 'FIFONineBit'...
WARNING:sim - BlackBox generator run option '-ifmt' found multiple times.
Only the first occurence is considered.
Running synthesis for 'FIFONineBit'
Running ngcbuild...
Writing VHO instantiation template for 'FIFONineBit'...
Writing VHDL behavioral simulation model for 'FIFONineBit'...
WARNING:sim - Overwriting existing file
C:/Users/Christian/Dropbox/workspace/masterarbeit/VHDL/vhdl_work_in_progress/
DifferentialAttack/ipcore_dir/tmp/_cg/FIFONineBit/doc/fifo_generator_v9_3_vin
fo.html with file from view xilinx_documentation
Delivered 3 files into directory
C:/Users/Christian/Dropbox/workspace/masterarbeit/VHDL/vhdl_work_in_progress/Dif
ferentialAttack/ipcore_dir/tmp/_cg/FIFONineBit
Delivered 1 file into directory
C:/Users/Christian/Dropbox/workspace/masterarbeit/VHDL/vhdl_work_in_progress/Dif
ferentialAttack/ipcore_dir/tmp/_cg/FIFONineBit
Generating ASY schematic symbol...
INFO:sim:949 - Finished generation of ASY schematic symbol.
Generating SYM schematic symbol for 'FIFONineBit'...
Generating metadata file...
Generating ISE project file for 'FIFONineBit'...
ERROR:sim - TclTasksC:project_006: Exception detected while executing [project set].
ERROR:sim - Failed executing Tcl generator.
ERROR:sim - Failed to generate 'FIFONineBit'.  Failed executing Tcl generator.

Wrote CGP file for project 'FIFONineBit'.
Core Generator create command failed.

I already created the project new all over again but it didn't help. Can someone help here?

Update:

If I create a FIFO with the IP Core Generator in standalone mode (Thanks to Paebbels) it fails while Translating with an error:

ERROR:NgdBuild:604 - logical block 'GEN_FIFO[13].FIFONineBit_I' with type
'FIFONineBit' could not be resolved. A pin name misspelling can cause this, a
missing edif or ngc file, case mismatch between the block name and the edif
or ngc file name, or the misspelling of a type name. Symbol 'FIFONineBit' is
not supported in target 'spartan6'.

UPDATE2:

I did solve this on my own. I added the ipcore_dir directory within the translate process properties to the Macro Search path (-sd switch). That worked out! Thanks for your help!


texts: It's my first time using Altium Designer Software and I have encountered this "problem". With some pins I can route from the capacitor directly to the Gate Driver but with other ones I can't and the only way i found is routing from the pin to the component. Doing it this way this small green points appear. I would like to know what does it mean and why it happens. With the second pin from the left side in the bottom it also happens, but not with the first one.


texts: Trouble analyzing BJT circuits when we change β from very high to 100

texts:
For example we have this circuit:

Originally we assumed β to be very high and we assume VBE = 0.7. So for this, we have IB = 0 and therefore V1 = -0.7V and V2 = 3.4V.

Now that we have β at 100, IV1 is still 2*10-3 but now IV2 = αIV1 where α = 0.99 so we get IV2 = 1.98*10-3.

We also have now instead of IB = 0, IB = IV2/β = 1.98*10-5 and therefore VB = IB *47k = 0.9306

So then, V1 = VB - VBE = 0.2306V. I don't have any other of what the answers should be but I do know that V1 should be -1.63V and I'm not entirely sure where I've gone wrong.


texts: Options for replacing a broken charger when dealer no longer sells these

texts:
First post on this exchange, please do not delete it as a "request for shopping recommendation", this is close to, but not intended as one of those.

We have a Trimble DiNi 22 which runs fine, but we broke the battery charger. A repair is possible but impractical, so I am exploring my other options.

The original charger comes in three parts (mains cable; adapter; cable from adapter to battery), so we seem to have two general routes shown below. I've had no luck with my searches so far.

Find a generic replacement for the charger, keep the battery cable.

The specs for the charger are in this extract from the manual. Please also see this photo:
The Trimble part number is 571 906 330. Used original replacements cost £100+ on ebay, this seems to be my best bet for now but I would prefer to have other options.
The out port seems like S Video, but I don't have a real S Video cable to prove it, and it seems odd this port would be used on a battery charger.

Find a replacement charger which would plug straight into the battery.

I have not been able to identify the port on the battery, the distance between the outer pins is 8mm:

My questions are:

I know it's unlikely, but does anybody on here know a direct
replacement for this charger?
Can anyone identify the port on the charger end of the cable so that
I can try and find a replacement charger that will accept our cable?
Can anyone identify the port on the battery end of the cable so that
I can try and find a replacement charger charge our batteries?
Can anyone think of a suitable battery holder/adapter which would allow us to use a different battery in this instrument?

I hope the questions are clear, but please tell me if I can improve my question.


texts: What determines the direction and cause of electric field exerted on test charges?

texts: -I understand when there is an on-going electric field, if it is produced by a positive charge, the direction of electric field is away from it etc. And, if we get a +ve test charge, it repels it, and the force is also the same direction as the field. However, I can't understand why and how we know the main electric field is + or - charged? What causes it? And, if electric field is produced by electric charge, how come the test charges don't change or affect the main field? (Sorry, if I make no sense!) For instance, what causes and determines the direction of electric field in a DC power line?


texts: How to size The DOL Motor Starter knowing that the motor is a part winding start motor

texts:
I have a BITZER compressor type 4GE-23Y-40P, with a part winding start option of the motor

Nennspannung = nominal voltage = 380-420
Frequ = frequency = 50
Betr. strom = maximal operating current = 43.9
Anlaufstrom = starting current (A(Y) with the first winding, A(YY) second winding) = [A(Y)=97, A(YY)=158]
I am confused about what current should I consider in the sizing of the compressor starter parts (contactor, fuse, circuit breaker, thermal overload relay)?
Thanks in advance


texts: Interference between 27MHz RX and 5.8GHz TX

texts: I've got a 27MHz RC car and 5.8GHz Fat Shark video transmitter. When I drive the RC car using the video transmitter, it seems to lose signal from the 27MHz remote at a pretty close distance, say 2-3m through a wooden wall. When I turn the transmitting off and drive blindly in the same circumstances, everything seems OK. What can I do to improve the communication? Max range I'd hope for is 5-7m, and both components of my setup seem to work at this distance independently.


texts: Grounding a device with double insulation prohibited?

texts: There are Class I and Class II electrical devices. Class I devices need to have live parts grounded and Class II have double insulation. Why grounding of class II devices is prohibited? I mean, we can make double insulation and additional have connection to the ground.


texts: Detecting atmospheric voltages on high altitude balloon

texts:
Our High school is launching a high-altitude balloon payload and the experiment we want to perform is the detection of atmospheric voltages.

My friend and I were amazed when we saw this video where someone powered a small electrostatic motor with an antenna only about 100 feet in the air. With the Edge of Space Sciences mission we signed up for coming up, we thought it would be interesting to run some voltage experiments at a high elevation. The only problem we are running into is that we don't have a reference point (ground) because we can't dangle a long wire from 100,000 feet!

The idea we formulated was to measure the voltage between two small points (say 1 meter) with a microvolt meter and data logger and measure the change in voltage as the height increases. ex. 5 volts per meter at 1000 feet but 10 volts per meter at 10,000 feet elevation. This would give us an idea of how much voltage we would pick up if we were to elevate a giant wire by integrating the data.

So now we plan for either two metal plates or a dipole-like structure to measure the potential between to small points, and use operational amplifiers to capture the minute changes in voltages.

Well... According to this question I just asked about rectification, trying to measure the voltage or the "E Field" this method will not work, and we need a field mill. The problem with a field mill, however is the weight, and power consumption. We are limited to 800 Grams on this flight, and I don't know if a field mill will fulfill that requirement.

What is a good strategy to measure what we are trying to do? This PDF has some interesting measurements with electric field, I don't know how they did it, however.


texts: 3 bit synchrous up-counter stops at six but it need to be stop at seven

texts:
I am trying to design a 3-bit counter circuit with jk flip flops that count from 0 to 7 with a clock signal and remain constant at 7 until reset.
Counter counts well but it stops at six not seven.

My simulation using proteus :

Can you guys help me please.